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Old 02-19-2018, 05:56 AM   #1
jarvis7
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Default Android Oscilloscopes , Cheap and good enough to test desktop PSUs reliably ?

Hello ,

I found some of these videos on youtube , it seems like a super cheap way of making oscilloscope , with some old spare android device

https://www.youtube.com/watch?v=xFA9CdusDWg

https://retronics.wordpress.com/2012...-oscilloscope/

i know they won't be super accurate but are these types atleast good enough to check Spikes and Ripple output of desktop PSUs to determine whether PSU is outputting Safe and stable voltage quality reliably ?

any experiences, thoughts , comments ?

Thank you ..

Last edited by jarvis7; 02-19-2018 at 06:49 AM..
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Old 02-19-2018, 08:15 AM   #2
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Default Re: Android Oscilloscopes , Cheap and good enough to test PSU ?

it's not about accuracy for most tests, it's about being fast enough.

i would say you need 200-500KHz - preferably 500+ to check for ripple on a psu, because most run at 60-80KHz and you need 5x that to get a good capture.

so it's going to depend on the maximum bandwidth of the phone you use.
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Old 02-19-2018, 10:09 AM   #3
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Default Re: Android Oscilloscopes , Cheap and good enough to test PSU ?

Agreed. In general these "sound card oscilloscopes" are only good for ... sound.

Therefore, good only for debugging audio problems, and possibly linear PSUs.

Ugh, I can't believe that guy in the video that got rid of their bench scope "for bench space," must not be serious of an experimenter or assumes there will be an IC that will handle all the high frequency stuff...
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Old 02-19-2018, 04:46 PM   #4
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Default Re: Android Oscilloscopes , Cheap and good enough to test PSU ?

Quote:
Originally Posted by eccerr0r View Post
Agreed. In general these "sound card oscilloscopes" are only good for ... sound.

Therefore, good only for debugging audio problems, and possibly linear PSUs.

Ugh, I can't believe that guy in the video that got rid of their bench scope "for bench space," must not be serious of an experimenter or assumes there will be an IC that will handle all the high frequency stuff...
When you need to get rid of your scope for "bench space" you need a bigger bench.
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Old 02-19-2018, 05:45 PM   #5
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Default Re: Android Oscilloscopes , Cheap and good enough to test PSU ?

Quote:
Originally Posted by eccerr0r View Post
Agreed. In general these "sound card oscilloscopes" are only good for ... sound.

Therefore, good only for debugging audio problems, and possibly linear PSUs.
^This,

I see the OP doesn't list a location, if you're in the US <$50 analogue scopes are pretty easy to come by (especially brands other than Tektronix and HP, you'll often need to add you're own probe, but the <$10 eBay/Amazon probes work fine), most you'll find in this price range are 10-30mhz, but that is more than enough for PSUs.

There are also the $20-30 kits on eBay/Amazon/etc., though they're only rated for 200Khz (and often don't perfrom well above 100Khz) so still definitely on the low side for PSU ripple, but better than a sound-card based scope (most phone sound cards aren't going to handle anything above 20 KHz).

Last edited by dmill89; 02-19-2018 at 05:46 PM..
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Old 02-20-2018, 01:19 PM   #6
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Default Re: Android Oscilloscopes , Cheap and good enough to test PSU ?

I was thinking about selling my old 20MHz scope, because I'm out of bench space

( but I can say that because I have two other 300MHz scopes...
Alas, this 20MHz scope can run on 12VDC whereas the two Teks cannot without an external inverter...)
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Old 02-20-2018, 03:14 PM   #7
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Default Re: Android Oscilloscopes , Cheap and good enough to test PSU ?

So , not useful at all then for PSU..

Thank you very much Stj , eccerr0r , clearchris , dmill89 sir

Last edited by jarvis7; 02-20-2018 at 03:18 PM..
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