Hi list members, I've a question on what "should have been" a truly simple circuit. I'm trouble-shooting the electronic side of a gas chromatograph, all computer controlled. I've got power but the clock signal is not there. Well it's there but as a 1.3 V p-p sine wave of the correct frequency (7.09 MHz). That's not going to clock anything. I know it must be a square wave. The manufacturer is using 3/6th of a 74LS04 with the crystal across pins 1 and 4. There is a 1K resistor across pins 1 and 2 , a 91 ohm resistor between pins 2 and 3 and a 1K resistor across pins 3 and 4. There is a 56 pF cap from pin 3 to ground. Pin 4 drives another inverter, pin 5. So the output I would expect should be a square wave of about logic voltage from pin 6. But its not. Its a sine wave of about 1.4 Vp-p. I even breadboarded the circuit and I'm still getting a sine wave.
I'm quite green when it comes to crystals. So what am I doing wrong? And more importantly do you have any suggestions on how I might square up the problem. Many thanks for your time. Its greatly appreciated. Chuck Eisnor -- Charles R. Eisnor Service for Laboratory Equipment & Instrumentation http://www.scientific-electronics.com ph: 902-681-0998 fax: 902-681-1276 -- Author: Charles Eisnor INET: [EMAIL PROTECTED] Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: [EMAIL PROTECTED] (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB CHIPDIR-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).
