At least I think that's what they're called. Say on a DOD250, the stuff from the battery + terminal to the op-amp...
two 22K resistors
a 470K resistor
and a 10uf capacitor
How urgent are these values? I mean, how much will it affect the sound? Can I just use two 10K resistors instead of the 22Ks? And how about the 470K, if I use a little more or less, what will happen?
Thanks.
-Joe Hart
You could use 10k, but the battery will drain faster. Even 22k seems low to me... but hey!? :!: :?:
You will probably get away with using something near 470k. In fact, by my way of thinking, that's already far too high... but hey!? :!: :?: It's to do with input bias current error, if you're interested to investigate it further...
If you have enough 10k's, use two to replace one 22k and you'll be pretty close to spec.
Done in depth at http://geofex.com/circuits/Biasnet.htm
you can use 10k resistors... you could even go smaller, but the battery will drain faster. If you use smaller resistors you can use a smaller cap as well, but not smaller than a 4.7uf.
The 470k isnt actually part of the divider, but a bias resistor. Im not sure what opamp you are using.... jrc5458 470k sounds good.... you may be able to get away with 1M, but there might be some added noise due to the bipolar input. If you use a TL072 or eqivelent you could use a 1M or even higher. This value will however affect the frequency response of the input cap. The bigger the resistor the more bass response. This may not be good on the input of a distortion pedal.
Brian
try a 386...I think they work great for 9v dividing...
V+ to opamp V+
Ground to opamp ground
output is 1/2v supply...ez
I think 386's only go up to 15v so watch the supply voltage doesn't somehow exceed that amount.
I just run little [loops of wire, enough to solder a wire or two to] rails of wire above the board across a couple perf holes, coming off the 386 for V+, Ground and 1/2v, so I can easily identify and connect to them.