Velleman HPS140i miniature DSO - a thing of beauty or ugly duckling ? - Page 1
Forum section: electronics / testgear

author: Fraser
author_rank: Super Contributor
timestamp: March 19, 2011, 07:55:31 pm
content: I have just visited my local Maplin Electronics store (UK) and spotted the new Velleman HPS140 Digital Sampling Oscilloscope that they stock. It is currently ‘on sale’ at GBP79.99, reduced from GBP129.99, until 22 March 2011.The maplin web site page is here:http://www.maplin.co.uk/velleman-hps140-handheld-pocket-scope-508678Needless to say, after a short 'play' I was adequately impressed and purchased one.The unit has a good web site dedicated to it so I shall not repeat the specs here.Web site is here :http://www.hps140.com/Take a look at the 'User Demo' videos whilst you are on the site.With a palm sized case and 40MS/S spec it appears adequate for the less demanding tasks that I have in mind for it. I would rate it in the same category as pocket multimeters... an unavoidable compromise but a very useful instrument to have around in the workshop or whilst mobile. Even Dave supports the ownership of the compact pocket multimeters. I wonder what he will think of this tiny DSO ? I don't consider it to be in the 'toy DSO' catagory. It obviously can't compete with my Rigol DSO or other full size scopes...... but have you ever tried squeezing one of them into a shirt pocketThe unit appears to be well made and has a resilient case and bright red rubber 'glove' to protect it from the knocks that life will inevitably throw at it. Inside the case there is a 800mA NiMH battery pack that uses AAA cells. These will be easy to replace when the time comes. There is very little to see when the case is opened. The PCB is easily lifted out of the case but all the electronics are hidden under a decent quality metal screening can. You can see this in the Velleman video on “battery fitting” at the above web site. I am not going to void the guarantee by opening the tin screening can just yet as I have only had the unit a dayThe HPS140 only has four buttons and the menu’s, though clear, take a bit of getting used to. The unit has several useful signal measuring functions including dBm and Watts into a range of impedances. The voltage reading is also True RMS which is nice to have. Volts peak to peak is also selectable.I already own several HPS10’s and these are useful provided you fully understand the limitations of the design and work within them. The HPS140 is no different but in terms of portability and bandwidth, it is streets ahead of the older HPS10 and most other miniature DSO’s. For the money, I have found Velleman portable and PC based oscilloscopes to be very good and reliable.If you fancy having such a portable little DSO at a pretty wallet friendly price you had better hurry as it's only on promotion at Maplin until 22 March 2011.Oh and I'd suggest buyers not be persuaded to purchase Maplins scope probe when buying the HPS140. You can get the same probes cheaper on e*ay. Search this forum for 'Wittig' and you will see that you can buy four decent Wittig X1/X10 scope probes for GBP18 ! = Plenty of sprares :-)MCS(UK) Probe Auction is here:http://cgi.ebay.co.uk/Set-4-200Mhz-wittig-W202-scope-probes-brand-new-/120691289053?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item1c19c2ebdd

author: saturation
author_rank: Super Contributor
timestamp: March 19, 2011, 10:42:25 pm
content: Can you take actual photos of your unit in action, and compare it against your other Velleman DSOs?I think beauty needs to take second spot to functionality, and safety. Velleman at least designs some safety into the scopes inputs, many of the low cost ones seem like they have none.Velleman does say explicitly it is designed for CAT II voltage use, although I don't think it has officially been listed by UL, TUV or any such safety agency for CAT II usage. Its uses a less clear bicolor LCD, say versus the color DSO Nano, but Velleman has better and more reliable specs, more in competition with a 6MHz Uni-T handheld scope. Velleman's reputation is a bit more established for low cost hand held DSOs, there are very few players in this field. Velleman's DSO have been around for ~ 10 years, and they seem just be reusing their scope modules and making tiny incremental improvements. After reading the user's manual and watching the videos, is pretty much my scope, except for some feature changes.I own an HPS40, its my 'sacrificial' scope and one I take around, the one I'll reach for first when testing an unknown fault with potential voltages that could fry my 1052e, after my DMM says its ok. I like the form factor of 140i better than the bigger HPS40. Th 140i lacks USB or old style serial port connections to ease getting screen dumps of waveforms. Nothing your cellphone or a digital camera can't handle though, particularly in macro mode ,to get details.The HPS40 uses 5 removable batteries, NiMH or alkaline, so its more flexible with power supply and charging. But 5 cells is a bit odd as replacement packs typically are often multiples of 2. Its easy to make a AAA NiMH pack, but its less convenient to replace as the 40.The 140i insulating sleeve could probably be both ergonomic and safety, the HPS40 plastic case is luckily not slippery but has no other layer of insulation.The 140i has a smaller screen, but it has tighter pixels. So it show the same data as the large HPS40 screen.If I brick my 40, I'll replace it with the 140i, its cheaper, and otherwise identical.See mikes electric stuff's test newer in the thread, he found sync issues above 1 MHz.FWIW, there is a chinese look alike, pictured left, of the Velleman HPS40, on the right. I didn't think these scopes were very popular, but I guess the design is successful enough for someone to spend effort to make a look-a-like.

author: Fraser
author_rank: Super Contributor
timestamp: March 19, 2011, 11:46:47 pm
content: Hi Saturation,When I get five minutes I will compare with my HPS10 and take some pictures. I also own the PCS100, PCS500 and UNI-T UT-81 so I will see how it compares with them as wellI understand that auto engineers like the Velleman HPS series for working in the difficult environs of the car engine bay or interior. Velleman made a dedicated car diagnostic kit using one of the HPS10's or 40's at one time.I concur regarding Velleman's experience and reputation in the field. They also provide excellent support if things go wrong and repairs are usually economically viable as they can be sent to the manufacturer in Belgium for repair. I have looked at the HPS140's rear label and it states IEC1010 600V CATII but no approval symbols are present. Th emax input before damage oon the BNC is stated as only 100V peak so care muct be taken to use the correct switch setting if using a X1/X10 probe to measure higher than this level.I was disappointed that Velleman didn't include a USB or serial link but I suppose it is built down to a cost and that was considered a luxury item that was not essential. I am pleased with the included measuring functions though. It is also worth noting that it has a standard BNC input and 1MOhm impedance, unlike some miniature scopes that have really odd connectors and scope probes that match an odd ball impedance that bears no resemblance to industry standards.Finaly, I should say my message title was a bit of a joke rather than me seriously considering whether the unit looked beautiful or not ..... beautiful engineering and ergonomics, now that is important to meMy Ugly duckling comment is really aimed at whether this unit is judged good or bad... just my odd sense of humour

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 20, 2011, 03:16:10 am
content: It looks like a very nice unit for working on the primary side of power supplies. 10MHz bandwidth should be enough for most transformer-coupled switching supplies. On the other hand, 40MHz sample rate is fairly easy to DIY. Also note that the probe is not included.

author: Unknown
author_rank: Unknown
timestamp: March 20, 2011, 04:01:00 am
content: Thanks for the pointer Aurora, spec wise it looks like a great unit. It certainly covers many of the applications of the Fluke 120 series at a fraction of the price. Not sure about safety though, I see this being used with mains a lot but I could not see any major components from the battery installation video.Elektor had done a review of scopemeters a while ago covering the older Velleman unit too.Time to take it apart?

author: Fraser
author_rank: Super Contributor
timestamp: March 20, 2011, 09:35:26 am
content: I personaly would not use the HSP140 on high energy or mains circuits. As I indicated, I see it more in the realm of the pocket multimeter and as such would use it on low energy circuits with voltages below 100V. The unit relies upon the probes attenuator to protect it from damage above 100V and that is a situation with which I am not that comfortable.Also note that on the label the unit warns users of the following:"BNC and DC input are not galvanic isolated"The BNC connector is also a metal shell type and not the safer plastic insulated type used on Flukes and even the Velleman PCS500. When a fully insulated probe is used (with plastic BNC shell), there is still an area of the BNC socket shell exposed with a potential shock hazard resulting.As I indicated. This unit appears great, if you use it within the constraints of it's design and specification.With regard to making a 40MHz DSO, I agree that this can be done but the neat case etc is always a challenge for me. In my world, time is money so it would not make economic sense for me to build a DSO such as this when it is available at a resonable price from a high street shopAs to taking it apart.... well I already did that and there is nothing to see, apart from a regulator and inductor, the electronics reside inside a closed metal shield, and until I know the unit is reliable, the metal shield stays in placeI will be asking Velleman to provide the HPS140 service manual as they made the HPS10 and 40 service manuals available via their support forum without fuss. Velleman tend to rely upon the copyright and hardware protection of their main processor chips rather than making a secret of the schematic diagram.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 20, 2011, 10:39:24 am
content: A 4-button UI on a scope sounds like a complete nightmare to me....£129 is too much for a toy scope - the cheapest Owon is 10x the scope for less than twice this price.at £79, it maybe worth it for fun though.

