Flip flop or bistable multivibrator 1

[JonnyMX]

I have a system that requires a positive and negative air flow that I'd like to control with a flip flop. Meaning that one state (say the vac or negative air flow) would remain on until switched to a positive air flow, which would remain positive until the next switch and so on.

I'd like to find an 'off the shelf' version that has a relay built in, so that I can use it run a solenoid valve.

Any ideas, sources, or maybe I'm looking at the system wrong. If there is an easier way, let me know.

 

[BrianG]

For this kind of operation relay "logic" is probably the simplest solution. Ordinary relays can be made into a bistable or "latch" by cross-coupling a spare pair of contacts on the relay to keep the coil energised once the "trigger" (e.g. from a push-switch) ceases. To make things "toggle" alternately you need at least two relays in a cross coupled configuration to break the hold-in contact of the first relay at the next push of the switch. (Sorry it's difficult to describe and this site does not make attaching circuits possible)

However, when you say ".... which would remain positive until the next switch and so on" do you mean that the last setting must be remembered between successive operations of the system without any electrical power applied?

If so, one suggestion would be using a single magnetic latching relay. These usually have two coils (or sometimes just one coil where you have to reverse the polarity) and can be switched like a bistable by applying a short d.c pulse to one coil or the other. One coil flips the external circuit contacts one way, then applying a pulse to the other coil when required flips the contacts back the other way. In both cases the contacts are held in the last state without consuming any power by small magnets within the relay's construction - quite neat really.

 

[JonnyMX]

Thank you, no there is no need to remember the last position. Just that when switched/activated, the result is fliping to the other state. I'll look into single magnetic latching relay, it sounds like what I'd need.

Thanks again