modified 6 years ago

Latch

01:15:15

Nand latch

published 6 years ago

WikiWiggs

6 years ago

If the light is already on and When the momentary switch at top is pressed (S) then the light goes out. Shouldn't it remain on?

Bushmills

6 years ago

Were you to build this from real NANDs, you may be in for a surprise: pushing a button in your circuit results in the corresponding input to be undefined. Depending on logic family used, most real inputs would then be either high, or indeed undefined, but not low as required by this configuration. Cleanest way to make simulation match reality is: use resistors on inputs to pull them high, and (closing) buttons to pull inputs to low when pushed.

Bushmills

6 years ago

When you posted your question, I was already typing my comment and didn't see it. The above suggestion also solves that problem - which is caused by the lamp pulling one input low, but the other never does, for the reason outlined above.

WikiWiggs

6 years ago

Thanks for the feedback I'll definitely give it a go and post the results. Much appreciated!

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