author: Fraser
author_rank: Super Contributor
timestamp: March 20, 2011, 11:00:28 am
content: I don't disagree that the 4 button UI is a challenge at first but the menu design is quite good so you soon get used to it. I feel it should be remembered that this DSO is designed to be ultra compact and not a bench scope killerAs I stated, it should be considered similar to the pocket multimeters in that it is easy to have in your tool bag or even shirt pocket. This would not be my choice as my one and only scope but as I am fortunate enough to have several analogue and digital scopes in different formats, this is just a product that fills a small gap in my inventoryI do think that Velleman could have had a few more buttons on the UI without over cluttering the front panel though. A scroll wheel or joystick, as found on many mobile phones, would have been another possibility. Cost may have been a factor.You are right to highlight that a very reasonable bench DSO can be purchased relatively cheaply these days. My Rigol DS1052E continues to impress me when I consider what I paid for it. For the hobbyist who is in the market for a general purpose DSO, I would not recommend any of the portable or PC based offerings. A decent bench DSO is an invaluable tool that does not have the compromises of the portable scopes or reliance on a PC. Before anyone mentions the top end portable scope offerings from the likes of Fluke, I own an elderly Fluke PM97 and find it very good, but the price tags tend to place them out of reach for the average hobbyist.Dave’s comments on a cheap analogue oscilloscope are also to be bourn in mind. They are so cheap on the used market these days that the hobbyist can get a decent bandwidth for a relatively small outlay of cash.The HPS140 has one significant key feature for me….. Portability, Portability, Portability

author: Zero999
author_rank: Super Contributor
timestamp: March 20, 2011, 11:02:16 am
content: Looks like good value for money.I agree it's probably not a good idea for mains usage but most uses for a 'scope are on ELV anyway. I think I'll get just for the RMS measurement as buying a DVM which will work up to 10MHz is pricey. I hope there's still some in my local store.

author: TheWelly888
author_rank: Frequent Contributor
timestamp: March 20, 2011, 11:44:32 am
content: Does the HPS140i DSO drain batteries in the same way as the HPS10 when switched off and how easy is it to access the battery compartment?Just out of curiousity as I own a HPS10 and my only beef with it is that I need to remove the batteries when I'm not using mine and one needs to use a screwdriver.

author: saturation
author_rank: Super Contributor
timestamp: March 20, 2011, 12:01:27 pm
content: Here's an example from an older eevblog post I made, of the HPS40 in action. I was troubleshooting a 300Vdc SMPS, and was surprised to see transients of 1000Vpp, but ~500V was above zero, that gives the net input exposure of 50Vdc after probe step down of 10:1. A Velleman screen dump. I wouldn't cry so much losing the Vellemanbut it took the exposure well, but I'd be hard-pressed to examine such circuits with 1052e or better scope.Those transients did not show up probing with a FLuke 87V, but it did suspect it, I could not stabilize the readout, and peak-hold gave unbelievable values, which turned out to be close to true.

author: saturation
author_rank: Super Contributor
timestamp: March 20, 2011, 12:04:32 pm
content: Hi Aurora,Reading on your electronic analysis in all these posts and your gear, you are therightperson to do the best revue of these scopes! You can make great comparisons, I'd like to see first is Velleman vs Uni-T 81, since Velleman DSO models are variations on their similar electronics.Many auto forums describe the HPS10 and it has a good following; its earned its reputation in the field, so regardless of its written specs its been proven practically. FWIW waveforms in autos are all under 100kHz, typically in the audio range. The competitive scopes for autos, with specs like a DSO Nano, are in the 5-15x the Velleman's costs, that's how it gained popularity. Auto dealership service centers are forced to buy name brand gear for liability purposes, while smaller shops and personal users can buy what they feel is useful. I have several old posts about these on eevblog.I agree fully with your safety concerns, using the scope probe as the first line of safety puts a lot on the probe, also the BNC jack is not insulated type. Luckily for low frequency with high voltage, like mains voltage, the probe is in spec, but one has be aware at high frequencies, voltage limits have to be derated.Quote from: Aurora on March 19, 2011, 11:46:47 pm

author: saturation
author_rank: Super Contributor
timestamp: March 20, 2011, 12:13:12 pm
content: You can check the quiescent drain current easily with an ammeter. I read those complaints too, so I checked. I use eneloop LSD NiMH batteries exclusively now, and now you can exclude the battery self discharge rate. I set of AA last me > 3 months.0.5mA when off, 160 mA ON, so it will run for about 12 hours on 2000mAH NIMH rechargable batteries, 4000 hours standby, that's ~ 5 months.Quote from: TheWelly888 on March 20, 2011, 11:44:32 am

author: Fraser
author_rank: Super Contributor
timestamp: March 20, 2011, 01:34:40 pm
content: Saturation,Regarding reviews.....I don't have a great deal of spare time these days but I would be happy to test and report on the behavior of my various scopes as time permits.Tell me what tests you would like and I will see what I can do over the coming weeks/months. I have a well equipped home RF lab with signal generators that are good to 1.2GHz but my Function generators and pulse generators are more humble. The fastest pulse generator that I own is an EH G710, rated at 50Mhz/ less than 5nS 10%-90% rise time.As I have said, I am very limited in the amount of time I have to ‘play’ so best endeavors will apply.

author: Fraser
author_rank: Super Contributor
timestamp: March 20, 2011, 01:57:09 pm
content: TheWelly888 ,Battery drain when off?Sorry, only bought it yesterday so not tested yet.The battery is easily accessed for replacement by the removal of the four case screws and the unplugging of the battery connector. The battery is a 3 AAA cell 800mA NiMh pack with a stated run time of 6 hours. No spec is given for self discharge times.

author: saturation
author_rank: Super Contributor
timestamp: March 20, 2011, 04:32:28 pm
content: Hello Aurora,Yes, I understand, time is short for everyone. At the least, just the highest frequency response of the Uni-T 81 versus your HPS140i. A square wave at 100kHZ for a the baseline, then 1MHz, which reflect on the 5th - 9th [at most], so the appearance will be an indication of its response to 5MHz - 9 MHz, the upper limit of their capability.If you still have time, using a fast pulse generator, determine the rise time of each.That's pretty much it. Ergonomics are not that essential.I saw an initial post will all your scopes! Impressive, I think you've edited it away. I think the Uni-T and the Velleman are the only true contenders in the low end DSO group. All the others, Fluke, Protek, Owon etc., are in a different class altogether.Quote from: Aurora on March 20, 2011, 01:34:40 pm

author: Fraser
author_rank: Super Contributor
timestamp: March 20, 2011, 05:02:49 pm
content: Hi Saturation,I will see what I can sort out this week for you. No problem with generating decent square waves at the specified frequencies and I can always try some analogue sine wave tests at the stated max freq to see what happens.Yes, you are right.... I removed the list as it didn't sit well with me when I read it back. I don't think people want to know how many scopes I haveIt looked like bragging to my eyes and that was not the intention

author: TheWelly888
author_rank: Frequent Contributor
timestamp: March 20, 2011, 07:36:00 pm
content: Quote from: saturation on March 20, 2011, 12:13:12 pmThanks for the data, saturation, but I use my HPS10 much less often than every 3 - 5 months! What I have done to get round the standby drain current is to put a small piece of plasticard ( eg from expired credit card ) between an end battery and the terminal when I'm not using it. It is also annoying that the HPS10 uses 5 x AA batteries when one gets them in packs of 2, 4 or 8!Anyway I like the HPS10 because you effectively have a floating input DSO when it's running off batteries only -I only wish I got the HPS40 for the LCD backlighting!

author: Fraser
author_rank: Super Contributor
timestamp: March 20, 2011, 08:03:01 pm
content: Thewelly888,Please be aware that the HPS140 comes fitted with a NiMh rechargeable battery as standard and so whilst this will save you buying batteries for it, you will not be able to quickly isolate the battery, and even if you did, the internal self dicharge rate of the Ni-Mh cells would mean they were pretty much discharged after a few months and would need recharging.The HPS140 also has the backlight supplied as standard. Why this was not the case with the HPS10 I will never understand. I fitted a backlit LCD panel to one of my HPS10's and it works well. The LCD is an industry standard product with 128x64 pixels and a KS0107 controller on board. Mine cost $20 delivered to the UK from China. It is a bit too thick to fit behind the front plastic but as a smashed front plastic and LCD was the reason for my replacement LCD purchase this didn't matter to me. You will likely wish to source a slightly thinner display unit. I attach the PDF datasheet for my backlit LCD for your info.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 21, 2011, 02:39:23 pm
content: My 'new toy' impulse got the better of me & I just picked one up. First impressions are quite good - screen update is very responsive and it's a nice size and feel, unlike the old Velleman unit I had a few years ago, which was just horrible.The 4-button UI seems to have had some thought put into it, but they could easily have added a couple more buttons.It will get taken apart tonight when I get home & that shield will be coming off...A few initial things -The charge lead is a USB DC/DC converter housed in a 'lumpy' USB plug, putting out 9V to a mini power jack. They should have put a USB mini or micro on there and an internal converter, to charge with a standard cable.It slightly defeats the point of having a very compact unit if you need to take an equivalent volume of leads etc with you. For a similar reason, it would have been nice to have a small probe included, with some neat way of it being stored in/on the case. Good that it uses a standard BNC though,There is a note in the manual saying "Do not operate the device when charging from USB", which is a bit doddy, presumably due to total power draw - if it was a problem it really should auto-disable rather than relying on a note in the manual that people won't read.The case feels quite nice - there's no tilt stand, but display contrast is wide enough that it's pretty useable flat on its back. It does need the rubber condom case though - the plastic is quite thin and does feel a bit flimsy when 'naked'.It would also have allowed for a USB data link which would have been nice if only to have the option of updating firmware (There is an internal ICSP header but I can't see them releasing updates that you need a programmer for...).It has a 'hard' on/off slide switch, so draw when off shouldn't be an issue, although as far as I can see it doesn't have auto powerdown.Another minor annoyance - it doesn't remember the probe x1/x10 setting after a powerdown.More later...

author: NiHaoMike
author_rank: Super Contributor
timestamp: March 21, 2011, 05:10:34 pm
content: QuoteThat's probably a ground loop or noise problem.

author: Zero999
author_rank: Super Contributor
timestamp: March 21, 2011, 05:30:57 pm
content: No it's because they can't guarantee the isolation/withstand voltage of the source used to charge the 'scope. Suppose you charge the 'scope from your laptop then decide to measure the mains with the 'scope? You could fry the laptop or be fried if you touch the laptop.For them to enable you to use the 'scope whilst it's being charged, they'd need to include an isolated DC-DC converter which would drive up the cost too much.

author: Fraser
author_rank: Super Contributor
timestamp: March 21, 2011, 05:49:21 pm
content: Some additional comments from me to balance my positive views of the product…..I must agree regarding the odd USB charger but I actually prefer to charge the unit from a regulated plugpack anyway so no great problem and I have regulated 9V car chargers as well.Regarding charging, my unit seemed to get a tad warm and smelled like hot electronics when charged off of the supplied USB charger. A check revealed that the USB charger outputs 9.91V (10% high). Velleman advised me that this was OK,"the electronics would just get a little hotter"On a 9V regulated plug pack it runs cooler and there is not the 'hot' electronics smell that was caused by the USB charger. Velleman failed to advise me of the acceptable charging voltage range.I believe the comment regarding using the scope whilst charging from a USB port MAY be due to the lack of galvanic isolation between BNC and charging port so a computer USB port could be exposed to damaging voltages. Current load on the USB upconverter is also a possible issue as Velleman state 500mA USB input current draw for an upconverted 9V 200mA capability.It is a pity that the charge LED remains lit whenever a charger is connected. The led does not extinguish when charging is completed. Charging the 800mAh battery takes 7 to 8 hours. The battery pack area of the case becomes warm after around 7 hours indicating that the cells have reached near full charge.I have to agree that the availability of a nice compact probe would have been great.I purchased a small digital camera case for my HPS140 and it fits like a glove. The probes and USB charger will have to go in a 'probe bag' like those that Fluke use. Another type of camera case may provide enough room for a standard probe to be stored.Velleman politely declined my request for the schematic or service manual, stating that the product was too new to market for the technical information to be released into the public domain. They did not say it would never be released, just not at the moment.My colleagues at work all agree that the HPS140 is a very neat and compact design providing better capability than any similar sized device presently on the market. A good compromise solution to the challenge of carrying an oscilloscope ‘just in case’ without it becoming a nuisance. A bit like the SLR verses the Compact digital camera really. The display is very clear with good, even backlighting but the four button keypad remains my only negative user experience really. I feel sure I will get used to it though.

author: Fraser
author_rank: Super Contributor
timestamp: March 21, 2011, 07:04:00 pm
content: I've just had my first use of the HPS140 in a real world situation......My neighbour came round with a CCTV Bullet camera and said he wasn't getting a picture on his CCTV.....would I check it out for him. I quickly plugged it into a 12V plugpack PSU and connected the HPS140 to it's BNC 'video out' connector.The result.... the BNC output went from a flat line 0V with camera power off, to +60mV DC offset with +-10mV noise with power on !It's safe to say the camera electronics received the 12V but the BNC tells the story.... it's stuffedThese cameras are basically disposable and not worth repair time. I have it for a post-mortem if I find the time.The whole test took less than the time taken to grab a 12V plugpack and connect the HPS140 to the Camera output. I know I could have plugged the camera into a CCTV monitor but then I wouldn't have seen the subtle dc level that came out of the BNC connector so it could have been a broken supply cable or dead input protection fuse.At least my neighbour knows it's dead and not another problem in his system. I checked his installation to make sure his PSU hadn't killed the camera. The HPS140 came into play again..... reading a DC voltage of 12.2V with only 1mV of ripple on it. Good enough for a camera. I fitted a new camera as a temporary measure and quickly set up the levels on it. Once again the HPS140 provided invaluable information regarding the CCIR signal. All was well in the end, with correct amplitude and sync pulse levels.It makes such a difference to have a fully functional oscilloscope literally in the palm of your hand

author: Fraser
author_rank: Super Contributor
timestamp: March 21, 2011, 07:11:38 pm
content: Almost forgot.....Whilst using the HPS140 you can hear reed relays operating inside it as it changes ranges. I had assumed that it would use some form of electronic switching or an instrumentation amplifier IC with gain control, fed from a fixed attenuator stage like many USB scopes. I must say I like the idea of a relay switched attenuator if that is what I am hearing.

author: TheWelly888
author_rank: Frequent Contributor
timestamp: March 21, 2011, 07:30:25 pm
content: Quote from: Aurora on March 20, 2011, 08:03:01 pmThanks for the datasheet for the backlit LCD, I might consider fitting a backlit LCD but I might consider getting a HPS140i instead!

author: Fraser
author_rank: Super Contributor
timestamp: March 21, 2011, 07:39:16 pm
content: A cheap and cheerful way to get light into an LCD display is 'side lighting' as found on old LCD watchesFor virtually no cost you could try adding some bright diffused LEDs to each side of the standard LCD panel and see if the lighting is adequate. Three each side should be enough. I have never done this on a large display but it is easily reversible and worth a try ?

author: Zero999
author_rank: Super Contributor
timestamp: March 21, 2011, 07:45:47 pm
content: Quote from: Aurora on March 21, 2011, 05:49:21 pmYes, that's what I meant. I would never dream they'd bother with isolating the input from the rest of the 'scope.

author: Fraser
author_rank: Super Contributor
timestamp: March 21, 2011, 08:09:45 pm
content: Hero999,I was typing my message whilst you were posting yours and they crossed in cyberspaceYou were first to state the reason

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 22, 2011, 12:28:07 am
content: OK folks teardown time :http://electricstuff.co.uk/velleman_hps140.htmlNo real surprises there. Pity about the crude battery management.(Ignore original comments re. time measurememt - hidden in additional menu..!)

author: saturation
author_rank: Super Contributor
timestamp: March 22, 2011, 12:14:09 pm
content: Great review, mike, shows how they managed to reduce costs as much as possible. The only thing left to see is its actual frequency response.The battery rests on the PCB with sponges; those sponges deteriorate in a few years but its easy to replace. Looks like it could rattle sometime in the future and bump against the casing. The HPS40 series have batteries cradled in their own plastic shell, firmly held down by the screw case, but enlarges the size much. Practically however, not sure how either design is better drop proofed, the 140 has the sleeve to absorb some shock while the HPS40 has a better more rigid case. The supplied carry bag gives it drop-shock proofing for transport though, and a container to stash the probes and an wall wart, if you have one.Quote from: mikeselectricstuff on March 22, 2011, 12:28:07 am

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 22, 2011, 01:42:50 pm
content: Quote from: saturation on March 22, 2011, 12:14:09 pmwill check this soonQuoteyes - they should have used high-density foam, although the case isn't really rigid enough to be able to apply too much clamping pressure, so this may be the reason for the thin foam. Some double-sided sticky pads would probably be better.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 22, 2011, 11:10:51 pm
content: A quick play with a signal generator reveals this unit has limited usefulness above 1MHz - abote this, trigger becomes jittery, and there are some aliasing issues. I have seen the auto-scale lock onto an alias, which can produce some rather bizarre trace displays!

author: Fraser
author_rank: Super Contributor
timestamp: March 22, 2011, 11:45:33 pm
content: Mike,Thanks for doing the teardown and test for us.Interesting findings. I presume you were presenting the unit with a square wave as if it's unhappy above 1MHz with a sine wave I would be really surprised. Thanks to your details of the ADC (ADC0801S040) we can see that the device was designed for video AD conversion and has an analogue bandwidth of around 10MHz with a Max sample rate of 40MHz. That may explain why it provides a decent enough image of 6MHz CCIR CCTV signals.Most of my work is in the analogue domain with occasional journeys into the world of 1's and 0's so this little scope should be fine for me. Not so sure about it being useful in the world of fast microprocessors though.I see your unit has the same capacitor mod as mine. I wasn't that impressed with the physical implementation of the mod but I suppose if it works OK it does the job well enough. It was nice to see the relay's present on the PCB. Like you, I find the absence of a managed charge circuit and any 'battery low' indication a disappointment. It doesn't cost very much to include such features these days.All in all, I am very pleased with my purchase and have already used it several times as it is just as convenient as grabbing my multimeter off the desk, and so quick to use. The very compact size makes all the difference for me in terms of convenience. The serious stuff will still happen in the lab with my bench scopes but the little HPS140 has now ousted my UNI-T UT81B from it's perch as the 'grab & go' scope

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 23, 2011, 12:08:35 am
content: Quote from: Aurora on March 22, 2011, 11:45:33 pmNope. Sinewave. trigger jitter is the first problem you see. Amplitude starts nosediving around 6MHz.QuoteActual usefullness is always the ultimate test, but I think omission of frequency/period/RPM measurement was a major missed opportunity.

author: saturation
author_rank: Super Contributor
timestamp: March 23, 2011, 09:46:58 am
content: Ouch. Sorry to hear, I was looking forward to this as potential replacement for my HPS40 should it get bricked. Test waveform is sine wave > 1 MHz and up? I'll post HPS40 screen grabs.Aurora, Mike's quick test is another good reason to compare frequency response to the Uni-T 81.Quote from: mikeselectricstuff on March 23, 2011, 12:08:35 am

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 23, 2011, 10:50:29 am
content: Here's a vid showing response from 1-10MHz.

author: saturation
author_rank: Super Contributor
timestamp: March 23, 2011, 11:15:14 am
content: G'morning mike from NE USA. You beat me to it! You are fast. That response is much like the HPS40, its not too bad.I agree fully to 1 MHz, its at its best. Between 1-4MHz, is 'ok', and above 4 MHz, you need to read between the lines. If I saw anything above 10 MHz, I better open the windows and make sure my glue containers are shut tight. Given its 40 MHz clock and sampling rate, I limit its use to 4MHz and below.Since the PIC MCU uses its internal oscillator, I think jitter is heavily part of the low internal clock stability, but above 4 MHz or so, the sampling rate increasingly plays havoc on waveform stability since its can't trigger at the right levels consistently. Square waves are stable at 1~3 MHz, to suggest its able to lock in a bit better on step responses than sine.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 23, 2011, 11:49:17 am
content: Quote from: saturation on March 23, 2011, 11:15:14 amI don't think so, as if it was clock jitter you'd see waveshape distortion - the magnitude of the trigger jitter is way more than any visible distortion of the waveform - when frozen the waveform looks pretty uniform.Assuming the triggering is done via a seperate path to the ADC signal processing, it's more likely some variable-latency issues and/or limited performance of the trigger hardware, which I assume is that LMV934.

author: Fraser
author_rank: Super Contributor
timestamp: March 23, 2011, 05:35:49 pm
content: Mike,Regarding frequency and period measurement... did you mean dynamic or static measurement ? The HPS140 does offer frequency and period measurment of a static signal in the 'Hold' condition by use of the markers.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 23, 2011, 05:38:18 pm
content: Quote from: Aurora on March 23, 2011, 05:35:49 pmYes, but it would be so much nicer, and entirely feasible, to have it do automatic freq, period, pulsewidth, duty cycle, RPM measurments as well for no extra hardware cost, which would make it so much more useful.

author: Fraser
author_rank: Super Contributor
timestamp: March 23, 2011, 05:56:09 pm
content: AgreedI have just run my HPS140 through the same test as you and can confirm mine bahaves in exactly the same manner. If I am totally honest I am disappointed with the triggering performanceLots of jitter above 1MHz. Using 'Hold' provides a clearer image but I expected the waveform distortion due to aliasing errors to cut in before triggering started to let go.If I were writing a report on the HPS140, I would say 'could do better'.I will have a quick look at how my UT-81B behaves and report back.UPDATE:A quick test of the UT-81 wiped the floor with the HPS-140..... ho humI have an acceptable trigger stability on a sine wave being displayed at 12.8 MHz (yes 12.8MHz). There is some jitter but nowhere near as bad as on the HPS-140 at 2MHz ! The UT-81 is suffering attenuation at 12.8MHz of course but the display is stable enough for assessment.I guess this either makes the UT-81B a good performer or the HPS140 a FAILMore when I have time.

author: Fraser
author_rank: Super Contributor
timestamp: March 23, 2011, 07:14:35 pm
content: I'm starting to think the HPS-140 has a design fault as the triggering is so unstable above 1MHz whereas the UT-81B is far more stable.I have just completed some tests and pictures will follow. It is safe to say that the UT-81B is a far superior product in terms of it's trigger lock and bandwidth. I'm guttedI can tolerate compromise but this may be a step too far. An email to Velleman may be in order to ascertain how well they expect the unit to perform.

author: Fraser
author_rank: Super Contributor
timestamp: March 23, 2011, 08:32:18 pm
content: Ok I quickly did a comparison between the HPS-140 and the UT-81B.The test setup used a Grundig/Digimess FG100 20Mhz Function Generator (this uses a MAX038 core). The function generator was working into a 50 Ohm through termination then split using a common BNC T piece feeding the two oscilloscopes via 25cm RG58U patch cables. Both oscilloscopes should see the same signal but it is acknowledged that the T splitter is less than ideal in terms of impedances etc.I presented the oscilloscopes with a square wave and photographed the displays at various frequencies. The results are shown in the pdf attachment. The 10MHz and 15 MHz signals were Sine waves and I was just interested to see how the UT-81B coped with the higher frequency signals.With regard to jitter.... both oscilloscopes displayed very minor jitter at the lowest frequencies due to minor sampling point tolerances, The UT-81B maintained a stable and well triggered waveform display up to beyond 13MHz with jitter becoming an issue at 15MHz. The HPS-140 displayed minor waveform jitter at 1MHz and was becoming unstable at 2MHz, increasing to unacceptable jitter at 4 Mhz. HPS-140 triggering was lost at 5MHz.Rise time measurement at 1MHz was not possible due to the limitation of the timebases (100nS/Div on UT-81B and 25nS/Div on HPS-140)It would be fair to say that the HPS-140 is a compromise (compromised?) solution to achieve small size. It is for potential purchasers to decide if it is compromised to the extent that it loses credibility as a 40 MS/s 4MHz BW DSO. I shall be using mine for quick checks to ascertain the presence and level of various sub 4MHz signals. I am still disappointed at the trigger performance however, and shall be raising this with Velleman.

author: saturation
author_rank: Super Contributor
timestamp: March 23, 2011, 08:49:59 pm
content: Wowza. Thanks so much for doing these Aurora, Mike, and the commentaries too. I keep thinking of the 140 as the same as 40 but there are differences, AFAIK. Will duplicate your tests as you did and post my results. Comments later.

author: Fraser
author_rank: Super Contributor
timestamp: March 23, 2011, 11:22:57 pm
content: The HPS-40 is a somewhat more complex circuit than the HPS-140 so I would expect better performance in terms of triggering.I attach the schematic/Service manual for those interested.

author: saturation
author_rank: Super Contributor
timestamp: March 24, 2011, 06:13:27 pm
content: thanks Aurora for the calibration and maintenance manual; its one reason I got the Velleman is that I have access to repair data. The 40 is 5Ms/s, not what is described in some of their literature and oversamples x8 for repetitive sampling.I don't have the trigger problems you both describe well in this thread. I'll post static photos later today of distorted waveforms at > 8 MHz, but synced and stably displayed.Quote from: Aurora on March 23, 2011, 11:22:57 pm

author: Zero999
author_rank: Super Contributor
timestamp: March 24, 2011, 10:23:20 pm
content: I received mine yesterday. I've still not got round to testing it. Oh well, it might not be up to the specs but I don't regret buying it, even if it's limited to only 2MHz. As far as I'm aware there are no hand held 'scopes which can work up to 2MHz on the market for that price and even a true RMS meter with that frequency range is expensive. It's still fine for audio and low speed PIC stuff. I'd only be pissed off if something better is available for the same price.

author: Fraser
author_rank: Super Contributor
timestamp: March 24, 2011, 11:29:35 pm
content: One thing that I have noticed about the jittery trigger. On my unit the jitter appears to be a sampling point variation on the waveform so I can press the hold button and the display shows a clean waveform, at leat up to 4MHz. I will have to do some more testing but life turned hectic real quick today so no time to 'play'.I have decided that the unit is worth the money to me as it provides the portability I need, with adequate performance for the low feq work that I regularly do. I am often looking for noise on audio and power supply rails.I will still contact Velleman via their forum as soon as I get a chance (www.velleman.be) and I suggest others do as well. Velleman have been helpful to me in the past and they may respond to our concerns regarding the trigger stability.UPDATE:I have raised the HPS-140 issues with Velleman on their support Forum. I await their response. I recommend others state their concerns on the same Forum topic if you wish to see the issues addressed.Forum message is here:http://forum.velleman.eu/viewtopic.php?f=9&t=5913

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 25, 2011, 12:41:59 am
content: Looks like it may be more of a software issue - did some probing around and found a couple of signals from the front-end to the PIC, and neither of these show any jitter :BTW I also figured out why they reccommend not charging from USB while using - the power ground is NOT connected to signal ground.The signal ground sits at about 2V above supply ground, presumably to simplify handling of negative inputs. Fortunately there is no smoke if the power and signal grounds are shorted, the trace just disappears.

author: Fraser
author_rank: Super Contributor
timestamp: March 25, 2011, 12:05:00 pm
content: Thanks for the excellent videos Mike and for posting the links on the Velleman forum.The response from Velleman (reproduced below) is at least open to the idea that they may have a problem and will investigate it.From Velleman:"We appreciate your feedback.Possible problem has not been reported yet.We are currently looking into this issue and we will post an update a soon as we have more info."

author: Fraser
author_rank: Super Contributor
timestamp: March 25, 2011, 01:28:25 pm
content: GOOD NEWSVelleman support is as good as ever and have just posted the following on their forum:====================================Velleman response:"We have managed to simulate the problem and source the cause of troubles.It appears to be related to the firmware, not the hardware.Unfortunately, for copyright reasons, we cannot supply .hex code.We can offer a free firmware update if you return the scope to our tech. dept.Velleman Instruments Tech. Dept.Legen Heirweg 339890 GavereBelgiumPlease include a copy of this conversation.As a courtesy, while your scope is here, we can offer a free custom splash screen for your scope.If you send an 128x64 bitmap (2 colour) to support (at) velleman (dot) be then we will include it in your scope.Once again, thank you for your feedback and sorry for any inconvenience."=======================================Now that's what I call fast and correct response to a situationMany thanks to Mike for highlighting this problem and generating the excellent videos for us.

author: saturation
author_rank: Super Contributor
timestamp: March 25, 2011, 05:05:11 pm
content: Great, if its purely firmware, both Mike and your good work brought to light something they weren't aware off. If you get the firmware upgraded, it would be good to retest its performance again.

author: FreeThinker
author_rank: Frequent Contributor
timestamp: March 25, 2011, 06:02:00 pm
content: Just a thought but was it excellent customer service or 'Dave Power'? Seems that a lot of manufacturers keep an eye on the EEVBLOG and this can generate fast responses

author: Fraser
author_rank: Super Contributor
timestamp: March 25, 2011, 07:23:37 pm
content: From past positive support experience I have had with Velleman, I would like to think that they continue to offer very good customer support.I would however say that no decent manufacturer wishes to have negative comments about their 'new baby' splashed across the internetIn this case I am just very pleased that my HPS-140 will recieve a 'fix'.I will test it again after it returns but will leave Mike to do any video's hr thinks appropriate as he has a knack for it and I don'tI hope Velleman are genuinely pleased that I reported the issue to them but I must admit that I am very surprised at the support route these days. I used to contact them by direct and private email but they now like to receive questions via the support forum. I don't like complaining to a good company in public as that's a bit like washing their dirty laundry in public and can be considered a tad aggressive at the earliest stages of a complaint. Velleman gave me no choice in this case so I went into print to show my dissappointment. It has aired the issue though, so other customers may benefit which is good.I have no axe to grind with Velleman and honestly believe them to be a decent European company.

author: Zero999
author_rank: Super Contributor
timestamp: March 25, 2011, 09:42:02 pm
content: Looks good but that means I've got to post the meter off to Belgium, hoping it gets there in one piece. I'll have to look into recorded delivery.Oh well, at least the money I've saved though buying it earlier should more than make up the shipping costs which I doubt Vellemen will reimburse me for.

author: Fraser
author_rank: Super Contributor
timestamp: March 25, 2011, 10:53:49 pm
content: Agreed.Last time I reported an issue with their PCG10/K8016, they sent me a new PAL chip and offered me two of their kits FOC as compensation and thanks for my help in identifying an issue. BUT that was when I was dealing with a service manager and not discussing the matter via a support forum.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 25, 2011, 11:35:42 pm
content: Quote from: Aurora on March 25, 2011, 07:23:37 pmA public forum thread showing how efficiently they dealt with it is good for them in the long term. Most things don't go wrong most of the time. It's the attitude of a company when things do that seperates the good from the bad.Now what to put in that custom graphic....

author: Zero999
author_rank: Super Contributor
timestamp: March 26, 2011, 06:25:28 pm
content: I've just realised what you mean about the poor battery management. It doesn't even have a low battery warning. I was using it today to measure the output from my signal generator when the display went dim, then it started rebooting repeatedly like a Windows PC with a virus.I suppose it's good they're fixing the triggering problem so quickly, not many companies would do that. I think I'll wait a week or so before sending mine of, in the hope others find more bugs which can be fixed. I'll be mentioning the poor battery management to them, in the hope they fix that too but I'm not going to hold my breath. I'll also bring the cost of shipping to their attention but wouldn't expect the money back, just an apology and some gift vouchers would be nice.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 29, 2011, 01:08:10 pm
content: Just noticed that the thread has been deleted from the Velleman forum.

author: Zero999
author_rank: Super Contributor
timestamp: March 29, 2011, 05:18:15 pm
content: Quote from: mikeselectricstuff on March 29, 2011, 01:08:10 pmSounds ominous.There again, perhaps they've rectified the problem and recalled all existing units from the retailers? If so they should've just closed the thread.

author: Fraser
author_rank: Super Contributor
timestamp: March 29, 2011, 05:42:18 pm
content: I noticed the thread deletion today as well. I needed the text to send with my unit. As it happened I had the relevant text posted in this thread so just cut & pasted it into my letter.I mentioned 'airing dirty laundry in public', well I suspect Velleman are thinking the same. They have received our complaint, responded well, and probably contacted their distribution network to put sales on hold (?). As to what happens to people who have already purchased the unit, well I suppose if they don't complain they will never know that this issue has been identified.Velleman may have had concerns regarding my somewhat direct writing in the original message. They would not wish sales of the HPS-140 to suffer as a result and the firmware issue. The whole matter will likely be old news soon and I suppose it could cause confusion ?I was surprised to see it deleted though. Better to have issued a formal statement detailing effected firmware versions, and then locked the thread.For info: The cost to return my unit by Royal Mail International 'Signed For' with £100 cover was GBP10.34 which is unwelcome but we will see what Velleman offers me by way of compensation.UPDATE:Maplin Electronics(UK) are now showing "Preorder" against the HPS140 on their web site and they had plenty of stock a few days ago.I suspect they are awaiting new stock with the fixed firmware.

author: Zero999
author_rank: Super Contributor
timestamp: March 29, 2011, 06:00:27 pm
content: Do you think it's worth contacting Maplin about the problem?Is it possible they might exchange it for one with fixed firmware? I'd rather pop in to my local store than put it in the post.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 29, 2011, 06:07:28 pm
content: QuoteOr are hiding it to prevent more people requesting upgrades.My local store only had one in stock so maybe they just sold out after the publicity here..!For a new product like this they probably did a small initial batch to fluch out any problems anyway.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: March 29, 2011, 06:08:43 pm
content: Quote from: Hero999 on March 29, 2011, 06:00:27 pmSeems unlikely anyone at Maplin would even know what firmware is...

author: Fraser
author_rank: Super Contributor
timestamp: April 05, 2011, 04:26:38 pm
content: My HPS-140 has just returned from BelgiumAll looks to be in order with no scratches or damage to my nice new 'toy'The firmware version now shows version 1112 on boot.A bit of a busy evening ahead but will endeavor to test the trigger performance and repot findings ASAP.P.S. I asked for a scope probe by way of compensation for the hassle and postage cost, I received one in the returned package so I now have an HPS-140i as opposed to the HPS-140.... thanks Velleman

author: Unknown
author_rank: Unknown
timestamp: April 05, 2011, 04:30:35 pm
content: Quote from: mikeselectricstuff on March 29, 2011, 06:08:43 pmCustomers might. lolOpportunistic Aurora...let us know if it has been fixed.

author: Fraser
author_rank: Super Contributor
timestamp: April 05, 2011, 05:30:05 pm
content: OK, I've run a real quick and dirty test using my 20MHz function generator.Velleman have significantly improved the triggering but it isn't perfect. Read on.....With a Sine wave input the HPS140 triggers fine up to 6.3MHz but you are getting signal shape distortion by that point due to aliasing.When a Square wave is input, the trigger remains locked until 7.6Mhz but above that frequency you get garbage displayed and not a waveform.One remaining weakness is the 250nS timebase limit. 100nS would be more helpful as signals start to get cramped as you approach 4 MHz.When I said it was improved but not perfect, I should state that for my use it is perfectly acceptable. The waveform does have slight jitter remaining due possibly to slight trigger point variation or trigger processing tolerances. It is interesting to note that the UT-81 also has similar amounts of jitter and the HPS-140 seems no worse. The HPS-140 now provides an adequately stable waveform at 4MHz which is what I expect of a 40MS/s DSO.The improvement in the waveform display performance on the Velleman HPS-140 is significant and satisfies me so I am a happy customer.It is also pleasing that Velleman gifted me the 60MHz oscilloscope probe as they were under no obligation to do so. This tends to support my view that Velleman respect their customer base. Interestingly, there was no report provided with the returned unit, just a shipping note.When comparing the HPS-140 against the UT-81B, I have to admit the UT-81B is a superior product considering the similar cost when I purchased it (GBP90) The UT-81 has the benefit of a larger and clearer display offering better resolution and detail especially when looking at complex signals like a CCIR TV picture waveform. I want the HPS-140 for maximum portability. Where tiny size is not so important but a portable handheld DSO is required, the UT-81B would be my recommendation.

author: Zero999
author_rank: Super Contributor
timestamp: April 06, 2011, 04:41:40 pm
content: Good, I think I'll send it off then.

author: Fraser
author_rank: Super Contributor
timestamp: April 06, 2011, 06:16:16 pm
content: I sent mine Royal Mail international 'signed-for' plus £100 insurance and it cost around £10.This is why I asked for a free HPS-140 scope probe. and I suspect why they sent me one. It would be worth you asking as well.Note: I used a well padded box that originally contained a new HDD and this ensured safe transit for the DSO. Velleman used the same box to return my unit. It would be sensible to take similar precautions to avoid transit damage. (Padded envelopes get chucked around)

author: gazzzman
author_rank: Newbie
timestamp: April 07, 2011, 02:18:57 pm
content: hi there folks!I have just bought the HPS140 from CPC to suplement my old (valve) scope!as it is a little lighter!before I have even charged it, I came looking for info LOL!now my question.. my firmware version says 1041 and that "sounds" a lot older than the 1111 I saw mentioned above!am I being paranoid?funny really, been in electronics 30+ years and on the internet since 97 and this is the first time I have ran across this forum!so cyberspace really IS that big LOL!

author: Fraser
author_rank: Super Contributor
timestamp: April 07, 2011, 05:14:14 pm
content: Hi gazzzman,Your firmware is older but that does not mean it has the problem described in this thread. I can't remember what firmware was fitted in mine before I sent it off to be upgradedIf your unit has a stable trigger at above 1 MHz you are OK. If not, it will need to go to Velleman for an upgrade of firmware.One of the other members should be able to tell you the firmware revision that has the bug in it as they may not have sent their DSO off for upgrade yet.Newer firmware may have other bug fixes as well so it might still be worth getting it upgraded to the latest revision.A thought... not all firmware version numbers are sequential numeric updates. I have a suspicion that Velleman use a YYWW format. i.e 1112 could mean the version produced in the 12th week of 2011. No proof but 1041 would be the version produce in the 41st week of 2010 which fits the release date pretty well.Fraser

author: gazzzman
author_rank: Newbie
timestamp: April 08, 2011, 08:39:04 am
content: hi Aurora!thanks for the replyI will go and find someone with a reasonable function generator, and see how the scope performs!1111 would seem also to sit right with the datecode / version theory, so we will wait and seeit is a real shame that Velleman didn't fit a USB port at least for firmware updatesthere are always some bugs in release software and a provision for rectifying these bugs without sending the scope back to Belgium would have been a sane decisionthanks for your help!I will report back after I have done a few tests!

author: jaytourist
author_rank: Newbie
timestamp: April 08, 2011, 10:05:48 am
content: dude, have you tried to recharge the battery? you can try that too just to make sure it has no problem.

author: gazzzman
author_rank: Newbie
timestamp: April 08, 2011, 12:15:39 pm
content: hi there jaytourist!yes, it's charged and appears to be working fineI just don't have a reliable signal source to hand right now to assess the performance!most of my better test gear is ancient!my other scope for example is a Gould 50Mhz Dual beam Valve job (circa 1970) uses a pair of 807's in each of the deflection output stages! it is a monster!but, yes. it still does the job! despite it's 65Kg!but my Advance function generator (waveform generator actually) uses B9A valves and only goes up to 1 MHz LOL!as I rarely bother with electronics that contain those nasty little three legged fuses (at a personal level) I rarely need any better test gearwork (sadly) is another matter and I sadly lament the loss of analog video and CRT's!dealing as I do with LCD, DLP and Plasmaas far as work goes, economics dictate I am little more than a board jockey these days

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: May 11, 2011, 10:49:02 pm
content: Finally got my HPS140 back after about a month. Firmware version shows as build 1112Trigger issue appears to be resolved, but still not really useable over 5MHz.

author: Fraser
author_rank: Super Contributor
timestamp: May 11, 2011, 11:12:35 pm
content: Mike,Totally agree.What I find interesting is that the UNI-T UT81B manages to display a decent sine wave at 15MHz with a 40MS/s sampling rate yet the little HPS-140 sort of gives up trying at around 7 MHz and hits a 'brick wall' , producing total rubbish on the screen. I am assuming that this is due to a much simpler design and signal processing algorithm in the smaller unit that cannot adequately cope with the aliasing that occurs above 7 MHz. There is also the possibility that the ADC tops out at 7MHz as it is designed for video signal conversion and such signals are usually around 7MHz in bandwidth. The ADC chip datasheet claims 10MHz capability though.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: May 11, 2011, 11:30:05 pm
content: You need a good filter in front of the ADC to avoid aliasing while preserving bandwidth, i.e. a fairly sharp cutoff - the HPS140 is obviously built to a minimum cost, and has simple filtering.At the 5-10MHz range you will probably only get the extreme aliasing artefacts at frequencies that are close to exact fractions of the sample rate. Do you feel lucky...?I note the box says "bandwidthup to10MHz"..

