Another Simple Momentary Pushbutton Latching Circuit

[Transmogrifox]

I'm in the process of designing an HV tube pedal for my bro, and along the way wanted to come up with a way to latch channel switching relays and see if I could knock off a resistor or two from the more conventional designs.

As it turns out I came up with something that isn't earth-shattering, but it is another simple way to get the job done.  I think the layout flows a little more simply than the standard dual NPN flip-flop.

Here is the schematic:


I added a little tidbit on the side showing how it might be used to drive a latching relay.  All in all it keeps parts count lower than most options -- particularly for a non-latching relay as I intend to use in the tube pedal.

In the end I can't see that it is superior to the conventional methods, but it sure was a lot of fun to see if I could find yet another way to tip a flip flop with a momentary switch.  You'll notice the thing with the R5 and C2 it's essentially the same thing as RG Keen's CMOS flip flop. 

Anyone wanting to try something non conventional please give it a try and let me know how it works out.

[bool]

A very minor nitpick, but a useful one if you plan to "industrialize" your design. Just connect the R4 ("LED resistor") straigh to your Vcc instead to the PNP base. Should make bussing the LEDs much easier and would nil a potential error source caused with wiring errors or wear etc.

[Transmogrifox]

Thanks.  Seems a good suggestion about the LED.

[R.G.]

Nice. I like it.