Trying to find a DPDT relay with "centre off" function, ie non latching

[jfm]

Does anyone know a great source for unusual relays please? I'm trying to find a relay with these functions:

Double pole double throw (aka DPDT or 2PDT)
Non latching, and centre off
Double coil
Coils rated @ 24v, though I could live with 12v coils or some other voltage

Here's a schematic. In the rest state ie with neither coil energised, A is centred and connected to NEITHER B nor C. Energise Coil 1, and A-B are connected. Energise coil 2, and A-C are connected. (BTW, my schematic shows single pole but I actually want a double pole)

I've looked thru all the usual catalogues (Farnell, RS, Maplin, etc) but can't find one. As you may know, the usual catalogue relays are single coil where you energise the coil to connect A-C and when you de-energise the coil it springs back to connect A-B. Or you see plenty of double coil latching where you energise coil 1 momentarily to connect A-B which then latch, and you energise coil 2 to connect A-C which then also latch.

Does anyone happen to know of a source for the relay I want?

BTW, I want this for the 24v linear actuator that will angle the TV in Match2's master cabin. I can easily buy a 2-button RF remote (from Nice SpA most likely; they do nice ones) with 2 voltage-free contacts that will energise either coil 1 or 2, and the DPDT switching in the relay can be used to connect a 24v DC feed to the linear actuator in either forward or reverse polarity, thus moving the TV in or out. But I want the TV to stop moving when the operator takes his finger off the button on the remote, hence I need a relay that disconnects A from both B and C when neither coil is energised. Thanks for any pointers here.

EDIT - I think this is the way to draw it in double pole configuration...

 

[Davegriff]

You could use two seperate relays, perhaps. Don't know if there'd be any 'cross-over' problems though.

 

[aquapower]

Does anyone know a great source for unusual relays please? I'm trying to find a relay with these functions:

Double pole double throw (aka DPDT or 2PDT)
Non latching, and centre off
Double coil
Coils rated @ 24v, though I could live with 12v coils or some other voltage

Here's a schematic. In the rest state ie with neither coil energised, A is centred and connected to NEITHER B nor C. Energise Coil 1, and A-B are connected. Energise coil 2, and A-C are connected. (BTW, my schematic shows single pole but I actually want a double pole)

I've looked thru all the usual catalogues (Farnell, RS, Maplin, etc) but can't find one. As you may know, the usual catalogue relays are single coil where you energise the coil to connect A-C and when you de-energise the coil it springs back to connect A-B. Or you see plenty of double coil latching where you energise coil 1 momentarily to connect A-B which then latch, and you energise coil 2 to connect A-C which then also latch.

Does anyone happen to know of a source for the relay I want?

BTW, I want this for the 24v linear actuator that will angle the TV in Match2's master cabin. I can easily buy a 2-button RF remote (from Nice SpA most likely; they do nice ones) with 2 voltage-free contacts that will energise either coil 1 or 2, and the DPDT switching in the relay can be used to connect a 24v DC feed to the linear actuator in either forward or reverse polarity, thus moving the TV in or out. But I want the TV to stop moving when the operator takes his finger off the button on the remote, hence I need a relay that disconnects A from both B and C when neither coil is energised. Thanks for any pointers here.

EDIT - I think this is the way to draw it in double pole configuration...

Would you achieve this with 2 separate relays with one side of both linked?
Or a good electronics engineer could make up something to suit

 

[jfm]

You could use two seperate relays, perhaps. Don't know if there'd be any 'cross-over' problems though.

Thanks, and yes, but I'm using the relay to reverse a 24v DC polarity so if one relay failed and t'other operated, I'd get a short. At least I think I would - I haven't thought that through very well. Can you see how to do it and post a sketch? If I use 2 relays the thing has to cope with a failure of one relay

Just to be clear on how I'm using it to reverse the polarity of the DC power to the linear actuator motor, it's this simple boy scouts circuit:

 

[aquapower]

Thanks, and yes, but I'm using the relay to reverse a 24v DC polarity so if one relay failed and t'other operated, I'd get a short. At least I think I would - I haven't thought that through very well. Can you see how to do it and post a sketch? If I use 2 relays the thing has to cope with a failure of one relay

Just to be clear on how I'm using it to reverse the polarity of the DC power to the linear actuator motor, it's this simple boy scouts circuit:

I have done the same with thrusters when modifying remotes to work I use a double pole relay and feed one relay through the other so that both wont energise together, its difficult to explain from memory but have a diagram in the office so can post if required.

 

[nigelmercier]

Lots on info via Google: "wire two relays to reverse polarity"

This is quite clear:

http://www.homebuiltrovs.com/howtorelays.html

 

[jfm]

Lots on info via Google: "wire two relays to reverse polarity"

This is quite clear:

http://www.homebuiltrovs.com/howtorelays.html

Thanks Nigel. That's perfect. Job done. I think my googling efforts were misdirected towards find a single raly, rahter than finding a combo of two, doh! Thanks again

 

[sarabande]

jfm stumped for one hour and one minute !

