Tight budget, first scope. - Page 1
Forum section: electronics / beginners

author: davelectronic
author_rank: Frequent Contributor
timestamp: January 10, 2024, 05:46:58 pm
content: I'm a newbie to scopes, but need one to look at linear power supply output waveforms. My budget is really tight at the moment, I've found a hand held scope / multimeter, although it's the scope I need the most for fault finding. This is the link to what I found, reviews look good, it's available in 50mhz and 100mhz versions. I'm wandering if it's suitable for measuring linear power supply outputs waveforms.Thought appreciated, thanks for reading.HANMATEK Handheld Digital Oscilloscope 50Mhz Bandwidth with 2 Channels HO52 3.5"TFT Mini Oscilloscope, 2 in 1 Oscilloscope and Multimeter, Backlit Screen, Auto-Calibration Function, Memory Functionhttps://amzn.eu/d/fRbbzop

author: Vovk_Z
author_rank: Super Contributor
timestamp: January 10, 2024, 07:22:12 pm
content: Both 50 MHz and 100 MHz frequency ranges are totally fine for DIY, if you are not interested in high-speed design. I would say that true 20 MHz range scope would be fine for me in 99.999% cases. 20 MHz range limit is typical for analizys of SMPS devices.

author: davelectronic
author_rank: Frequent Contributor
timestamp: January 10, 2024, 07:51:52 pm
content: Thanks for looking, and helping. I will go with the 50mhz version of the scope I posted in the link. I'd like a Rigol or similar, but that's out of reach at the moment. There are old school scopes on eBay, but it's knowing if your getting one in full working order. Even though I have dabbled in electronics for some years, I still think I'm a novice. Repairing a second hand scope is beyond my ability.

author: tggzzz
author_rank: Super Contributor
timestamp: January 10, 2024, 11:50:35 pm
content: Don't forget the cost of the probes, nor any other equipment.If money is is tight, then for your purposes virtually anyworkingscope will be sufficient. Nowadays old second-hand scopes are widely available, and a rule of thumb is £1/MHz. Since 10MHz is more than sufficient for looking at a linear PSU, you might be able to save money.Be aware there are many types of probe; seehttps://entertaininghacks.wordpress.com/library-2/scope-probe-reference-material/

author: tatel
author_rank: Frequent Contributor
timestamp: January 11, 2024, 12:00:35 am
content: The link you provide bears an "Currently unavailable" warning.In addition, I don't know about that Hanmatek model but toyscopes in that category usually have specifications that have to be taken with a grain of salt. There are threads about (toy) scopes on this forum. Please seehttps://www.eevblog.com/forum/testgear/portable-oscilloscopes-list/msg5194335/#msg5194335Owon and Zeewei have models that could do something with a power supply but be aware that at least Zeewei models are unable to do a differential measurement, which is something you'll probably would consider an interesting feature when looking at power supplies.Personally, while already having a 4-channel, 100 MHz digital scope, I bought a Hameg scope on eBay just to look at power supplies. Actually I bought more than one. You should look for afully functional20 MHz Hameg or similar. You'll probably be able to find something on UK even cheaper than in EU. Something like this would be adequate IMO (sorry about the spanish links):https://www.ebay.es/itm/134858484348?orhttps://www.ebay.es/itm/404731057803?Now I don't have to worry about destroying my DSO,and this 50-100€, analog scopes are enough to fulfill your stated needs.Edit: I wouldn't pay more than 120€ plus shipping, customs, etc (sellers often ask for preposterously high prices). However you could find a bargain in about 6 months time. Perhaps you could even get a good 60 Mhz one (Hameg 604 or, better, 605) in that price range and time window. A good-working Hameg would do all you need without any glitches whatsoever, while most of the digital, portable, cheap new ones have some drawback. That's the reason I would rather go for a Hameg than one of these new ones. Even if it costs a bit more. Good luck.Edit2: it seems that Owon HDS242 is able to invert channels and do the math, so there you have the "poor's man differential measurement". Please see pages 30-31-32 of the manual:https://www.manualslib.com/manual/455289/Owon-Hds-Series.html?page=30#manualSo, in a hurry, I would go with Owon HDS242, probably. IIRC, I have seen some reports about some HDS model(s) running hot and being somewhat unstable. Having time, I would look for some old analog Hameg instead.Sorry, Google lied to me and this manual seems to be for a higher HDS modelNow, I also own a Zeeweii DSO154Pro. Just one channel, and, say, 10 usable MHz bandwidth, open case. Max input voltage 40V with 1X probe, 400 with 10x probe. But it could be enough (it is enough to do what I want it to do for me), and it would set you just some 50 quid back, probably with one probe included (look in AliExpress). Since higher Zeeweii models are unable to do differential measurements, I don't see any need to get one of these. To design a 2-channel device that does some kind of poor FFT but unable to invert a channel, then add the other, looks stupid to me. YMMV

