Simple solution to extend this switching circuit?

Thread Starter

xox

Joined Sep 8, 2017
440
I've been toiling away on this idea for weeks now and finally got it working...for the most part. It still doesn't do exactly what I need it to do yet though and I was hoping someone here could give me a hand.

Basically it's a momentary-switch-actuated SPDT switch-actuator built from op amps. Engage the switch and OUT goes high while ~OUT goes low. Engage again and the outputs toggle.

circuit.png

What I really want is for it to essentially work like a T-flip-flop. One pulse to turn on, another to turn off (the pulse ultimately coming from an other momentary switch). Now I suppose I could just replace the existing momentary switch with a mosfet or some such, but I was hoping another op amp in the equation could do the trick (since I'm using LM324 quads anyway). Not sure how that would be done though.

Any ideas?
 

DakLak

Joined Jan 20, 2013
4
Here are a couple of circuits (An apparently unrelated link and promotional information removed by moderator)

SoftToggle1.jpg SoftToggle2.jpg

 
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Thread Starter

xox

Joined Sep 8, 2017
440
Why not use a J-K flip-flop such as CD4027 or 74HC112 with J and K inputs wired to logic-HIGH?
That would work fine I suppose, but partly there's just the curiosity of how it could be done with op amps. Other thing is I've got a whole box full of these little buggers (LM324's) which I'd like to repurpose for the task. :p
 

Thread Starter

xox

Joined Sep 8, 2017
440
How about implementing the second circuit provided by DakLak in post #3, but with and LM324? It toggles.
Well I'm looking at it, but I still can't see how that could possibly be triggered by a pulse. :confused:

Incidentally, I did sort of figure out a way to do this with a slight modification to the circuit on the breadboard. Removed C1 and sending a 2.5V pulse to the output terminal of the lower op amp (not the line marked "out" in the schematic, that is, but the proper output terminal). Anyway, it's glitchy and doesn't work at all in the simulator, so not quite sure if that's going to be a viable solution in the long run...
 

DickCappels

Joined Aug 21, 2008
6,370
If you want to make it work with an electrical signal rather than a mechanical contact closure you can use something like this.

upload_2017-12-23_11-2-54.png
The circuit in post #3 is not edge sensitive like a T flip-flop. It reads "Press on, hold off latch" but it might give you some satisfaction to get it working :)
 

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Thread Starter

xox

Joined Sep 8, 2017
440
If you want to make it work with an electrical signal rather than a mechanical contact closure you can use something like this.

View attachment 142298
The circuit in post #3 is not edge sensitive like a T flip-flop. It reads "Press on, hold off latch" but it might give you some satisfaction to get it working :)
Thanks, I'll give it a go. Cheers!
 
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