Hi Martin, As I see the problem, you can not solve it in your way. What you are doing can be compared with an inverter the output of which is fed back to the input. Look at D. D is a constituent of the Reset signal and just this Reset signal has to reset D by voltage levels (no edge triggering). This will result in the voltage of D to hang somewhere between the logic levels.
The 7493 does not give you much room for playing the game. An option would be to use an extra one-shot which is triggered by the condition you need. The output of the oneshot will deliver a pulse which can be designed long enough to reset the counter. A tric, which I don't like, is to charge a capacitor on your condition via a diode and use the capacitors voltage as the input of a CMOS gate the output of which delivers the reset signal. This way of designing however frustrates the design principles of the logic family with the consequence that you can not rely on the build in noise levels. Regards, Harry > What I have is a 7493 configured to reset when the count > reaches 12 or when outputs D and C go high. At other times, I want > the 7493 to reset when the count reaches 10 or when outputs D and B go > high. For that, I can directly connect D to one reset and the other > reset could go to a double-pole, single-throw switch with the other > two terminals of the switch going to B and C. I wanted the switch, > however, to be made of digital logic so I only need ground a line to > change from B--Reset to C--reset. > -- > Author: Martin McCormick > 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). > -- Author: H.C. Croon 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).
