Is there a basic IC component that can be used as a (front/rear) fader? I have components to create a circuit a specific way but i am in a little bind for a 2 channel input 4 channel output with fader control that is controlled by 1 single potentiometer. Potentiometer center being center turn one direction will decrease front and leave rear full. Other direction will decrease rear while leaving front at full. Center turned potentiometer will leave all 4 channels at full power. That is all it needs to do. Ive been searching around for something that can do that with no luck so far. I am limited to that specific potentiometer being the sole control for the task. The circuitry can be done by any means i just rather would have an IC component that wouldn't require many extra components to do this task. And this fader circuit will be placed after the pre-amp volume-tone-balance control and before the amplifiers. So its all pre-amp level. And that is also the point where the 2 channel stereo has to become 4 channel with a fader control. Everything else is accounted for. This setup also needs to be 12 volts or less since its for a vehicle car stereo application.
Everything like that seems to be digitally-controlled these days. [u]Here[/u] are some "volume control" chips, but I'm pretty sure they are all digital.
You can also get digital pots but getting low noise with digital pots can be tricky. There are [u]"up/down" digital pots[/u] that can be controlled with a pair of pushbuttons (without a microcontroller). But, you wouldn't get full-volume in the center. And, you'd need 4 "synchronized" pots so you might need chips with a reset pin or some other trick to make sure full-volume on one pair of pots is zero-volume on the other pair.
You can get voltage controlled amplifiers (VCA) but I'm not sure how easily-adaptable they are for audio.
There WAS a voltage-controlled volume & tone control chip... Ah! I found it! The LM1035 or LM1036.
I'm pretty sure they are no longer made but it looks like you can still find 'em. They are stereo so you'd need two, and you'd need and inverting op-amp buffer to get the "opposite" control voltage from the pot.
I actually had purchased a couple LM1036 chips. I actually got those for the volume tone and balance control. Wasn't sure if they could be used for the fader control as well. . Possibly a work around with the voltage control feed the volume control and from there maybe feed the fader that the center pin feeds the outer pins on that potentiometer? Or is it a little more complicated? Im sure something along that concept would work?. Although not sure how to keep one side unchanged through half of the potentiometer and fade out along the other half.
Everything on this is regulated by single potentiometers. Balance bass treble volume fader. Maybe a couple diodes in a certain order that would essentially lower the volume to front and rear LM1036s? With that potentiometer.
TDA7388 is the 4 channel amplifier chip i am planning to use. . im not sure if they still make amplifier chips that have a similar voltage regulated fader system like the chips in the radio have. I would reuse stuff from that but those chips are the main part of the problem. And it seems like DELCO radios used their own specific IC chips. And the ones in this particular stereo were only used in 3 variations of the same radio for only 1982 model year stereos. So it is also hard to find a direct replacement part.