On 9/27/06, Roy wrote: > I have already said I will probably adopt the idea of using low voltage > AC source for debugging - this alone may be enough. You don't need anything else than isolate the main phase from your target design, in any other easiest way than this stupid (and unuseless) bidirectional optocoupler. (think before answer right here). > > On reason is from a past experience were I accidentally put a TRAIC in > the wrong way around and the 5v supply that was direct of the phase > suddenly presented 230v AC to my PIC when the TRIAC burnt out (I was > using a PIC at the time), this failed then my programmer died and > finally my RS232 interface on my computer died also. Well if you did that, the optoisolated ICD will not help you now... :) A triac must be driven using a photo triac optocoupler (like some MOC series) if you still need RS232 to be connected to your system. Just because the RS232 ground is connected to the earth ground via PC supply cable. Just for info, I've made some PIC flame supervisors where the PIC was floated at 200DC from the earth ground. I didn't use any optoisolated WISP, or ICD or other programmers and never ever killed any PIC. And BTW, WISP is the last device which need optoisolator when is connected to a laptop *which run powered only from own batteries* . > > I was using a 1:1 isolating transformer in this case but phase to > neutral still present 230v when things Mr Murphy calls in to take a > look. :-( There is no phase and no neutral after a 1:1 transformer Roy... just one floated voltage isolated from the earth ground. Think a little deeper and analyze all options where the parasytical currents may flow in such design. Then you'll understand (hopefully) hat did I mean. Vasile -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist