2 questions. Switch stratoblaster pot to 100k? how to turn 50kpot into 100k pot?

Started by elenore19, February 28, 2011, 07:15:18 PM

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elenore19

Would switching to a higher valued pot give me even more gain/boost out of this guy? I use it to push my ts808 and I'm wondering if I can have it be pushed even more with a simple pot upgrade...
Also is there a way to wire up some resistors on a 50k pot to make it into a 100k pot? (not sure if it matters but it's a C50k..reverse audio taper I believe is what it's called..)
Thanks for the help!

-Elliot

Mark Hammer

The answer is No.

The circuit increases gain when the resistance to ground through that 10uf cap gets smaller.  Indeed, you probably don't even anything as large as 50k.  Many other similarly-structured single JFET or single MOSFET boosters tend to use pots in the range of 5k and less.

Using a smaller-value pot will not get you any more gain, though, since max gain is achieved when the pot resistance is zero, and you can get zero ohms with a 1k pot, 10k, 100k, or even 10meg pot.

petemoore

  Can't remember the schematic kinda think that's a source AC bypass variable resistor...ie gain goes up as resistance gets nearer zero there.
 Hafta take a look to be sure though.
 50k can't = 100k
 100k is {50k x2} in that regard.
 Pots are a resistive wafer with a wiper somewhere between the two ends of the resistive strip.
 Where the wiper touches determines the division numbers.
 on a linear pot 50k 50k on each side of a 100k wafer occurs right at center setting [real close].
 move a bit to the left and the division is 40k / 60k [the 'divided wafer'..where the wiper touches still and always adds to total to the wafer resistance value.
 Turn it a bit to the right [cw] from center and a 60k / 40k [symmetric to the 'left turn' but on the other side now].
 10k / 90k ... 30.1k / 69.9k  no matter where the wiper touches between the ends of the resistive wafer strip, the wafer strip value doesn't change, only the divider values change.
 Put a voltage across the wafer and it's now a variable resistive voltage divider, and will divide voltages in the same manner it divides the wafer resistance.
 Not too much voltage over a small value [dinky bit of wafer can easily be heated if too much current goes through it, causing blue smoke to be emitted, a stop resistor [fixed resistor outside the pot] may be chosen to limit max current across a variable divider with 9vdc across it.
Convention creates following, following creates convention.