Volume pedal idea.

[simon111]

I want to mod my 250K volume pedal with a sweepable min / max range. As I have a distortion pedal that I want to control - when viewed on pot from 9oclock to 2oclock of the range or anything between.

I understand I can add a pot below the volume pedal , ie from lug 3 of the volume pedal to lug 1 of the min pot and use the min pot as a variable resistor (lug 2&3 connected together). In testing 22K to ground seems to mirror the 9oclock setting. That works fine.

But I can't work out how to have a 'max' range. To go from 2oclock to full deflection ( ideally using another potentiometer) i.e. one for min range, one for max range.

Any help would be welcome.

Also Would introducing the min pot in this way cause any noise or loss of signal?

Simon.

[simon111]

Would adding a variable resistor inline with the volume pedal (before the volume pedal i.e. output of the circuit) do what I want it do?

[Paul Perry (Frostwave)]

Sure, put a pot (wired as a variable resistor) above and below the existing volume pot & you can control max and min.

Note though, there will be interaction between the 'max' and 'min' controllers, that is to say, move one & you have to retweak teh other. You can get tehre though with a bit of practice.
Also, the original circuit now has a volume pot that appears a higher value than before. usually his won't make a difference to the operation of the circuit, or to the tone - but it might.

[simon111]

Below is the circuit that I was messing around with last night.

It works fine, no problem at all, well except one.

When I have the Restrictor pots on some resistance, there seems to be an increase in hum when on medium to high gain settings on amp. This increases as I increase the resistance of the restirictoroc pots. The pots are in an aluminum grounded box, but there is a noticeable heightning of hum when the pedal is half %^&*ed but it's still present when it's full up and the restrictor pots are turned off their zero resistance starting position.




Any help or alternative layouts would be much appreciated.

Regards
Simon

[simon111]

Had another mess around with my project tonight.

It does hum more than I think it should.

Any info on why and how to minimise it?

[simon111]

Could it be that the pots are acting as an aerial? Although they are all grounded. Bit stumped on this one.

[simon111]

Could it be the potentiometer type? Carbon, Cerment, etc.. Would it make a difference?