You don't yet pay attention to the fact that IC3 is a schmitt-trigger gate, which is required to generate proper pulses. Using simple transistor circuits without internal positive feedback may result in malfunction.
Yes I noticed that but I thought it would not be that important in this application. With a single transistor inverter I have managed to make it count but what happens is that the display is updated as the counter counts. Then it stops and shows the right frequency. This cycle repeats after 2 seconds.
The difference from the chip is that with the chip, the count process is not displayed and the count value is kept on screen until it is updated.
But I am pretty sure it can be done with discrete components, it does not seem that difficult in theory.....
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Hm... I see from the waveforms in the article that the gates outputs are not pulsed but they are square, whilst they are driven by pulses. Am I right?
By pulses, I mean the capacitor output spikes.
Then maybe this discrete monostable multivibrator trigered by pulses is the answer
https://www.electronics-tutorials.ws/waveforms/monostable.html
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But in the case of the IC, how is the output pulse time determined?
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Hm... now that I am thinking of it, there is no timing in the case of the IC. It is the schmitt-trigger that takes care of the output pulse widths.
I wonder if a TTL levels-compatible schmitt-trigger can be made