latched operation

Is there way using less relays to achieve a latched output (+ or -) with a momentary input?

I've looked the relay quick reference list over but can't seem to find a schematic that doesn't require too many relays for my needs.

Thanks in advance---this is an awesome site!


J W

From latched on/off momentary w/ brake kill:

Would the diodes be of any specific value then?

Common 1N400x are fine (eg, IN4004, 1N4007 etc).


Assuming the +12V relay/power source is the same as the switch/solenoid source - or that it doesn't matter if they cross connect - the diodes aren't needed if the load can be powered thru the switch and "lower" solenoid path until the relay contacts close.

For the most part--hopefully I'm explaining this well enough--the momentary switch would only provide enough current long enough to close the relay. The load would then be powered until the next action of the momentary switch which would then remove power from the load.

So we're still on the right path correct?

No - after the first switch on, the switch has no further effect. (You asked for latching, not toggle.)

To turn it off, you can either remove the main power, or break the "feedback" link (ie, insert a NC switch).


PS - you are correct about the switch providing the load power until the contacts close ASSUMING there is no diode in the RHS feedback leg. If the switch doesn't handle the load, it will burn out if the contacts don't take over (fast enough).