You can build an S/R latch using a couple of cross-coupled NOR gates (or NAND gates). But is this a combinational circuit or a sequential circuit? Or is it a bit of both? With a 74LS02 and a 74LS00 on a bit of breadboard, there's much fun to be had drawing truth tables and state diagrams.
By Julian
Youtuber, shed dweller, solar charge controller aficionado
"It acts kinda like a toggle switch"
I think Julian has kinda missed the point.
Had a good nap listening to this one – naps are important 🙂
I like your slightly out-of-the-box thinking. Though of course, if you just want a true Q/notQ output, you don't need another pair of gates. You just have to discard one of the original outputs and recreate it with a NOT gate from the other. The result of having S and R active at the same time might be different than the 4-gate version, but that's beside the point. 🙂
Hi Julian, I think you rather missed the normal function/use of an S/R latch. Using normally closed switches or another arrangement giving a 'normal state' of logic 0 inputs would make this much clearer. At the end of the day, an S/R latch has a SET and RESET input, both should 'normally' be 0. Having them both normally high breaks it, so you don't really see the expected latch function.
I love watching videos on basic stuff like this especially when it explained so calmly.
wanna show a flank triggered JK flip flop? =D
What about your optoisolator computer?
Now how do you move from the two input electronic switch to only using one push button? And then maybe enabling a power mosfet for a larger circuit?
Does that chip say Malaysia on it? 😀 I dont know why im so happy xD
one dimensional PONG 🙂
The only rule in electronics is "Don't let the smoke out."
I remember I learned basic logic gates like this thirty years ago…I seem to have forgotten how they work though, since most of my work revolves around programming virtual test equipment in LabVIEW. Thanks for the refresher course. \;~)
I always look forward to your videos.
Something is definitely wrong with your first circuit – it's clearly not a latch. Did you forget feedback? As per the name, the last button press is supposed to LATCH. The other button would then UNLATCH (swap the values of the two outputs). As shown by your second circuit. And the states are undefined and should be undefined, regardless of what you wish – given that the two inputs are specified as SET and RESET – clearly implying that only one should be on at once.