You're the second one to suggest a PIC digital solution. I think it's not practical because you would have to clock the PIC at 10 Mhz (or higher) in order to get small increments at the 55 Khz output. Doesn't the clock frequency limit the smallest length of time that the PIC can be driven high? For instance, a 36 Khz clock would mean I could not run the vco at any frequency less than 36 Khz.... The application is for a piezotransformer based photomultiplier tube (cockcroft-walton) power supply, so digital jumps in the output frequency will make steps in the output of the poser supply instead of nice slow and smooth increments from an analog solution. This is probably a case where analog is better because the digital solution requires a very high clock frequency, thus more supply current is needed. Am I in error? Thanks, Art At 05:30 PM 5/2/2005, you wrote: >On May 2, 2005 02:45 pm, Peter wrote: > > On Mon, 2 May 2005, KY1K wrote: > > > Date: Mon, 02 May 2005 10:37:43 -0400 > > > From: KY1K > > > Reply-To: Microcontroller discussion list - Public. > > > To: Microcontroller discussion list - Public. > > > Subject: [OT] Micropower vco needed > > > > > > I need a low frequency vco that draws very little power. I googled > > > and found tons of uhf and higher vco's, but they all draw much more > > > power than I can supply. > > > > > > I need something that will oscillate between 55 and 65 Khz. It has > > > to draw microamps of supply current, and I prefer the control > > > voltage range to be between 1 and 3 volts. > > > > > > I'd like to have a chip solution if possible. > > > > CMOS4046 PLL (74C4046 etc) > >At micoamps worth of current, why not use a 16f5x or 12f5x running in RC >mode, then use a varactor as your C. >Something like this: > Vcc > | > Z > large R | >Cntrl Voltage>--+--WWW--+---|(--+--PIC RC > | | > large _ _varactor > cap. ^ ^ > | | > gnd gnd > > > > Peter >-- >http://www.piclist.com PIC/SX FAQ & list archive >View/change your membership options at >http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist