What would this kind of device be called

So I'm sure here's already something that performs this function, I just don't know what it's called.

I'm thinking of an on/off switch, that takes an electronic signal to switch. But it uses power only to change the state of the switch, with no power needed to hold either position. So it's not a relay. Unless that's what those solid state ones do.

If I were to make such a device, maybe a relay with 2 coils on either side of a free floaty switch lever with detents, or maybe a clicky rotaty wheel thing that advances a bit each activation.

What's out there and what are they called?

Look up "latching relay"

Without specifying the load current range of the device it is impossible go narrow it down to a paticular device. I agree that it sounds like a latching relay but they come in all sizes. What are you trying to switch ?

The OP described a latching relay and a step or stepping relay.

Some stepping relays have a single coil and have a continuous rotation of some number of steps. Some stepping relays have two coils, one to move forward step by step for some number of steps, the other to reset to the first step.

Latching relay looks to be the ticket, thanks.

So, anyone have any known 5v latching relay modules? I'm having a hard time finding these things. Some listings use the word but the relay unit part number is the same as the rest that don't claim latching.

Google 'latching relay' and you'll find plenty of choice.

regards

Allan

Oh gosh, Google! How could I possibly never have thought to look at such an obscure source. :sweat_smile:

No, really. The ones you think I failed to find are standard relays (one coil, constant power needed to switch, passive sprung to return when no power) and the "latching" part is just chip controlled behavior. They ACT like a latching relay, but suck power to keep that electromagnet going to hold one position.

I'm not looking for a faux-latching relay module, looking for a legit latching/impulse relay that only draws power when changing states.

http://www.digikey.com/product-search/en/relays/signal-relays-up-to-2-amps/1049448?k=latching+relay&k=&pkeyword=latching+relay&pv72=1&FV=fff40010%2Cfff80368%2Ca8c0003%2Ca8c0004&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

270 of them here, that should be a good start. They aren't "modules" in the normal sense of the word though.

I've used these many times over the years, they are as common as dirt.

Note there are two types of latching relay, single coil where pulse is for on and a second is for off and twin coils where pulse one coil for on and the other for off. These might sound similar but a double pulse on the on coil will still leave it on with a double coil relay.

Here are some more choices Latching Relay 5V coil

I’m not looking for a faux-latching relay module, looking for a legit latching/impulse relay that only draws power when changing states.

As a module, here’s some with 5V coil and DPDT contacts … Single, Dual, Quad

Note: I recommend applying a 50-100ms pulse to set or reset the contacts. Do not use continuous voltage as the seller suggests.

Here’s the specification: Min./Max. energization duration 30ms/1min at <10% duty factor

Also, 12V and 24V coil versions can be found.

Graynomad:
http://www.digikey.com/product-search/en/relays/signal-relays-up-to-2-amps/1049448?k=latching+relay&k=&pkeyword=latching+relay&pv72=1&FV=fff40010%2Cfff80368%2Ca8c0003%2Ca8c0004&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

270 of them here, that should be a good start. They aren’t “modules” in the normal sense of the word though.

I’ve used these many times over the years, they are as common as dirt.

Thanks for the info.
I’ve only had experience with relays on boards that have smd components already. Not too many components, but got any advice for wiring up bare relays like that? I see resistors, capacitors, rectifier, transistor, led.
I’d like to find preassembled boards as they’d just be that much more compact than assembling my own mess of through hole components, not to mention the mad markup I’d pay to buy just a few of each.

http://www.goldmine-elec-products.com/prodinfo.asp?number=G21250 ?

Can someone explain to me the difference between coil voltage and turn on voltage?

http://www.digikey.com/product-detail/en/panasonic-electric-works/DK1A-L2-5V-F/255-2054-ND/1242202

Says coil voltage is 5VDC, but "turn on coil voltage (MAX)" is 3.5VDC. How is it rated 5V with some kind of 3.5VDC "MAX"?

Says coil current is 40mA and operate time is 10ms.

It is a dual coil latching relay. It sounds like I only need to use 40mA of 5 or 3.5 volts for 10ms to switch its state. That's probably wrong, because it sounds like I can just run an Arduino pin to it and write high for 10ms and be done with it, and that just sounds too easy to be the case.

Can someone explain to me the difference between coil voltage and turn on voltage?

Turn on is where the contacts will make, but they make slowly. This could cause arcing on the contacts for heavy current and damage them.

The coil voltage is the recommended voltage to ensure fast turn on without over heating the coils.

I emphasized the MAX because my interpretation along those lines would seem to suggest that's the MIN to activate.

Maybe it's about perspective? Maybe in some weird way they mean "3.5V is approx the MAXIMUM voltage that you can pass through the coil without doing anything to the armature"? Sounds too convoluted to be the case.

40mA is the max output an arduino can supply -- and I'm not sure what the saturation drop of the output device is....

But to limit the voltage to 3.5, you need to add a resistor of R = (5-3.5)/0.04 == say about 33 ohms in series with the coils.

And don't forget the flyback diode!

probably work OK anyway with a 10mS pulse with no problems...

regards

Allan

Maybe it's about perspective? Maybe in some weird way they mean "3.5V is approx the MAXIMUM voltage that you can pass through the coil without doing anything to the armature"?

I think you are not understanding what you are seeing here. This is not a product specification for that device, it is something to tick if you want to search for a component with that parameter.

That's not it, those are product parameters. Previous page: http://www.digikey.com/product-search/en/relays/power-relays-over-2-amps/1049447?k=&pkeyword=&pv675=4&pv72=1&FV=fff40010%2Cfff80367&mnonly=0&newproducts=0&ColumnSort=0&page=1&quantity=0&ptm=0&fid=0&pageSize=25

All of them have a "Coil Voltage" figure higher than a "Turn On Voltage (MAX)" :confused: