CA3140 data sheets show that the output can approach the positive rail and (allegedly) reach the negative rail. This might be false. On a single rail supply the offset cannot be trimmed to get a true zero output, you MUST have some negative.
I want to measure up to 30 watts at 1W/V from a thermopile sensor, on a multimeter, so my idea is a split rail supply whose total is 34 volts, with
30 volts on the positive side and just a few hundred mV for negative, to
get through-zero adjustment for offset error.
Will this work without frying the IC? Can anyone suggest common, low price, good performing IC's for this? It doesn't have to be a single rail op-amp, it just has to accept a VERY asymmetrical split rail. I'm hoping the LF411 or LF412 (with external offset trim) can do this.
I can make the dual supply stage, that's not the tough bit, but I'd like some advice about the extreme asymmetry I want for the gain stage. (Both will hopefully be workable from one dual op-amp IC).
-------------------------------------------------------------------------- PS. Sorry about the repost, but I really want some help here, and my last post got entirely lost behind the mark-up debate. I've reduced this post a LOT to try to gain some attention to it. :)