slippyr4 wrote: > The only thing i'm uncertain of is how long olin's circuit will take > for the waveform to stabilise once i start outputing a square wave. The circuit is just 3 simple single pole R-C filters cascaded. Worst case you could take the sum of the three series resistors times the sum of the 3 filter capacitors and get a time constant as a rough upper bound on the time frame of the "memory" in this circuit. In practise the first output cycle will be somewhat different because all the capacitors start at 1/2 the supply voltage when they would be at different phases during continuous operation. The second cycle will be a lot closer, and I doubt you'd be able to distinguish the third cycle from the remaining ones on a scope. In other words, in practise the sound will appear to start and stop instantaneously. If you keep the output in high impedence state when not producing sound, there shouldn't be a pop when the sound is started. > Anyone with more experience like to take a guess? Why not use a little logic and think about it yourself? Even better, build it and look at the output. > or is that the sort of thing that can be simulated? Obviously, since several people have already do that. ******************************************************************** Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products (978) 742-9014. Gold level PIC consultants since 2000. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist