> You can use a 556 or a quad opamp.
> Google works for this, really.

I'm aware of Google :-)

And the 324, which is what I'm using in my actually working circuit that I
mentioned, is a quad op amp - horrible results - but could be good enough.

As I noted, I'm aware of 555, 556 and similar. The issue is turning them
into a working solution at fair price. Linearity tends to suffer where you
are using exponential cap charge - but may be OK. Getting a full 0%-100% PWM
range is often more challenging. I can play with them myself (and yet may) -
i was interested in seeing if anyone popped up with a working superior
solution rather than just the skeleton ideas.

So far the LPC901 seems the most promising processor based solution. I like
my 4060/339 idea for a non-processor alternative 0 the digital ramp would
overcome the cheap opamp setup problems.



        Russell McMahon

--
http://www.piclist.com hint: To leave the PICList
mailto:piclist-unsubscribe-request@mitvma.mit.edu