Cheap Oscilloscope - Page 1
Forum section: electronics / beginners

author: SupremeFX
author_rank: Newbie
timestamp: August 30, 2011, 01:47:40 am
content: Hi,I was looking for a cheap Oscilloscope these days (not really meant to be bought now but maybe later).I'm not looking for a kick ass 5k$ tektronix , no in fact I'm just looking for something that can pick up 1 or 2 channel on 24 volt dc maximum.I want it basically for learning more and do some little troubleshooting.The first thing i was told to check some Ebay Pc oscilloscope , but i read on net that some people doesn't recommended those at all...So i was just wondering if anyone know cheap alternative for low power oscilloscope?Maybe better Pc Oscilloscope somewhere?

author: Computeruser
author_rank: Regular Contributor
timestamp: August 30, 2011, 02:02:19 am
content: I purchased two oscilliscopes on eBay and I am happy with them both. In one case, I spoke to the seller on the phone; in both cases, I had the right of return if I was not happy.So if you have your wits about you and a good measure of common sense, you can buy on eBay. Make certain you can return the instrument if you do not want it (that is, does not work to your reasonable satisfaction or as stated on the auction).There are risks, of course, but it can be done. ... C

author: ivan747
author_rank: Super Contributor
timestamp: August 30, 2011, 02:14:37 am
content: A Velleman HPS10 will do. You can pick these things up for down to $115. I saw a clearance offer the other day on Tequipment where they has the plus edition cheaper than the regular one.

author: EEVblog
author_rank: Unknown
timestamp: August 30, 2011, 04:24:11 am
content: Get a 20MHz dual channel analog scope off ebay. Almost any brand will do the trick.Then learn how to check it:Dave.

author: seb
author_rank: Newbie
timestamp: August 31, 2011, 04:12:55 pm
content: Dave's right. Look on eBay or in electronic magazines.I started with the HAMEG 203-6. Its a two channel 20 MHz analog Scope manufactured in 1987 and it works very well. It's a good quality basic scope which you can get on eBay for less than 100 $.

author: Zero999
author_rank: Super Contributor
timestamp: August 31, 2011, 05:41:24 pm
content: Quote from: ivan747 on August 30, 2011, 02:14:37 amYou can't be serious? Little 'scopes like that are only any good if you need an isolated 'scope. Otherwise they're very limited being single channel limited to under 10MHz and have a low resolution display.I think you're better off spending just a little more on a cheap Chinese 'scope.http://www.ebay.co.uk/itm/New-ATTEN-Digital-Oscilloscope-ADS1062C-60MHz-2-Channel-/220827956120?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item336a5f3398http://www.ebay.co.uk/itm/New-Atten-Digital-Oscilloscopes-60MHz-ADS1062C-500MSa-s-/130503498248?pt=BI_Oscilloscopes&hash=item1e629d5a08http://www.ebay.co.uk/itm/ATTEN-ADS1022C-Digital-Storage-Oscilloscope-25MHz-50Msa-/220827960701?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item336a5f457dhttp://www.ebay.co.uk/itm/ATTEN-Digital-Oscilloscope-DSO-ADS1062-ADS1062C-60Mhz-/290409296227?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item439dbe3163

author: thilo
author_rank: Regular Contributor
timestamp: August 31, 2011, 06:48:48 pm
content: Quote from: SupremeFX on August 30, 2011, 01:47:40 amAre you talking about 24V peak-to-peak or 24V rms here?

author: Unknown
author_rank: Unknown
timestamp: August 31, 2011, 08:08:38 pm
content: I second the analog scope. It will be a lot more useful than a toy scope like the Velleman or DSO Nano. There's just not a lot of options between the bottom-end 'real' scopes like the Rigol DS1052E and the toy scopes like the DSO Nano.

author: elliott
author_rank: Regular Contributor
timestamp: September 01, 2011, 02:09:47 am
content: Check your local classifieds, I just picked up an old BK Precision 2120 that I found on Craigslist. It looks brand new and came in the original box. I checked it out the best I could and took it home for $80. I might have been able to get one on eBay cheaper, but having the ability to check it out in person before buying was worth it.Only thing I can't figure it out is why it is black, every other one I've seen online is white.

author: vk6zgo
author_rank: Super Contributor
timestamp: September 01, 2011, 02:11:26 am
content: I agree,buy an analog 'scope.You will save yourself a heap of frustration,(once you've learnt how to use it),as pretty much,an analog unit or a good bench DSO "does what it says it does",whereas the published specs for most of the low end digital devices are very selective--only showing those specs which cast the device in a good light.These "cheapie" digital units have severe limitations in performance,which will disappoint you in use.To bring out my "hobbyhorse" for a run,I'll point out that these units reduce their sample rate as the time/div scale is increased,until at say,5ms/div,you cannot look at a PAL or NTSC video field accurately,due to horrific aliasing problems.This is an easy test to do,as most DVD players,set top boxes etc,provide a stable source of composite video.This problem is not just applicable for video signals but applies in any case where you may be looking for mains hum on a high frequency signal.VK6ZGO

author: Bored@Work
author_rank: Super Contributor
timestamp: September 01, 2011, 05:56:29 am
content: Quote from: vk6zgo on September 01, 2011, 02:11:26 amWhich you can work around by sampling with a lower time/div, and then use the "zoom" function of your scope. If your cheap scope has one. And if it it is easy to operate without wading through all kinds of strange menus. And if zoom not only works in single shot.

author: ejeffrey
author_rank: Super Contributor
timestamp: September 01, 2011, 09:26:45 am
content: And assuming your cheapie scope has deep enough memory.

author: vk6zgo
author_rank: Super Contributor
timestamp: September 02, 2011, 07:10:21 am
content: Quote from: ejeffrey on September 01, 2011, 09:26:45 amYeah!I wasn't talking about looking at individual lines in the field.To look at mains hum or clamping error on a PAL video signal,you need to display the full 20m/s of the field.The maximum luma frequency of the PAL system is 5MHz (In Australia & Europe,in the UK,it is 6MHz).This implies a sample rate of 10MS/s at least.The device then has to remember 20ms worth of that second,which is 2x10^5 samples.The Tek & HP 'scopes that were demonstrated at my workplace back in the 1990s were not capable of displaying video at field rate.Just before I left there,we were having a lot of trouble with the last new analog 'scope we purchased from Tektronix,& eventually we were offered one of the first "pretty lunchbox" type digitals.This did the job--almost!!Despite what I said above,there is a bit of "wriggle-room" with video signals,in that there isn't a lot of energy in the highest frequency luma components,so we can get away with a slightly lower sample rate----for the luma component!A field rate signal displayed with this device was pretty good,except for a low frequency component drifting through the display,due to the sample rate being too low to faithfully reproduce the fairly high energy, chroma signal at 4.433MHz.It was quite usable,given the funny "sprog" in the display.For NTSC, it would have probably been excellent,bearing in mind the 16.666ms field duration & approx 3.6MHz chroma frequency of that system.I haven't really had much to do with digital Oscilloscopes since leaving that job,but I assume that the modern moderately priced bench 'scopes(Rigol,etc) are able to pass this test OK,but I was casting doubt on the "El Cheapos".There is a workaround which can be used to look for hum with analog 'scopes,if for some reason you don't want to change to field rate.Look at "back porch" noise at line rate,then "zoom in"(OK,the function isn't quite the same,but its effect is similar), on the noise to see if it is high frequency.If the HF noise is minimal,the rest of the noise is hum.I'm not altogether sure this would work with a digital 'scope though!VK6ZGO