Electronic latching circuit?

[bobleny]

Is there such a thing as an "electronic latching circuit"? Like what is used in motor controll where a relay will power its self once a button is pressed...

Mainy I was just wondering if that is possible, and if possible a diagrame...?

Thanks!

 

[ZomBiE]

there's tons of them, by single IC or via discrete components

 

[idevices]

Quick and dirty, you can use a 7476 (J-K Flip-Flop) in toggle mode.  Tie J and K high, a relay driver tied to Q and your switch on the clock.  You will probably need to debounce the swictch.  You can also use one switch on the preset and one on the clear to start and stop the motor...

 

[hotwaterwizard2]

An SCR works well on DC.

View attachment 39919

View attachment 39920

 

[Cabwood]

I'll suggest a simple bistable using two transistors. It'll work with any voltage up to the limit of the transistors, but only with a DC supply and load.

You could switch a relay as the load (don't forget the protective diode). The circuit shown, with two BC108 transistors, will switch up to 200mA. If you want more, you'll need to replace TR2 with a power darlington.

View attachment 39925