That must be some sort of record...

 

[burgundyben]

Surely it would be much easier to achieve this using some nice brass blocks from Nauticalia and coir rope in a loop around the cabin?

 

[Davegriff]

And if you're still worried by the possibilty that the relays sticking and causing a short, add a couple of diodes.

 

[ianj99]

I have done the same with thrusters when modifying remotes to work I use a double pole relay and feed one relay through the other so that both wont energise together, its difficult to explain from memory but have a diagram in the office so can post if required.

Yes, use 2 relays: one relay turns the power on and the other relay controls the direction. Its a method I was going to use to drive my AP hydraulic pump from a Tillerpilot which couldn't drive it directly.

 

[nimbusgb]

Buy a proper 'reversing relay'.

Here's a version with diagram http://www.texasindustrialelectric.com/relays_T24450_24.asp

Phoenix contact does a lower power din rail mounted version http://eshop.phoenixcontact.co.uk/phoenix/pdf.do?general=rsgb&UID=2980555

Go to farnel or rs and search on motor or load reversing relay, lots there

 

[superheat6k]

I would use two DPDT relays, with power to each coil A1 going via the second Com / NC contact set on the other. The first Com / NO will provide the direct function switching require.

This simple cross over would prevent either relay closing whilst the other is energised. This would easily provide the control required and would be cheap as chips for a 24vdc coil on a standard relay base. Possibly get them at Maplins, definitely at RS.

 

[aquapower]

I would use two DPDT relays, with power to each coil A1 going via the second Com / NC contact set on the other. The first Com / NO will provide the direct function switching require.

This simple cross over would prevent either relay closing whilst the other is energised. This would easily provide the control required and would be cheap as chips for a 24vdc coil on a standard relay base. Possibly get them at Maplins, definitely at RS.

That's exactly how I connect them when controlling thrusters using remotes, I usually get relays from RS

 

[mouthpear]

And if you're still worried by the possibilty that the relays sticking and causing a short, add a couple of diodes.

How and where would you put them?

 

[mouthpear]

Does anyone know a great source for unusual relays please? I'm trying to find a relay with these functions:

Double pole double throw (aka DPDT or 2PDT)
Non latching, and centre off
Double coil
Coils rated @ 24v, though I could live with 12v coils or some other voltage

Here's a schematic. In the rest state ie with neither coil energised, A is centred and connected to NEITHER B nor C. Energise Coil 1, and A-B are connected. Energise coil 2, and A-C are connected. (BTW, my schematic shows single pole but I actually want a double pole)

I've looked thru all the usual catalogues (Farnell, RS, Maplin, etc) but can't find one. As you may know, the usual catalogue relays are single coil where you energise the coil to connect A-C and when you de-energise the coil it springs back to connect A-B. Or you see plenty of double coil latching where you energise coil 1 momentarily to connect A-B which then latch, and you energise coil 2 to connect A-C which then also latch.

Does anyone happen to know of a source for the relay I want?

BTW, I want this for the 24v linear actuator that will angle the TV in Match2's master cabin. I can easily buy a 2-button RF remote (from Nice SpA most likely; they do nice ones) with 2 voltage-free contacts that will energise either coil 1 or 2, and the DPDT switching in the relay can be used to connect a 24v DC feed to the linear actuator in either forward or reverse polarity, thus moving the TV in or out. But I want the TV to stop moving when the operator takes his finger off the button on the remote, hence I need a relay that disconnects A from both B and C when neither coil is energised. Thanks for any pointers here.

EDIT - I think this is the way to draw it in double pole configuration...

WOW this post is old but the solution is even older. You don't need two DPDT relays. Doing it that way is so overly convoluted. ALL you needed was two SPDT relays. This is the same way people have been using relays to reverse polarity ever since relays and DC motors have existed. Just look up Power windows and lock diagrams. Or if you want one without looking I made a few.

 

[jfm]

Wow this thread is very old. Back in 2013, I wired it as per Nigel's post #6, cost about £5, took 15 mins, and it is working/has worked perfectly, ever since.

 

[mouthpear]

Wow this thread is very old. Back in 2013, I wired it as per Nigel's post #6, cost about £5, took 15 mins, and it is working/has worked perfectly, ever since.

Yes I saw that. I am merely pointing out that "You don't need two DPDT relays. Doing it that way is so overly convoluted." The use of two single pole double throw relays is all you needed. Less wiring and way less complicated (convoluted). Not here trying to get you to change it, agint just pointing that out. If anyone else want to do this they can read this and if interested they can just ask or Just look up Power windows and lock diagrams.

 

[mouthpear]

Wow this thread is very old. Back in 2013, I wired it as per Nigel's post #6, cost about £5, took 15 mins, and it is working/has worked perfectly, ever since.

So how long did it last?

 

[PaulRainbow]

So how long did it last?

If JFM wired it up in 2013 and it's still working, i guess it lasted 11 years.....so far.