Hi, I need to add simple amplifier to my digital system which is powered from a single 5V battery. To achieve proper operation of the operational amplifier I need at least +8V and -8V voltages. I can build a simple voltage multiplier and inverter like shown here: http://upload.wikimedia.org/wikipedia/en/thumb/b/ba/Stacked_Villard_cascade.svg/400px-Stacked_Villard_cascade.svg.png using the 6-CMOS inverter chip as an oscillator and a source of alternating voltage. However antoher idea is to use something cheap and standard like MAX232. Has anybody tried to use this chip just as a voltage converter? Unfortunately I can't find the output characteristics for V+ and V- pins. Maybe I'll need also additional voltage regulator to improve the quality of this power supply voltage (or maybe simple RC filter will be sufficient...). Has anybody tried to do it? -- TIA & Regards, WZab -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist