At 07:30 AM 6/7/2006, Peter wrote: >Jinx clear.net.nz> writes: > > > http://home.clear.net.nz/pages/joecolquitt/luxeon_lamp.gif > >Also, the voltage/current metering device using Q3 and Q4 looks like >it would introduce the Vgs of the open 2N7000s in >series with the measured voltage. No ? Assuming (from the voltage divider ratios) that the voltage at AN2 is less than 3V and given that Vgs for a 2n7000 is less than 2V (1.3V for some variants), there should be no problem. This also assumes that the voltage drop across the current sense resistor is low enough that the body diode of the inactive 2n7000 does not conduct. It actually looks like a competent design. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 22 years of Engineering Innovation (1984 - 2006) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist