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This is a simple up and down counter.
It works as following:
The 555 timer will provide a pulse to the two and gates up top. One pf the terminals of each and gate is connected together so that the pulse from the 555 goes to both and gate. The other two terminals determine eitjer counting UP or DOWN depending on their input signal. If one of those pins get HIGH, the and gate of the specific pin will output the pulse fed in on the other input.
The state of those terminals is dependant upon the output state of the SR-Latch. When the counter outputs a binary 0 (0000), the latch will SE, enabling the and gate on the UP terminal of the counter. When the counter reaches a binary 10 (0101), the latch will reset and the inverting output of the latch will enable the DOWN terminal of the counter disabling the UP terminal. Thus the counter starts counting down and when a 0 is reaches the whole process will start over again.
The configuration with the two nor gates is the SR-Latch. The circuitry for controlling the Latch are all the gates below the counter.
Underneath the 7-seg-display there is a butten which will reset the counter when pressed.
On the oscilloscope you can see how the switching works. The steady lines represent the state of the two outputs of the SRlatch (they are always an invert of one another). You can see which terminal is high, either up or down, and you can see the corresponding pulse going into it.
Thank for your time. I hope you enjoy the circuit and learned something from this. If you have any questions feel free to ask :)
If you have any improvements, tips, additions, feedback etc. Comment them and I will take a look what I can do cuz I like to learn more stuff too! :)
Thx, bye bye...
- Kai
*btw this circuit is big and complex dor what it does but it's just for educational purposes to learm about digital electronics so please don't comment on that. Thank you in advance.*
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