Increase Potentiometer Value?

[novotm]

Hi:

I need a 2M potentiometer for a pedal that I was hoping to finish this weekend.  However, I only have a 1M handy.  Is there a way to increase the value of a potentiometer?  I know how to decrease the value by adding a resistor in parallel, but wasn't sure if there was a way to increase the value.

Any help would be appreciated.

Thanks

[frequencycentral]

What's the pedal?

You could probably use a 1M resistor between the pot and its ground connection, if losing the first 50% of range isn't critical.

[petemoore]

I need a 2M potentiometer for a pedal that I was hoping to finish this weekend.  However, I only have a 1M handy.
  It probably doesn't need 2m worth of divider or variable resistance to satisfy your needs.
  Is there a way to increase the value of a potentiometer?  
  Not without altering or changing the potwafer = basically no.
  I know how to decrease the value by adding a resistor in parallel, but wasn't sure if there was a way to increase the value.
  Share the application for more info.

[novotm]

Thanks for the quick feedback.

The pedal is a FSH-1, built using the GGG layout, which specifies a 2M linear for the S/H speed.  My guess is that using a 1M would be noticable.  Any thoughts?

I did also notice that the tonepad FSH-1 uses a 1M reverse log for the S/H speed.  Does anyone know if there is a particular reason for this? 

Thanks

[frequencycentral]

My guess is that you could play about with the value of R29, say increase it to 1M2 - at the risk of losing some range.

OR

Use your 1M, leave R29 as is, but substitute the timing cap, C10, for a different, slightly higher value. Why not use a socket and play about until you get a useful range of speed.

Edit: I was looking at this schemo: http://www.freeinfosociety.com/electronics/schemview.php?id=1125

[darron]

if you pulled the pot apart and very gently sanded back the carbon taper evenly and measured with your DMM as you did it, you could get it up to 2M


then again, i'd just go out and buy one.

[rhys]

that pot really does just control the speed, so you could use the 1M and see whether the speed way too slow for you.  i'd probably  do what frequencycentral said and add a resistor to cut off some of the low speed and get some additional higher speeds.  with my fsh the low speed is REALLY slow (maybe 60 bpm) and i've never found a use for that. 

[GREEN FUZ]

Yeah, I would just put in the 1M in for now and replace it at a later date, if needs be.

[RickL]

If the pot is used as a variable resistor, as most speed pots are, you can add a 1M resistor in series with the pot and short the resistor with a spst switch. With the resistor shorted the total resistance varies from 0 to 1M, with the switch open from 1M to 2M. Label the switch 'Range'.