Another easy logic probe is the 555 timer IC, believe it or not ;) 2 x LED's, 2 x 470ohm resistor, 1 x 555 Tie pins 6&2 together and run them to the input. Put the 2 resistors in series, with an LED at either end. Tie pin 3 to the midpoint of the 2 resistors, tie the high side LED anode to +5V, and the low side cathode to 0V. Finally, tie pins 8 and 4 high and pin 1 low, and you're off to the races. I've also seen 2 parallel diodes (opposite polarities) put in series with pin 3, but I think that's an optional addon. If they're power diodes, that could add a bit of pulse lengthening. If you try this system, and decide to use a dual 555 chip (forget the number) you could add that pulse lenghtening fairly easily. --Brendan ----- Original Message ----- From: "Dale Botkin" To: Sent: Tuesday, July 09, 2002 8:47 AM Subject: Re: [PIC] Check my checklist? :) > I always just used two gates of a 74LS04, two LEDs and two resistors. In > fact, I have been known to build a logic probe into a project with a pin > to hook up a piece of wire for probing... it doesn't get much simpler. > True, it lacks fancy pulse stretching and such... suppose one could use a > 74LS123 or a 556 or something if it were s big deal. > > Dale > -- > "Curiosity is the very basis of education and if you tell me that > curiosity killed the cat, I say only the cat died nobly." > - Arnold Edinborough > > > On Tue, 9 Jul 2002, Bill & Pookie wrote: > > > IS this a job for a pic device or what? It could > > also be a pulser? Hummmm.... > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body