author: AheadOfTheTimes
author_rank: Contributor
timestamp: November 09, 2011, 09:52:05 pm
content: Here's a question on the new Velleman: how is it regarding emitting unwanted RFI? The fact that the triggering is problematic suggests it might be noisy. In fact I tried an expensive Fluke ScopeMeter and even running from the internal battery the emissions were blatantly bad. An AM radio would buzz from it at a distance of about 4 feet! I've heard the other Velleman's are better in this regard. Anyone have an AM radio or other way to test?

author: ivan747
author_rank: Super Contributor
timestamp: November 10, 2011, 12:13:38 am
content: Quote from: AheadOfTheTimes on November 09, 2011, 09:52:05 pmI have both an AM radio and a HPS-10 scope. Tell me what you want me to do, specifically and I'll try to do the tests.

author: saturation
author_rank: Super Contributor
timestamp: November 10, 2011, 10:58:16 am
content: Hmm that's pretty awful, I don't get this with the HPS40, but its an older model and claims FCC certification [ to be free from interference]. If you could post a video about it, and let them know, they responded to posters here with a bug report, as you can read on the thread.Quote from: AheadOfTheTimes on November 09, 2011, 09:52:05 pm

author: AheadOfTheTimes
author_rank: Contributor
timestamp: November 10, 2011, 11:11:36 pm
content: Thanks Ivan.Most AM radios (unless they have noise suppression circuitry) will buzz if tuned between stationsand held near a broadband noise source (you probably know the AM antenna is generally a small ferrite bar inside the unit).Just tuning to the low end of the dial is usually enough. Try holding near a computer to see if it works.Then see how far from the Velleman the radio will buzz. Could be inches or a few feet. If the radio buzzeseverywhere in the room with everything you own off, call the power company and get them to checkthe overhead lines.Quote from: ivan747 on March 09, 1974, 07:13:21 pm

author: ivan747
author_rank: Super Contributor
timestamp: November 11, 2011, 02:22:40 am
content: Quote from: AheadOfTheTimes on November 10, 2011, 11:11:36 pmI will perform the test tomorrow or this Saturday. It is 10:30 and I'm going to bed.

author: ivan747
author_rank: Super Contributor
timestamp: November 11, 2011, 11:34:34 pm
content: Quote from: AheadOfTheTimes on November 10, 2011, 11:11:36 pmThe oscilloscope makes the radio buzz when it is held about 10cm away from it. It is a high pitched noise, probably produced by the digital side of the scope, which is the middle part where the buttons are. The HPS-10 uses a very nice three board construction, one board is the screen, the other is the button interface board and the last one contains the analog and digital circuitry, well separated. The screen is above the analog area of the main board; the buttons are above the digital area of the main board. The lower part of the scope is occupied by the battery compartment. I have some pictures of the scope I took a while ago, if you want them, but I would probably make another thread for that.

author: Fraser
author_rank: Super Contributor
timestamp: November 13, 2011, 05:13:11 pm
content: RFI at 10cm is actually a pretty good result ! Running digital electronics near a very sensitive MF receiver using the ferrite aerial, in the H field domain is a pretty tough test, as metal RF shielding is less effective against H field emissions. I do EMC/TEMPEST work and use EMC E field & H field probes to test emissions from equipment. I would expect a reputable company like Velleman to do similar before placing the infamous CE sticker on it. My HPS140 is well behaved with regard to RFI generation and I see nothing to suggest that it is any worse than any other digital electronics. Much RFI emits from the LCD panel areas of equipment as they are usually poorly screened or unscreened.

author: AheadOfTheTimes
author_rank: Contributor
timestamp: November 15, 2011, 08:35:45 pm
content: I agree 10cm is not bad. If anyone can compare to an older handheld Velleman I'd appreciat it. My Agilent DMM (1252A) is quiet until a couple inches from the display (except when measuring capacitance, when it radiates from the leads). My Tek handheld scope radiates from the outer conductors of the coax probes (with no signal).

author: ivan747
author_rank: Super Contributor
timestamp: November 16, 2011, 10:57:05 pm
content: Quote from: AheadOfTheTimes on November 15, 2011, 08:35:45 pmIsn't the HPS10 the oldest model? I have the HPS10, not the HPS140i, just in case you though I have the '140.

author: AheadOfTheTimes
author_rank: Contributor
timestamp: November 28, 2011, 03:20:37 am
content: Oh, I had heard previously the HPS10 was good in this regard, so you've confirmed that... would love to know about the 140 or other models. Can anyone report?

author: Fraser
author_rank: Super Contributor
timestamp: February 15, 2012, 04:34:28 pm
content: Resurrecting an old thread here but it may be useful to others as Velleman are playing hard ball on the firmware upgrade.I bought another HPS140 recently and upon switching it on it announced firmware 1041 rather than the later 'fixed' version 1112.Before buying an HPS140, I advise the potential buyer to confirm which firmware is loaded.I note that Velleman are not accepting this as a firmware bug on their forum, which was a great surprise to me. Further, Velleman are now stating that the 1112 firmware will be installed at the customers request for free but with ALL postage and handling charged to the customerOh dear, this is not the Velleman support that I have known and loved over the years. Its bad enough to have a bug in your firmware on new equipment, but to then be told you have to pay postage to and from the factory is verging on rude and very poor support practice when an identified F/W bug is involved. It is a great pity that the HPS140 cannot be firmware flashed by the owner.I have written to Velleman asking for a firmware upgrade at no cost to me. We will see how they respond on this occasion. I am hopeful that Velleman will take the honourable path and not charge postage and handling. If you recall, last time I sent an HPS140i to them, they were so concerned about the inconvenience and my postage costs that they repaid me in kind in the form of a free oscilloscope probe. I wonder if that good customer service is still alive and well ?Aurora

author: Fraser
author_rank: Super Contributor
timestamp: February 16, 2012, 09:26:41 am
content: A fast response from Velleman."You can still return your unit for a free firmware update (shipping not incl).Please return it to:Velleman Projects Tech. Dept.Legen Heirweg 339890 GavereBelgiumMake sure to include a note that says 'firmware update', so that our engineers know what to do. "So it would appear that Velleman are yet another company that has lowered its support standards. I shall approach them again on this matter as its not really good enough. I have to say that their stance that the triggering problem isn't actually a 'Bug' in the firmware is laughable....'you can still use the DSO for low frequency work' is their opinion of the firmware situationAurora

author: saturation
author_rank: Super Contributor
timestamp: February 16, 2012, 02:19:14 pm
content: Sorry to hear. Maybe better to return the unit from where you purchased it from, since they have older stock. Buy elsewhere then ask the seller if they can check the firmware version?

author: Fraser
author_rank: Super Contributor
timestamp: February 17, 2012, 03:27:57 pm
content: Good newsVellerman made an error in their reply to me. They will cover the firmware update under warranty and without the return postage cost.All is well again in my little worldAurora

author: Unknown
author_rank: Unknown
timestamp: February 17, 2012, 09:01:17 pm
content: Sure, an error. We accidentally gave you the impression that we don't care about customers. It just means you can force them to do what a good company would have done in the first place if you're persistent enough. People with less experience would probably have given up and paid for shipping themselves.

author: teaker1s
author_rank: Newbie
timestamp: April 23, 2012, 12:17:47 am
content: Hi has this been resolved or is the UNI-T UT81 still a better bet at a similar price?

author: teaker1s
author_rank: Newbie
timestamp: April 23, 2012, 12:38:25 am
content: Verification deletes my message but at £89 is this a bargain or is it worth another say £50 for something else? mine is due tomorrow.

