Hello, thanx for picking this up.... There is an example of an op-amp voltage buffer in my Stamp programming manual. I'm wondering if I should try this one. There's a 4.7k input resistor, a .47uf cap to ground, then through a 10k resistor to the non-inverting(+) input on the single-ended supply op-amp. The feedback loop from the ouput of the op-amp to the inverting input has a parallel 0.1uf and 2k resistor. I beleive my PWM frequency is approx 3.9 kHz. I am using the PWM mode in a 16c72 with a 4mHz crystal. Will this voltage follower work just fine? I have a simple RC filter right now. I have a scope, and when I 'zoom' in on the voltage signal, I can see a sawtooth ripple. I would like to get rid of this ripple, as I am updating a Voltage to Frequency convertor. Thank you, Dave On Wed, 19 Nov 1997, Nigel Goodwin wrote: > In message , > Dave Celsnak writes > >I beleive there are many topics discussed on this list. > >(The Laser LawnBoy!?) > >Maybe someone could just offer a reference to other discussion lists. > > > >Example: I am looking for a circuit that can turn my PIC PWM output into > >a nice steady voltage (no ripple). Is there a discussion list just for > >hardware? > > If you look at the circuit of almost any non-digitally tuned TV from the > last 10-15 years (one that uses search tuning, and even some digitally > tuned ones) they use a low-pass filter to covert a PWM output to a 0-30 > volt tuning voltage. The ripple on these is extremely low - even small > amounts of ripple can be seen on the picture as the tuning varies > slightly. If you don't have access to any TV circuits E-Mail me directly > and I'll scan you a suitable example. > > -- > > Nigel. > > /--------------------------------------------------------------\ > | Nigel Goodwin | Internet : nigelg@lpilsley.demon.co.uk | > | Lower Pilsley | Web Page : http://www.lpilsley.demon.co.uk | > | Chesterfield | | > | England | | > \--------------------------------------------------------------/ >