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soffiuson
Joined: Apr 15, 2016 Posts: 2 Location: Reykjavik
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Posted: Tue Oct 29, 2019 8:20 am Post subject:
VCO frequency pot size Subject description: Does the size matter? |
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Hi.
I have built two VCO's that are both working fine. I broke one of the frequency pots on the second oscillator while forcefully tightening it to the front panel Unfortunately I don't have another 22k pot to replace it. I have a bag full of 100k pots so I was thinking... Are these pots not basically voltage dividers? What would be the effect of replacing them with 100k pots? I have already replaced them and the oscillator works although I have not calibrated the cv tracking. Is there a reason not to do this?
Regards
Kolbeinn |
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Tue Oct 29, 2019 8:59 am Post subject:
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I see you're new here - Welcome!
Without a schematic it's hard to say. Not all variable resistors are used as voltage dividers. And some that are used that way are also used as a load resistor for a transistor amplifier. Still others are used as variable resistors. So while in some circuits the value matters greatly (load resistor) and others it doesn't matter much. In some circuits, a higher value may result in increased noise.
We can help much more if you post a schematic of your VCO. _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
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soffiuson
Joined: Apr 15, 2016 Posts: 2 Location: Reykjavik
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Tue Oct 29, 2019 9:57 am Post subject:
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The website calls the pots P1 through P6, but they aren't shown on the schematic.
EDIT: I see the wiring diagram now and yes, it's a voltage divider.
I'd test-replace it with the 100K pot and see if the VCO performs as it should. If it works, I'd leave it.
Worst case: might be a bit of noise going into the frequency control circuit.
Best case: it could just work as spec'd. _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
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gabbagabi
Joined: Nov 29, 2008 Posts: 651 Location: Berlin by n8
Audio files: 23
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Posted: Tue Oct 29, 2019 10:17 am Post subject:
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i would say for the fine tune pot it does not matter much,
cos it is connected to a 3,3M resistor
the 100k will behave bit different from the 22k,
but at least there is no risk in using 100k instead |
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