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Project Notes

#077 SRLatchWithNorGates

Set-Reset latch implemented with NOR gates.


This circuit is another implementation of a Set-Reset flip-flip, this time using NOR gates. Sometimes this is referred to as a “NOR Latch”. A 74LS02 is used to provide the two NOR gates required.

See the LEAP#061 SRLatch circuit for an implementation using BJTs.

Ben Eater has a great video explaining SR latch behaviour:


Truth Table

Set(t) Reset(t) Output Q(t+1)
0 0 no change
0 1 0
1 0 1
1 1 invalid state


The Breadboard

The Schematic

The Build

Credits and References

About LEAP#77 Logic GatesCMOS/TTL
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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is my personal collection of electronics projects, usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting (IMHO!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.