x0xb0x VCO Tuning help

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antto
 
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Joined: Thu Apr 15, 2010 3:21 pm

Re: x0xb0x VCO Tuning help

Post by antto »

well, i just connect the croc clips from the circuit to the audio card (on one channel)
however, have in mind that the voltages in the circuit can be higher than usual audio signal, and also contain DC
in my case, my sound card (m-audio audiophile 2496) is AC-coupled (it has high-pass filters on the input which remove the DC) and it appears to tolerate higher voltages fine (it probably has protection)

basically, use a resistor on the probe if you'll probe somewhere where there's high voltage
more resistance == safer (and quieter signal)
so always start with a very high resistor if you're not sure, and then if the signal is really quiet - use smaller resistor

now, for actually controlling the vco, i use the sequencer and play a specific pattern (two C notes one octave apart)

if you're building a x0xb0x - you don't have to calibrate the vco precisely
when i was building my x0x, i already had another one which was working, so instead of supplying 3V from a battery to the VCO - i injected the pitch CV directly from the working x0x while it was playing patterns, so i managed to tune the new x0x at that point even
but this is not important, leave the trimpots in the middle or so, and continue the building
then, once you got the sequencer working - you can use this plugin for easily tuning the vco without putting probes in the actual circuit

mattittam
 
Posts: 5
Joined: Tue Feb 18, 2014 9:16 pm

Re: x0xb0x VCO Tuning help

Post by mattittam »

thanks for your quick answer :) but i still don't get how to connect the croco clip to the sound card..i have this xlr/jack combo inputs. how do i get the signal inside? where do i have to connect the croc clips on? never did this..

and are there any values i can measure to check if i soldered the parts in correctly and no part has been fried? maybe on IC11?

thanks for helping :)

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antto
 
Posts: 1636
Joined: Thu Apr 15, 2010 3:21 pm

Re: x0xb0x VCO Tuning help

Post by antto »

oh, no idea about XLR
mine are RCA and it's simple..

with RCA i simply connect the outter side of the plug to ground, and the center thru a resistor (or pot) to the point which i want to probe

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