Latch Circuit

Looks great between 100 to 10ms

Nice! I see a few areas for improvement though, just take note and see if you can come up with a solution without drastically increasing complexity… 1.) Make the input more versatile, right now it can only be triggered with a push button. 2.) Remove the dependency of pulsing the input just right for it to toggle properly, (Currently, it won’t toggle when you hold down the push button). 3.) If you still need to use a passive time delay, try using a pulsed high pass version instead of low pass, it should yield much faster response times and get rid of the hold-press duration problem.

Ya, I kinda just slapped it together without messing around too much with it. Thanks for the input guys. I just needed to tweak a few items. I needed to adjust a resistor feeding the bottom NPN and make the PNP into common emmitter. It seems to work rather well now. But could you give me an example of the "high pass" method you were referring to (Issacsutt)? Also, what do you mean "more versatile"?

I just noticed you’ve already fixed the hold duration problem, nice! For the High Pass filter approach I refer to, ill give you a little example circuit comparing it side-by-side to your low pass version, it’ll be easier to visualize what I mean for this… http://everycircuit.com/circuit/5782992894820352 So, as for “more versatile”, I say that because in your circuit the input is a push button between two specific points, where neither are directly tied to high or low. Because of this, you can only trigger that input with a physical switch, and wouldn’t be able to feed the input from, say, another T flip flop or a clock for example. To resolve this without changing the whole design, you would likely need a way to replace the push button with either a transistor or two (so you can instead feed a high/low signal into the base, so the collector + emitter can do what the push button does, but digitally, or you might be able to replace the push button with a resistor and/or diode to simply tap into it with an external high/low interrupt signal to achieve the same thing in a simpler way, if it’s possible (I’m not certain that it is though, was just a quick thought).

You’d probably have to get a little creative with it to replace your low pass with a high pass on this circuit, but better yet is to use conditional logic to automatically handle the timing for you, (its usually the approach I almost always strive for in a toggle flip flop), and it would adapt to the input, so it would be even more flexible and forgiving because the timing depends specifically upon the conditions, not the input.

Ahh! Now I see what you mean by 'high pass', 'low pass'. Why did I not recognise the phrasing? Lol. Filters, got it! I see what you mean now. Ok, I will definitely have to incorporate the high pass version. Thanks for the follow up!