help a newb with an oscilloscope question?

Started by pinkjimiphoton, October 25, 2012, 11:59:49 AM

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pinkjimiphoton

hi guys, trying to debug my little rebote, which i absolutely love. started a thread about the weirdness i've encountered:

http://www.diystompboxes.com/smfforum/index.php?topic=99676.0

so...my question is...one of them "will this work???" questions.

if i put an audio signal in the input, say with my brother's ipod, and then use my o-scope to look at the waveform, and "reverse" audio probe it with the probe from the o-scope from input jack to output, if i suddenly see a drastic change in the waveform, will that help me find the problem i'm having?

i know it's a dumb question, but i've never used the scope before, despite having it for years...and old techtonics 310 i think it is...

but i'm stumped, and trying to think outside the box to find the problem described in the linked thread.

thanks!!
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R O Tiree

It certainly will, Jimi.  It won't tell you why it's happened, merely that it has and where it has, which will enable you to narrow things down.
...you fritter and waste the hours in an off-hand way...

pinkjimiphoton

thanks mike, i'm gonna get on it after supper.
  • SUPPORTER
"When the power of love overcomes the love of power the world will know peace."
Slava Ukraini!
"try whacking the bejesus outta it and see if it works again"....
~Jack Darr

cpm

i built a small oscillator in a scrap of breadboard, with some filtering so it resembles a sine wave, about 1khz and 1volt amplitude.
i use this to "see" the waveforms through the circuit, sending the signal to the input, and poking around with the scope. So not only to debug, also to see posible headroom problems, distortion characteristics, adjust trimpots, whatever. Now I hardly use a standard voltage meter, i usually have the oscilloscope setting the vertical axis to the power rails and just probe here and there...
now i cant live without it...

mattthegamer463

I do this all the time and I find that strumming an open E works well to make a sine-like wave thats easy to see on the scope. Constantly having to re-pluck the string is annoying though.  If you have the bits around, make a small LFO.

pinkjimiphoton

i'll use my ugly face as an oscillator, thanks for the tip guys!! :icon_smile:

if i can't find the problem after this, man, i dunno if it's fixable.  :icon_eek:
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"When the power of love overcomes the love of power the world will know peace."
Slava Ukraini!
"try whacking the bejesus outta it and see if it works again"....
~Jack Darr

Gurner

There are also (free) android 'signal generator' apps too, just output the sine wave on your phone's headphone socket as the source signal into your circuit.

pinkjimiphoton

  • SUPPORTER
"When the power of love overcomes the love of power the world will know peace."
Slava Ukraini!
"try whacking the bejesus outta it and see if it works again"....
~Jack Darr