In message <01bd60ae$bd691b40$c1afadce@robm>, Mitch Robbins writes >I'm looking at the potential of using a pic output, possibly PWM, to drive a >charge pump/switched capacitor circuit for generation of negative voltages. >I need approx 10mA at -15v. I'm trying to avoid that extra chip or 2. A >home brew 7660? > >I'm sure someone has been there before. Has anyone had any luck in this >area, have circuit concepts, good references, or theory. I did this many years ago with a Z8, to get a -ve supply for the RS-232 interface, which used an op-amp. Leon -- Leon Heller: leon@lfheller.demon.co.uk http://www.lfheller.demon.co.uk Amateur Radio Callsign G1HSM Tel: +44 (0) 118 947 1424 See http://www.lfheller.demon.co.uk/dds.htm for details of my AD9850 DDS system. See " "/diy_dsp.htm for a simple DIY DSP ADSP-2104 system.