DIY Oscilloscope? ($20-30)

Monkey Bytes

New member
https://youtu.be/x19kwG-wJRI

Would something like this do the necessary functions for troubleshooting clock signals and data lines? If so, $30 and 3 hours of my time will be much more manageable than $300+ for a real oscilloscope.

This guy also has a video on making a variable lab bench power supply with $30-40 in parts & he mentions being able to modify a desktop power supply to serve the same purpose. I may go ahead and purchase both oscilloscope and power supply kits just to test it - for hobbyist purposes as well as board repair diagnostics.

I know Clock/Data signals are a pain without an oscilloscope, and Louis mentioned in a video that having a bench power supply is useful for troubleshooting traces and other unusual power troubles.
 
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G.Beard

New member
https://youtu.be/x19kwG-wJRI

Would something like this do the necessary functions for troubleshooting clock signals and data lines? If so, $30 and 3 hours of my time will be much more manageable than $300+ for a real oscilloscope.

This guy also has a video on making a variable lab bench power supply with $30-40 in parts & he mentions being able to modify a desktop power supply to serve the same purpose. I may go ahead and purchase both oscilloscope and power supply kits just to test it - for hobbyist purposes as well as board repair diagnostics.

I know Clock/Data signals are a pain without an oscilloscope, and Louis mentioned in a video that having a bench power supply is useful for troubleshooting traces and other unusual power troubles.

Those DSOnano(s) and DSO kits are toys. Yes you can see a waveform but bandwidth, resolution, memory depth and a whole bunch of other shit should be concidered. You would be better off getting an old CRT analog scope from eBay like a 25MHz or 50MHz analog scope. If you have a small workbench you can sit them upright next to your chair on the back rubber feet.... Mate, fuck those digital toys, you would be better off waiting.
 

G.Beard

New member
Can't edit my last post for some reason.

Wanted to add that you can use an old PC PSU but the thing is you will need to add extra circuitry to implement current limiting and variable voltage. see, if you are using a bench PSU to inject a voltage you really need to be able to control the current / voltage.

You can use an LM317 with a pot to control the voltage and a darlington pair in a single package to supply extra current. A simple current limiting circuit can be setup with a few basic components.
Have a Google for EEVBlog Power supply. I would not look too much at the whole series of videos because it gets a bit "bells and wistles" but the basic building blocks are what you need to know.

Back to the scope. I got my first analog scope (Phillips PM3214) from an old TV repair shop. You can get them free if you know where to go begging. If you were in the UK I would gladly send it to you.
 

Monkey Bytes

New member
Can't edit my last post for some reason.
Doesn't seem to let you edit on mobile.


Wanted to add that you can use an old PC PSU but the thing is you will need to add extra circuitry to implement current limiting and variable voltage.
Which is why I feel like if I make one myself, I'll never be able to use it on actual repair jobs. Still would be nice for playing with.

Back to the scope. I got my first analog scope (Phillips PM3214) from an old TV repair shop. You can get them free if you know where to go begging. If you were in the UK I would gladly send it to you.
I'm in Kansas in the US. There are maybe 2 TV repair shops and they're notoriously expensive. Is it super feasible to try to acquire used/broken ones off ebay and try to repair them?
 

G.Beard

New member
Is it super feasible to try to acquire used/broken ones off ebay and try to repair them?

Nope.

Look on eBay for philips pm 3214 I found one for $68 but it's not linking. Just goes to eBay with no search
Someone may have a better idea but thats what I would do to find an actually usable scope
 
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Monkey Bytes

New member
Look on eBay for philips pm 3214 I found one for $68 but it's not linking. Just goes to eBay with no search

Found one from Canada. $50+$40 shipping and claims to not be calibrated in any way.
I will keep an eye out for Analog oscilloscopes in general. I see many ranging from $50-150, and most appear to have been discarded from schools. The general trend is "As-is, powers on, not properly calibrated." Any obvious things to watch out for? As in, common ways an oscilloscope gets destroyed. I'll try to match or exceed the specs of the PM 3214 if you say it's usable.
 

G.Beard

New member
Probably will not need calibration. Just make sure you see that it has been tested and it displays a trace. Chances are you will not have to do anyhting. It's not like you'll be taking critical meassurements of anything. You just want to see a waveform right?

Another thing you might want to consider is a PC based USB scope.

Louis has a 50MHz Rigol DSO1052e scope and I think I have seen special offers on them since they have been superseded by the DSO1054z.... An entry level but kickass scope for the money. I hacked mine to 100MHz and you can find the hack all over the web. Especially on EEVBlog

If you get an old CRT and for any reason, you do need to calibrate the thing you can just download the datasheet and follow instructions. If you need to calibrate ALWAYS WORK WITH ONE HAND BEHIND YOUR BACK. I shit you not, the flyback transformers in these things put out kVs and a powered down unit will kill you just as fast if you touch a HV capacitor. Left hand in pocket or behind your back, keep shooes on, do not touch any capacitor leads.
 
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