author: Fraser
author_rank: Super Contributor
timestamp: April 23, 2012, 05:03:00 pm
content: A Bargain..... Hmmm ... you do get what you pay for with DSO's and there are some very nice bench DSO's available for very reasonable money these days, new or used. I picked up a lovely Tektronix TDS220 recently for £130, it is worlds apart from the Vellerman products. You have to consider your specific needs. I needed some highly portable oscilloscopes for use when out and about, but as I have stated before...you pay a premium for the portability. I would always recommend a bench oscilloscope over a portable model if bangs per buck is a factor. I just bought a lovely analogue Hameg HM1004-3 scope for GBP120. Its a nice bit of kit with a true 100MHz bandwidth. You just have to consider your true needs carefully before spending your hard earned cash. I like all of my oscilloscopes, but for differing reasons. Do not discount buying used equipment from a reputable seller.Aurora

author: saturation
author_rank: Super Contributor
timestamp: April 23, 2012, 06:08:38 pm
content: The Velleman's are decent scopes for the money, but the Uni-T 81D is a better general purpose portable scope as it give more bandwidth for your $$. However, that said, if you have a specific need, why spend more?A principle reason to have these types of scopes is to insure the inputs are truly floating, most all desktop scopes use earth ground, the only way to remove it is to float the scope, which is hazardous, or use special probes.For example, if you probe the inputs of a benchsupply with a standard DSO, you will very likely get a huge bunch of noise, and good sized ripple if not more artifacts; this is partly because the scope's earth ground and the probes form an aerial and pick up RF, and if you have the common ground on a bench supply, add to it ground loops. With a truly floating scope, this is far less a concern.Quote from: teaker1s on April 23, 2012, 12:38:25 am

author: popultek
author_rank: Newbie
timestamp: September 01, 2012, 05:49:56 am
content: How great a Handheld Oscilloscope. Is made in China?

author: saturation
author_rank: Super Contributor
timestamp: September 01, 2012, 02:31:38 pm
content: IIRC, Taiwan. While well made it has its faults as this thread describes but its good enough for low frequency and low power work.

author: grepas
author_rank: Newbie
timestamp: October 21, 2013, 07:22:44 am
content: A thread-bump, but because this has a high Google rank for people searching on info for this machine I am going to use it to note out a couple of drawbacks, and please correct me if I am wrong about them:"You get what you pay for" sure is appliciable in this case, nevertheless, this machine is very usable for some field work but:-It comes with no real manual (the "manual" is just a short guide). You essentially have to figure it out yourself. There is no real official manual on the Web either.-No trigger indicator (which is important in single-shot mode). Haven't seen this on any other scope.-Autoranging works, to be honest, so-so. It is very easy for the scope to go into "bananas" mode where it cannot decide what ranges to use even with rather simple waveforms. It just jumps around. It would have been better for it to simply decide on something at some point, so it can at least display a stable waveform to the user.-No way to save startup settings. At least for me, this would have been much more important than the now existing ability to save waveforms.

author: saturation
author_rank: Super Contributor
timestamp: October 21, 2013, 11:42:55 am
content: Its OK to bump threads since electronics doesn't change, always good to get updates. I have the HPS40 which is the older model.See p.1 of this thread for a manual.The trigger indicator is a small "S" beside the waveform.I've not had trouble with autoranging on the HPS40.Yes, you cannot save startup settings except when configured from the setup menu.

author: grepas
author_rank: Newbie
timestamp: October 21, 2013, 12:28:19 pm
content: Quote from: saturation on October 21, 2013, 11:42:55 amOn the HPS140, that one just seems to indicate the trigger level, not whether the thing has been trigged or not.

author: hiddensoul
author_rank: Regular Contributor
timestamp: December 26, 2013, 01:07:17 am
content: I was doing some work with a friend who designs controllers. We were fitting a custom micro controller to a sawmill to replace all the old 4000 logic. All of the inputs and outputs from the new controller were done via optos for inputs and relays interfacing to the contactors for complete isolation from the old hardware. The lockout contactor was wired to an opto to prevent the carriage from moving sideways in to the band saw during a cut but the micro kept going from a lock to a safe state even when the contactor was pulled in by input from the operator. We chucked the Velleman across the opto and behold the power rail (12VDC) supplying the old hardware was only half wave rectified. The contactor was holding closed okay but it was freaking out the micro board input. A cap across the opto input and a bleed resistor fixed it. The scope found the problem in 30 seconds and paid for itself in labour savings right there, so was the perfect tool for the job...

author: Fraser
author_rank: Super Contributor
timestamp: December 26, 2013, 12:41:59 pm
content: Nice report.I have found the little 140i to be great for quick checks for situations just as you describe.She's a compact and useful little tool, if not a sophisticated DSO. I ended up with four of the units, all but one were bought on the secondary market very cheaply. None had received the firmware update that improves the triggering above 1MHz.

author: Hydrawerk
author_rank: Super Contributor
timestamp: May 02, 2015, 04:25:45 pm
content: I found a schematic of HPS140i.

author: Fraser
author_rank: Super Contributor
timestamp: May 02, 2015, 04:36:48 pm
content: @Hydrawerk,Great find. Thank youAurora

author: R_G_B_
author_rank: Frequent Contributor
timestamp: May 02, 2015, 06:46:32 pm
content: If only we could hack the firmware so that you could add single shot and other features this would make this handheld scope more useful.Anu chance of this happening?

author: R_G_B_
author_rank: Frequent Contributor
timestamp: May 02, 2015, 07:22:31 pm
content: And the function Generator:http://www.velleman.eu/images/tmp/HPG1%20technical%20doc%20V1.pdf

author: Fraser
author_rank: Super Contributor
timestamp: May 02, 2015, 07:27:32 pm
content: Velleman were very protective of their firmware last time I asked them about it.They also said they would not be releasing the schematics at that time as they "were not ready to do so with such a new design" (at the time I asked). I had to send my units back to Velleman for their firmware upgrade and have another four heading that way soon. It would have been so much easier to reprogram the MCU myself with the new code but I do not know whether calibration is then needed.This is the first truly technical information on the HPS140 I have seen to come out of Velleman.Aurora

author: R_G_B_
author_rank: Frequent Contributor
timestamp: May 02, 2015, 07:37:08 pm
content: Maybe they are planning on releasing another scope.The last two portable scopes HPS10 and HPS40 had schematics released not sure if they released the schematic some time after these two products went to market or at the same time.As for the firmware now theres a schematic maybe someone can reverse engineer it and add features.The main MCU is a microchip DSPIC. Is the firmware encrypted?

author: Leafy
author_rank: Newbie
timestamp: March 25, 2020, 12:45:22 pm
content: Ok I realize I'm bumping a thread from half a decade but this is probably the only concentration of HPS140 owners I'll find.Can anyone with this thing measure the barrel connector on the charger so I can figure out what I need to buy to charge mine? This information seems like a huge secret.

author: Fraser
author_rank: Super Contributor
timestamp: March 25, 2020, 12:51:09 pm
content: The unit comes with a USB based boost converter that increases the USB 5V to 9V. So you need a 9V d.c. power supply.I will dig out my unit today and see what current and polarity it requires.Fraser

author: Leafy
author_rank: Newbie
timestamp: March 25, 2020, 12:58:50 pm
content: Thanks, I believe I saw somewhere that the polarity is swapped from a normal barrel plug charger, at worst I can open up the unit and figure that out.

author: Fraser
author_rank: Super Contributor
timestamp: March 25, 2020, 01:51:08 pm
content: Power adapter is 9V 200mA centre positive on a 3mm OD barrel plug.Polarity confirmed as centre positive by multimeter test.Fraser

author: Leafy
author_rank: Newbie
timestamp: March 25, 2020, 01:52:32 pm
content: Do you have the ID?*Edit, looks like it better be 1.1mm or I'm shimming it anyways. Thanks a bunch.For anyone else in this predicament.https://www.mouser.com/ProductDetail/CUI-Devices/PP3-019?qs=sGAEpiMZZMtnOp%252BbbqA0023axwHuElQy2c5IhC1LWJ56KLiPljRvhA%3D%3Dhttps://www.mouser.com/ProductDetail/Phihong/PSM03A-090-R?qs=sGAEpiMZZMt5w6YCUaBPUYs%2Fw9Qhz%2FAu7NQ0q6hj7XA%3Dtotal will shipping was under $10

author: Fraser
author_rank: Super Contributor
timestamp: March 25, 2020, 02:32:56 pm
content: Sadly I do not have the ID.A 3mm OD normally has a 1.1mm ID though. Yer digital calliper confirms exactly 3mm OD on the barrel.Fraser