Are there any readily available op amps with built in resistors that give a fixed gain, say 5, 10, 50, 100 etc. A lot of times I need to boost a sensor output and I'm too lazy to find/solder resistors do it. I'd rather buy a bunch of pre-set amplifiers that are ready to be plugged in and multiply my voltage. Tried looking around on the web and couldn't locate anything. Thanks.