Re: micro power square wave oscillator

On Jul 2, 1:04 pm, John Fields <jfie...@xxxxxxxxxxxxxxxxxxxxx> wrote:
On Tue, 1 Jul 2008 19:39:23 -0700 (PDT), bill.slo...@xxxxxxxx wrote:
On Jul 2, 9:40 am, bill.slo...@xxxxxxxx wrote:
On Jul 2, 1:10 am, nukeymusic <NuKeyMu...@xxxxxxxxx> wrote:

I'm looking for a schematic for a square wave oscillator which draws
around 10uA, powered by 2 to 5V and oscillates at around 100kHz with a
50% duty cycle. I tried out some schematics around a 4007 but none can
meet all the requirements.

A simple two transistor astable multivibrator should do the job.

http://www.freepatentsonline.com/3705362.pdf

You'd need low capacitance transistors, so the BFR92 and its PNP
complement, the BFT92 might be useful

http://www.nxp.com/acrobat_download/datasheets/BFT92_CNV_2.pdf

Like the BFR92, the BFT92 will need a 22R (or bigger) base stopper,
and can't take more than 2V of reverse bias across the base-emitter
junction.

---
Can you post a schematic showing something that works, or do you just
want to pretend to, as usual, know what you're talking about?

Since I'm posting via a telephone modem - my brother's house in Sydney
has every luxury except ADSL - posting a schematic would be time-
consuming. An LTSpice text file would work, but who needs it?

The patent I pointed to does include a number of schematics, and if
you need a schematic for conventional two-transistor astable
multivibrator, you can find one with google.

You don't seem to appreciate precisely how simple a two-transistor
astable actually is. I did once see someone build a two-transistor
multivibrator that blew up its base-emitter junctions, whence the
warning, but it isn't a complicated circuit.

--
Bill Sloman, Nijmegen
.