author: dobsonr741
author_rank: Frequent Contributor
timestamp: January 11, 2024, 04:20:06 am
content: Scope buying is fun, as it should be. However, can you tell more about your measurement scenario? What and why would you measure on a linear power supply with a scope?

author: pickle9000
author_rank: Super Contributor
timestamp: January 11, 2024, 05:52:59 am
content: If you are a beginner, working with power supplies a handheld is a good choice.If it has a charger or USB don't use either (Unplug) while taking measurements.

author: Berni
author_rank: Super Contributor
timestamp: January 11, 2024, 06:21:23 am
content: One of these handheld scopes can also be a good idea:https://eleshop.eu/owon-hds272-handheld-oscilloscope.htmlThey can get some proper sample rates and waveform update rates on these things now, so you are not missing out on that much functionality compared to a cheap bench scope. This one can even get you a built in signal generator. The fact that it is battery powered also means you don't need to worry about blowing it up due to ground loops.You would certainly still want to upgrade to a real proper scope in the future if you end up really getting into electronics, but this little thing can still cover the majority of typical scope uses.EDIT: There are a few good portable scope models out there. This Owon is just one that i personally own and think it is a good deal.

author: pickle9000
author_rank: Super Contributor
timestamp: January 11, 2024, 06:37:00 am
content: Quote from: Berni on January 11, 2024, 06:21:23 amYup I have one too a perfectly OK scope.

author: davelectronic
author_rank: Frequent Contributor
timestamp: January 11, 2024, 12:33:33 pm
content: I'm in the UK, there are a couple of old Hameg scopes on eBay at the moment, 20mhz to 60mhz, but I've got an old Hameg 60mhz scope, but it's not working properly. The traces are short at each side of the screen. It could probably be calibrated, but I'd have to find some where to do it, and then there's the carriage costs. A hand held budget scope has appeal being portable, and the price isn't to bad. I plan to use it when it appears a PSU circuit regulator is ocillating, and other problems with the circuit output. At the moment I have a linear power supply but don't know why the output is dropping nearly a couple of volts under load. Its powering a linear amplifier load, I suspect it's effecting the linear voltage regulator, and with no scope, I haven't a clue what is going on. I've sort some advice on the forum here, which has been very helpful. Yet with out seeing the output wave form, I can't be certain what's going on. This is the main reason for needing a scope, plus I would imagine it will come in handy for other projects. But mainly it's for looking at linear power supply outputs.

author: tggzzz
author_rank: Super Contributor
timestamp: January 11, 2024, 02:52:37 pm
content: Quote from: davelectronic on January 11, 2024, 12:33:33 pmFirst debugging with old equipment (a scope or a PSU or an amplifier) is to visually inspect each and every electrolytic capacitor for signs of leakage.Second check the internal power supplies for voltageand ripple. Both can be done with a normal DVM.If the ripple is excessive, check the electrolytic capacitors. This may involve removing them and checking the ESR with a cheap "naked PCB" component tester.After that start considering more exotic problems.

author: dobsonr741
author_rank: Frequent Contributor
timestamp: January 11, 2024, 04:54:14 pm
content: QuoteThx for the context. While the scope is a good tool, it will only be helpful if indeed there's a parasitic oscillation or the filter capacitor has way too much ripple. You can check for both with a DMM in AC mode, and can do static load test without the amplifier on the power supply. Just b/c you mentioned budget.The scope is a good investment, however, this buying decision now might make you buy a scope optimized for this rather marginal use, whereas later you might have a situation you need a scope for a more demanding problem, where this one you buy now might not be good enough, and you ended up with a week one, and possibly need to buy a new.

author: tatel
author_rank: Frequent Contributor
timestamp: January 11, 2024, 05:05:24 pm
content: Even Zeeweii DSO154Pro will be able to show if that PSU is oscilating, but Owon HDS 242-272 is a much more robust device that will be able to do many things for you in the future, perhaps in places where you wouldn't go with your benchtop 60 MHz Hameg.tggzzz: is that what you mean?https://www.amazon.com/Multifunction-Transistor-Capacitance-Frequency-Generator/dp/B0BNDY8ZP9/ref=sr_1_16?keywords=component+tester&qid=1704992093&sr=8-16Edit: link

author: tggzzz
author_rank: Super Contributor
timestamp: January 11, 2024, 05:26:05 pm
content: Quote from: tatel on January 11, 2024, 05:05:24 pmThat's the kind of thing, but I don't know about that specific device. I would like to see the displayed values and ESR mentioned more prominently.

author: davelectronic
author_rank: Frequent Contributor
timestamp: January 11, 2024, 06:35:16 pm
content: All the components in the PSU are brand new, I built it. The linear PSU 12.70 Volts output happily runs a resistive 100 watt halogen lamps load, but plays up driving a 100 watt HF linear amplifier. By dropping nearly 2.0 volts under load. ( Other thread in projects section) I was asked what the output, and filtered DC looked like with a scope. I don't have a functional one to hand. Most of the loads I run are HF radio related items, radios, amplifiers and such. I'm running the amplifier with a PSU I built that does it well. But I have other power supplys that play up on the same amplifier and radio combinations. I figured I need to see what is going on with a scope. In the other thread, members have given me possible solutions to stop the power supply dropping voltage like it is. Taking some readings before, and after trying these solutions seems a good idea. I can avoid problems in the future, if I can find the problem.

author: tatel
author_rank: Frequent Contributor
timestamp: January 11, 2024, 07:50:43 pm
content: Quote from: tggzzz on January 11, 2024, 05:26:05 pmIt's a well-known player from this massive (361 pages and counting) thread:https://www.eevblog.com/forum/testgear/$20-lcr-esr-transistor-checker-project/I know you are not a fan of any videos, but for other people, Dave made this video:At 7:22 mark you can see the most basic one compared to an Agilent U1733C with ESR measurement included, all in about one minute time.Assuming OP doesn't have anything of this kind, at that price, I would be quite sensible to get one, specially on a tight budget. Even if the caps on these power supplies he's building are brand new. Perhaps these caps have been on a shelf for long time...Anyway it would be good to ask for a recommended provider on that thread; on the last couple of years knock-off have appeared, which can't take the firmware developed by people on that thread. IIRC

author: tggzzz
author_rank: Super Contributor
timestamp: January 11, 2024, 07:59:48 pm
content: Quote from: davelectronic on January 11, 2024, 06:35:16 pmOK. Time for you to stop posting partial information here, and partial information somewhere else.

author: davelectronic
author_rank: Frequent Contributor
timestamp: January 11, 2024, 09:54:04 pm
content: My post here is asking opinions on handheld scope I found, as I'm on a budget. The mention on another post / thread was to explain the reason I was looking for a scope, be it on that budget. I'm not posting bits of information here and information there. This thread is about a budget scope, the other thread in another section is asking for help with a PSU I built dropping to much voltage. I'm not talking about the other thread, I briefly explained why I think I need a budget scope. No need to troll is there. Nevermind I don't have a problem with anyone. I appreciate the ideas and suggestions by kind members that have been made to me.

author: davelectronic
author_rank: Frequent Contributor
timestamp: January 11, 2024, 10:06:00 pm
content: HANMATEK Handheld Digital Oscilloscope 50Mhz Bandwidth with 2 Channels HO52 3.5"TFT Mini Oscilloscope, 2 in 1 Oscilloscope and Multimeter, Backlit Screen, Auto-Calibration Function, Memory Functionhttps://amzn.eu/d/bRAnOJFJust tried the link again to the scope I'm probably going to go for. It's on Amazon for £129 I'm not expecting bells and whistles, but from the advice I've read so far, and my limited knowledge, hopefully this will do the job. Thank you all for your help.

author: tatel
author_rank: Frequent Contributor
timestamp: January 11, 2024, 10:49:39 pm
content: New link still bears "Currently unavailable. We don't know when or if this item will be back in stock."From the HDS242 thread it turns out this Hanmatek HO52 is a rebranded HDS242See:https://www.eevblog.com/forum/testgear/owon-hds-200-handheld-oscilloscope-w-builtin-dmmawg/msg5065804/#msg5065804It's up to you, but I would go with the original. Owon's firmware upgrade on these devices isn't straightforward, but even so, it seems to be better than the support Hanmatek gives (probably near zero). Also, should you have a pure HDS242, there is a community here that owns it; with Hanmatek, you'll probably will be alone. A search for "Hanmatek HO52" on this forum return just six results.Again, its up to you.

author: tatel
author_rank: Frequent Contributor
timestamp: January 11, 2024, 10:58:17 pm
content: Both are on Banggood: Hanmatek HO52 for 120€, Owon HDS242 for 98€. Now you know what business model is Hanmatek'shttps://es.banggood.com/HANMATEK-H052S-H052-Professional-Handheld-Digital-Oscilloscope-50MHz-250MSa-or-s-with-Multimeter-Signal-Generator-USB-Type-C-Interface-Advanced-Testing-Tool-p-2000297.html?cur_warehouse=CN&ID=471846324524&rmmds=searchhttps://es.banggood.com/OWON-HDS200-Series-2CH-Handheld-Oscilloscope-40-or-70-or-100MHz-Bandwidth-20000-Counts-Multiumeter-OSC-+-DMM-+-Waveform-Generator-3-in-1-Suitable-for-Automobile-Maintenance-and-Power-Test-p-1802427.html?rmmds=detail-topright-recommendation&cur_warehouse=CN&ID=6301777&trace_id=7e091705013627690

author: davelectronic
author_rank: Frequent Contributor
timestamp: January 11, 2024, 11:03:22 pm
content: Sorry the link didn't work again, if I can find a supplier for the Owons scope, certainly I'd go with a product with a bigger following. But on the lower end budget, the hand held scopes are probably built down to a price. I'm a hobbyist, so it won't see hard or heavy use, it's only to see what a few linear power supplys put out from a voltage regulator and a few power transistors, fashioned into a usable power supply. Thanks for posting though.

author: Berni
author_rank: Super Contributor
timestamp: January 12, 2024, 06:13:54 am
content: Even for hobby use do not underestimate just how horrible chinese made firmware can be.I bought some Hantek brand signal generator at once point for a really good price brand new. The specs were great. Dual channel 16bits, nice high sample rate, lots of output swing..etc. The PCB inside also looked well made. Yet when i got it the channels were dead, eventually got them to give me a firmware update that fixed it. It did generate some nice looking signals but the UI was still a buggy mess. Heck sometimes the output enable button would not work (it lit up as if the output is on, but it is off, then you turn it off and turn it on again and there is output again). The more advanced features like modulation were glitchy too. Some combination of those settings would even crash it, causing it to reboot, however if you have it to remeber the last configuration it will load that config right back up and crash again, making it infinitely boot cycle until you go trough the secret key combination for doing a factory reset. Tried some other firmware versions, they fix some stuff but break other stuff, so not much help.Quickly ended up selling that piece of crap to a coworker who was really interested in it (likely due to the nice specs), but later on he also found out how horrible it actually is to use.So badly made firmware can most definitely completely ruin an otherwise great product.

author: davelectronic
author_rank: Frequent Contributor
timestamp: January 12, 2024, 05:06:09 pm
content: Yes I had read from posted links that some firmware was problematic. I have found the Owon 40mhz scope now, it's on Amazon for £126 The reviews look good, I'm not expecting much for that figure. But hopefully it can bridge the gap, at least until I can find a better quality bench scope, like the Rigol range suitable for hobbyists. The hand held scope, be it cheap, just gets me going for now, so I can look into this PSU voltage drop problem.

author: p.larner
author_rank: Frequent Contributor
timestamp: January 14, 2024, 08:37:21 am
content: is the psu using a 731 vreg?,are you sure its not rf screwing its control loop up?,that would be my guess.73.

author: davelectronic
author_rank: Frequent Contributor
timestamp: January 14, 2024, 12:29:10 pm
content: I'm using a 7812 1 Amp voltage regulator. I think it's RF as well, I've made some decoupling adjustments from the PCB to the chassis. And added some additional capacitance to the output. I'm yet to try it hopefully today. And if that still plays up, I will look at it with a scope to try and work it out. I've gone with a budget Owon HDS242 hand held scope.

author: tggzzz
author_rank: Super Contributor
timestamp: January 14, 2024, 01:23:42 pm
content: Quote from: davelectronic on January 14, 2024, 12:29:10 pmShow us a photo of the implementation. Long wires and solderless breadboards are fertile ground for strange unrepeatable behaviour.Some linear regulators oscillate with too much capacitance on their output. Either reduce the capacitance or insert a damping resistor (tant bead capacitors used to be popular because they have non-zero ESR).

author: davelectronic
author_rank: Frequent Contributor
timestamp: January 14, 2024, 01:40:54 pm
content: I will post a picture in the thread where I asked for help with the voltage drop problem. It's in the design section, I used Vero FR4 gold plated board. The traces are 1.5mm solid copper wire, or solid thick solder traces on the plated track side to carry the current. I haven't used a bread board for testing, it can't carry the 10 Amps I will load the circuit down with. If it does play up again, I should have a scope very soon to look at the unstable voltage dropping output.

author: tggzzz
author_rank: Super Contributor
timestamp: January 14, 2024, 01:53:03 pm
content: Quote from: davelectronic on January 14, 2024, 01:40:54 pmBollocks.I forgot I had previously given you A Big Hint as to etiquette.https://www.eevblog.com/forum/beginners/tight-budget-first-scope/msg5273571/#msg5273571BTW, your points are irrelevant to the potential issues I noted. (E.g. the current carrying capacity of those inductors is irrelevant; their inductance is relevanthttps://chemandy.com/calculators/round-wire-inductance-calculator.htm).

author: davelectronic
author_rank: Frequent Contributor
timestamp: January 14, 2024, 05:23:32 pm
content: I'm going to ignore anymore posts from you, I find your manner very rude. I haven't a clue as to what inductors your referring to. I'm not using inductors. Any further post you make will be ignored, your clearly trolling for an argument. Not with me pal.

author: tggzzz
author_rank: Super Contributor
timestamp: January 14, 2024, 05:56:08 pm
content: Quote from: davelectronic on January 14, 2024, 05:23:32 pmThe link I gave will allow you to calculate the value of the inductors you have told us you are using.

author: Simon
author_rank: Unknown
timestamp: January 14, 2024, 06:04:11 pm
content: If you want to help why not answer the other thread?

author: tggzzz
author_rank: Super Contributor
timestamp: January 14, 2024, 06:52:49 pm
content: Quote from: Simon on January 14, 2024, 06:04:11 pmWhichother thread? (How many active threads are there?)If you look at my responses in this thread you will see that I have answered people who have provided information.In addition, several times I provided help and pointers to the OP,which he chose not to consider. Horses, water, and all that.

