trimpot vs. resistor?

[markr04]

Is there an advantage to using a trimpot if I can use a resistor to set the bias correctly? I'm building a couple pedals for friends and they will most likely use different 9v supplies than I'm using, or might use batteries. Is the resistance to achieve the voltage needed for correct bias likely to change enough to require trimpots?

Thanks for your help.

Mark

[RandomRedLetters]

well if they're still using 9v, no matter where it comes from you dont need to change biasing resistors. Now if you have a transistor socket, and changed out Si and Ge transistors, then it'd be wise to use trim pots to rebias for the new transistor.

[petemoore]

Alot depends on the rest of the circuit and transistor data.
 A pot lets you adjust the resistance a resistor is a fixed value.
 Transistors have a wide variance in the way their bias's are set from one circuit to the next.

[markr04]

Thanks guys. Yeah, I would check each board and use resistors that drop the voltage enough on that particular board. Just concerned about a different supply varying in voltage.

[RandomRedLetters]

Thanks guys. Yeah, I would check each board and use resistors that drop the voltage enough on that particular board. Just concerned about a different supply varying in voltage.

If you're that concerned about voltage fluctuating that much, couldnt you just use a zenner diode right after each +9v input on the circuit?

[optimus_prime_1985]

Ed Rembold of Tone Czar uses resistors instead of trim pots in his echoczar pedal. He doesn't any trimpots through the whole thing.