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bistable relay


Active Member
Do not know of such expert; but can what you say be replaced with 'latching relay' wording ?


Well-Known Member
Most Helpful Member
There are many experienced persons on this forum. What are your specific questions?



the application is this:

the objects I am referring to are electromechanical relays (not to be confused with step-by-step relays) which keep the last position of the contact in memory even when the power supply is disconnected.
they can have a single coil or 2 coils with 4 terminals or 2 coils with 3 terminals. it is useless to let the current flow continuously in the coil, a pulse is enough, I think I use a capacitor.
the questions are as follows:
it is clear to me how the single coil version and the 2 coil version with 4 terminals works. it is not the same for those with 2 coils with 3 terminals. I do not understand if it is 2 separate coils with 2 terminals joined together or if it is a single support on which 2 coils are wound with a central socket such as transformers.
I would like to know how many ways there are to control all these versions described above in order to choose the one that best suits me. I have only one port available (it can appear as a high state or a low state) to drive the relay, which is why I have already discarded the H bridges.
to drive the single coil relay I have thought of a solution that I like. use a dual power supply -6 + 6 and a darlington pair (with internal diodes to discharge the overvoltage created by the coil) complementary push pull by placing the capacitor on the base of the transistor, or a sziklai pair, but it seems that there are no integrated.
tell me how you can drive the coils of the other 2 relay versions consisting of 2 coils.
last question: the only difference I know about the three relay versions is the number of coils and their configuration. do you know other differences?
finally a consideration, it would be convenient for me to find bistable signal relays with four contacts but I don't think they exist


Active Member
There is several latching relay types with single or dual coils or number of terminals. Polarity reversal or not. Each has its method of energizing / change of state.
Do your search with the term 'latching relay' to find all about them.

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