author: rhb
author_rank: Super Contributor
timestamp: January 14, 2024, 08:15:59 pm
content: I've been evaluating this from the perspective of someone with a vast suite of high end kit.Take a very serious look at the Hanmatek DOS1104. It has a no BS 140MHz AFE, first rate FFT (though with incorrect labels) and can be had via Aliexpress for under $200 USD.It is NOT suitable for anything other than analog work because of the short memory, but it's really good for HF ham radio work.My testing has used one of Leo Bodnar's superb pulsers and a noise source. The latter and the FFT showed the AFE response very clearly.BTW it's an Owon rebrand. I am working on converting mine to LiPo power. It needs 1.7 A @ 5 V which is more than the BMS/boost convertors I've tried so far. The MT3608 generates far too much heat going from 3.7 to 5 V at 1.7 A and as the LiPo voltage drops the increasing current draw causes the BMS to shutdown.The next iteration will use a 2S BMS and a buck convertor.Have Fun!Reg

author: rhb
author_rank: Super Contributor
timestamp: January 14, 2024, 08:23:42 pm
content: Quote from: davelectronic on January 11, 2024, 10:06:00 pmI can't speak for the Hanmatek, but I have a Hantek which is pure crap and and Owon HDS272S. The Owon is quite nice and does what it says. Only serious downside is the UI is hobbled by the form factor. The Hanmatek is almost certainly an Owon rebrand. The Owon is part of my Field Day test bench.Have Fun!Reg

author: rhb
author_rank: Super Contributor
timestamp: January 14, 2024, 08:47:37 pm
content: Quote from: davelectronic on January 14, 2024, 05:23:32 pmSorry to have to tell you this, but you are *way outside your lane*. You are sufficiently ignorant of very basic electronics as to be unable to use *any* assistance. When you get an answer you don't understand it. Go read some books. *Every* conductor is an inductor.Had I read the thread I'd never have posted a reply.Reg

author: davelectronic
author_rank: Frequent Contributor
timestamp: January 14, 2024, 11:50:11 pm
content: I meant I wasn't using any inductors in the circuit build, I didn't say the load wasn't and inductive type. Well it's probably inductive and resistive. I read a lot of electronic articles, when I come across them. Although I know I'm still a novice hobbyist, that's why I asked questions on a budget scope to fault find a power supply dropping what I think is a bit much voltage. I ended up with the Onwon HDS 242 scope, I've not used it yet, but it looks nicely built. The interface seems suitable for a non professional hobbyist. Probably my last post here, I have taken in everything that has been said to me by posters in this, and my other thread. Which I will post the outcome of the suggestion put to me that I've implemented. Thank you for all your help on thoughts on a budget scope. And I don't delude myself, I have got loads to learn.PS. I take in every post that appears, if I don't reply exclusively to a post doesn't make me ignorant. I think some people force there opinions on OP's and if they don't respond, they go off on one. I've read all the posts, and wasn't happy with one members rude behaviour, that doesn't make me ignorant. I've got no time for narcissistic traits in some individuals. Thanks again for the help.

author: tggzzz
author_rank: Super Contributor
timestamp: January 14, 2024, 11:56:33 pm
content: Quote from: davelectronic on January 14, 2024, 11:50:11 pmIf you have a 6"/150cm piece of wire in your circuit, then you also have a ~150nH inductor in your circuit. Bad news, especially in a ground lead for a voltage regulator. if not, then you have made your fortune

author: rhb
author_rank: Super Contributor
timestamp: January 15, 2024, 02:28:47 pm
content: I'd like to suggest the OP buy an older edition of "Electronic Principles" by Albert Malvino. I worked my way through the 2nd ed many years ago recording all my work in a bound quadrille ruled notebook. I've not seen it since Baker took over updating the book, but was horrified when a friend paid $200+ for the current edition when older editions are $5-10. Every edition is different as things get dropped to make room for new devices.There are numerous basic circuits and Dr. Malvino builtevery oneto verify that no typos had crept in. Not many authors care that much about their readers.All real world conductors have resistance and induction if there is current flowing. And is capacitively coupled to every other conductor in the circuit if there are potential differences. These are generally referred to as "parastics" and they are the bane of everyone who designs and builds electronic circuits.The OP did make a good decision on the Owon HDS242, though the S version with the AWG would have been a better choice for not that much more.Have Fun!Reg