Fork me on GitHub

Project Notes

#635 CD4001 SR Latch

Set-Reset latch implemented with CD4001 NOR gates.

Build

Here’s a quick demo..

clip

Notes

This circuit is another implementation of a Set-Reset flip-flop, this time using NOR gates. Sometimes this is referred to as a “NOR Latch”. A CD4001 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:

KM0DdEaY5sY

Truth Table

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

Construction

bb

schematic

Build

Credits and References

About LEAP#635 Digital LogicCMOS/TTL

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

Project Source on GitHub Return to the LEAP Catalog
About LEAP

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.

Projects are often inspired by things found wild on the net, or ideas from the many great electronics podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know or send a pull-request.

NOTE: For a while I included various scale modelling projects here too, but I've now split them off into a new repository: check out LittleModelArt if you are looking for these projects.

Project Gallery view the projects as an image gallery Notebook reference materials and other notes Follow the Blog follow projects and notes as they are published in your favourite feed reader