0

VCO doesn't generate any sound
Moderators: altitude, adafruit_support_bill, adafruit, phono, hamburgers

Please be positive and constructive with your questions and comments.

VCO doesn't generate any sound

by Faye_108 on Wed Oct 30, 2019 11:05 am

I recently began building the x0xb0x. The PCB is from adafruits and the parts are from qjworkshop (ebay).
I followed the official ladyada guide closely:
http://ladyada.net/make/x0xb0x/fab/vco.html
The VCO is now half-finished. I made all the voltage tests that are suggested in the guide up to the point where the usage of an oscilloscope is recommended for the first time to test the sawtooth wave. Every voltage I measured until now was pretty much spot-on with the target voltages of the official guide, except the DC Bias between R81 and R105, which is 8.25V instead of the targeted 8.5V, but I think that is still within the accepted range, right?

As for the sawtooth wave:
Unfortunately I can't test it on my PC soundscope, since the DIY scope probe (which I made by closely following ladyada's instructions) is recognized as a headphone instead of a microphone (I have a combo jack only). From what I found out, that seems to be a common issue with the Realtek driver of my laptop.
So instead I opted for the listening method with a headphone. Unfortunately I get zero sound....like nothing at all.
Do you have any suggestions how I could locate the source of the problem?
I already double check for any solder bridges, correct polarity of all capacitors, resistance of resistors etc.

Thanks for your help!!

Faye_108
 
Posts: 4
Joined: Wed Oct 30, 2019 11:02 am

Re: VCO doesn't generate any sound

by mikeysklar on Wed Oct 30, 2019 1:29 pm

Hello Faye_108,

Have you already come across this thread which discusses troubleshooting a VCO that is not outputting?

viewtopic.php?f=12&t=39292&p=195185&hilit=vco+zero+sound#p195185

mikeysklar
 
Posts: 4513
Joined: Mon Aug 01, 2016 8:10 pm

Re: VCO doesn't generate any sound

by Faye_108 on Fri Nov 01, 2019 8:21 am

Thanks for your reply, mikeysklar. Yes, I had already found that thread. Unfortunately I couldn't derive anything useful from it for my specific case, especially because the thread opener's x0xb0x is already finished and I just began building mine.
Anyway, meanwhile I managed to test it with another laptop and the signal was showing up there. Yay!
As to why I couldn't hear anything with the headphone method, I have no clue.

Faye_108
 
Posts: 4
Joined: Wed Oct 30, 2019 11:02 am

Please be positive and constructive with your questions and comments.