At 10:28 PM 7/13/02 -0400, Byron A Jeff wrote: > In fact >I just updated my LVP schematic with a circuit that I know has worked in the >past. However I caution you that IT IS UNTESTED IN ITS CURRENT FORM: > >http://www.finitesite.com/d3jsys/proghvp.gif Hi there, Byron. The circuit you posted for HV programming won't work. I assume that the 2n2222 transitor is wired as an emitter follower: C to +13V, E to MCLR. The reason it won't work is that the HCT573 has totem pole output drivers: a HI is 5V, a LO is 0V. The highest voltage you will see on the emitter of the transistor is about 4.4V, not the +13V that you want. The easiest solution is a 2 transistor switch: the HCT573 drives a NPN transistor which in turn drives a PNP transistor fed from the +13V rail. The extra cost is minimal: 1 more transistor, 2 more resistors. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 18 years of Engineering Innovation (1984 - 2002) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' 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 hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu