The sample rate is not critical. One typical digital sample and hold circuit uses A/D-D/A with no other parts except for maybe an inverter. That's two relatively expensive and/or hard to find parts. The other common way is to send a free running clock into a counter ramping a D/A up/down until it satisfies an analog comparitor then stopping the clock.What's the sample rate requirement? If it's low (maybe 1000 samples/sec or less), just hook up a 12 bit ADC and a 12 bit DAC to the Picaxe. Read the voltage with the ADC, and send the same code to the DAC. Microchip has some suitable chips for that (connect through SPI).
I forget Looks like I wanted to output to one of two different PWM pins depending on state of a digital input. These are just left over testing routines just to learn about A/D and PWM resolution and accuracy when I first obtained my PicAxe 28X. I was and still very impressed with the capabilities and ease of use of the Picaxe system.BeanieBots: There's some industrial servo displays - basically a pot with gear motor attached the motor turns a very large pointer (based on a 0-1V signal into an analog amp) that can be seen across 200 feet or more. We are looking for a way to return the displays to the starting points (or other significant step in the process) for each or all displays (while the actual monitored signals are still doing their thing - a visual aid so the op doesn't have to copy down numbers and try to keep a picture in his head of were everything was when the reaction began - or walk back to the control room to see the graphs)
So the sample acquire time isn't critical at all - lots of time to capture the reading, and it wouldn't change often.
retrolefty: What is button 0,0,0,0,b2,0,cont for?