Hello to all, and many thanks in advance for any assistance.
I built a 45 minute timer for a friend using 4510 BCD counteers, 4511 decoders, some NOT and AND gates. To get the minutes to reset on 45, I simply send the correspong outputs to an AND gate, and it resets accordingly.
I need to add a chime to sound on the counter reset, and I was thinking that all I would need is to feed the output of the AND gate responsable for the 45 minute reset into a small signal emittor-ground amp, and get out a little tone from a small buzzer, but that really is not coming together as I would have liked!
It seems that when the AND gate sends the output signal to reset, that I get no voltage on the output pin, which is impossible since the counter does in fact reset! But my multimeter is reading a big fat 0!
What the hell is going on! The output pin of the AND gate shows a steady mV output of around 18-23mV, which does not change when the output is supposed to be high!!! But as I mentioned, something is going on because the counter resets! The output high voltage of the 4002 AND IC I am using should be around 8 volts according to the power supply voltage I am using.
I really am at a lose here. Any insight would be greatly appreciated.
I built a 45 minute timer for a friend using 4510 BCD counteers, 4511 decoders, some NOT and AND gates. To get the minutes to reset on 45, I simply send the correspong outputs to an AND gate, and it resets accordingly.
I need to add a chime to sound on the counter reset, and I was thinking that all I would need is to feed the output of the AND gate responsable for the 45 minute reset into a small signal emittor-ground amp, and get out a little tone from a small buzzer, but that really is not coming together as I would have liked!
It seems that when the AND gate sends the output signal to reset, that I get no voltage on the output pin, which is impossible since the counter does in fact reset! But my multimeter is reading a big fat 0!
What the hell is going on! The output pin of the AND gate shows a steady mV output of around 18-23mV, which does not change when the output is supposed to be high!!! But as I mentioned, something is going on because the counter resets! The output high voltage of the 4002 AND IC I am using should be around 8 volts according to the power supply voltage I am using.
I really am at a lose here. Any insight would be greatly appreciated.