switching relay

[nfsus]

im looking for a 12v relay that will switch between "a" or "b" with a 12v momentary switch. no constant power at the relay, only the momentary power from switch "a" or "b". it would need to switch and lock after power is removed and then switch back when polarity is reversed and lock there. i tried an automobile relay jd142c that is a latching relay but it also needs constant power. not what im after

 

[AudioShockwav]

I think you are looking for this type " latching relay"
Example:

Latching/Bistable Relay - 30 Amp, 12V | Del City

Latching/Bistable Relay - 30 Amp, 12V: Efficiently control electrical circuits with our durable latching relay, operated by two sensors for a reliable memory function. Ideal for use with our Hella connector block kit.

m.delcity.net

Maybe?

73
Jeff

 

[nfsus]

That relay will be on or off. I need on or on a or b never off

 

[Shadetree Mechanic]

Relays like that are hard to find now days. Back in the day when factory machinery was controlled by relay logic, this was a common device. But that was over 30 years ago, now days the machinery is controlled by a programable logic controller (PLC).

What devices are you going to control with this?

 

[nomadradio]

A 'double throw" relay will close one circuit when the coil is not energized. That circuit opens and another one closes when the coil is energized. Makes it an "either-or" switch function.

This can be done with a 12-Volt single-pole double-throw relay and two pushbutton switches. First, the 12 Volts connects to the relay's "common" pole, the one that selects either the NC when there's no coil current, or the NO that closes when the coil is energized.

One pushbutton type is normally open, and closes only when pressed. The other one is a normally-closed type, and only opens the circuit when you press it.

The normally-closed switch will go in line with the relay's coil.

The normally-open switch will go from 12 Volts to the hot side of the relay coil. The 12-Volts that comes out of the 'on when coil is energized" or NO (normally open) side WILL ALSO go to the hot side of the relay coil. It will hold itself in the energized condition until the normally-closed switch is pressed and cuts the coil circuit.

Can you read an electronic schematic diagram? I have discovered that not everyone does. If so, I can draw it up in that form.

And if not, I'll save myself the trouble.

But that's the plain-language version of what you described.

One output from the relay is hot when the coil is energized. The other output from the relay is hot only when the coil is NOT energized. One or the other is always on.

73

 

[nfsus]

im wanting this setup. a single pole double throw. on/on.

the 12v coil determines which terminal is connected to the common, (a or b), depending on polarity of 12v momentary switch. switch power will only be used to throw the relay and it will remain in that position even after the switch is released. no holding (latching, sealing) circuit, that would be mechanical basically

 

[vu2nan]

Hi nfsus,

An SPDT spring-return switch with centre off, a magnetic latch relay and an electrolytic capacitor would be required.

In one end position of the switch, the capacitor charge pulse will set the relay and in the other end position, the capacitor discharge pulse will reset it.

Nandu.