At 08:27 PM 8/10/2004, Josh Koffman wrote: >Second, I'm reconsidering my single rail only requirements. If I go >with an ICL7660 type inverter, Hi there, Josh. I've been following this discussion but didn't get a chance to respond 'til now. 1) pots: Digi-key part numbers P2G1103-ND POT 10K OHM 12MM VERT MET BUSHING P2T3103-ND POT 10K OHM 12MM HORZ MET BUSHING These are nice and small and are PC mount. You can cut the shafts down to whatever size you need. 2) bipolar supply: you don't really need one but it does make things easier if you have a negative rail. If you really do have to stick with a single supply rail, create an artificial ground with a voltage divider followed by a buffer. This means that all your inputs and outputs have to be capacitively coupled. While this is not a problem for the output, it *is* a problem for balanced inputs: you have to ensure that the capacitors are matched or the CMRR goes out the window at low frequencies. I've got a couple of boards that do this and it is a *pain* matching all those caps. If you don't mind my asking - why not just use 2- 9v batteries? Or, if current consumption is a problem, 2- 9V battery packs built from AA cells. The lowest noise op-amp I've used to date is the LT1028. But it's a current hog and runs warm from a bipolar 12V supply. 3) Microphone pre-amp chips: an old favorite is the ssm2017 from Analog Devices. This part was discontinued but one of the disti reps told me recently that Analog Devices was going to bring it back because of customer demand. It is available from places like America II right now but you pay a premium from those guys. However, if you need only a few, that is by far the most cost effective easy solution. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 20 years of Engineering Innovation (1984 - 2004) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.