# 12v reversable relay problem

Discussion in 'The Projects Forum' started by chicken12, Nov 24, 2009.

1. ### chicken12 Thread Starter New Member

Nov 24, 2009
4
0
Hi, I have a project where I have a pair of linear actuators lifting up a roof on a small storage shed where I keep salt water for my fish tanks. I picked up a pair of linear actuators from Firgelli Automation. They work great. I figured I would pickup their remote control also so I dont have to go inside to open up the roof. The problem is the contacts on the remote are not rated high enough to handle the pair of linear actuators. The linear actuators have stops built in on both directions, so all I need to do is take the two wire output out of the remote control receiver. The receiver has 3 states, off, up (output is + / - ) or down ( output is - / + ) I was thinking some sort of DPDT relay but I cannot seem to find any information on a relay that will close one direction when +/- is applied to the coil and the other direction when -/+ is applied to the coil. Any ideas? I appreciate it. Thanks!

2. ### kubeek Expert

Sep 20, 2005
5,585
1,094
What about two relays and two diodes in series with the relay coils?

3. ### SgtWookie Expert

Jul 17, 2007
22,201
1,809
Kubeeks' idea could work.

Give us some more specifics about the linear actuators.
What voltage do they operate on?
What is their current requirement?

Tell us more about the receiver. It has a ground output and a + or - signal output, right?

What voltages does it output, and at what is the rated maximum current for the output?

When it is off, is the output at a high impedance (open) or is it the same potential as the ground output?

4. ### chicken12 Thread Starter New Member

Nov 24, 2009
4
0
Its just a basic two wire system that flips polarity to change directions or drops all voltage to stop. There is no signal / ground outputs.

The linear actuators are 12vdc ~4amp each.

http://www.firgelliauto.com/product_info.php?cPath=90&products_id=5

The remote is also 12vdc but its contacts are only rated at 5amp. I need to run a pair of the actuators on a single channel as the roof is large and heavy.

http://www.firgelliauto.com/product_info.php?cPath=100&products_id=18

Please let me know if there is any other information I can provide. Thanks again!!

5. ### chicken12 Thread Starter New Member

Nov 24, 2009
4
0
bump. thanks!!

6. ### SgtWookie Expert

Jul 17, 2007
22,201
1,809
OK, sorry you fell off the radar. We've had a lot of posts, and this simply slipped our minds.

I'll have something in a jiffy for you.

[eta]
OK, here it is, warts and all... note that I have not included a fuse between the 12v supply and the motors, which is a no-no. You should use a circuit breaker or fuse to protect the rest of the circuit, rated for less amperage than anything else in the circuit. Otherwise, you will probably wind up with a big fire on your hands. I'm not kidding.

The diodes D1, D2 select which relay coils are energized at any given time. The system relies on the internal limit switches of the linear actuators.

Ideally, the remote would sense when the linear actuators stopped drawing current, and turn itself off, thus turning off the power to the relays.

If the remote stays on, the relay coils will draw power continuously.

RLY1 and RLY2 can be any automotive SPDT relays.
D1 and D2 can be 1N4001 through 1N4007, 1N5401 through 1N5407 or many other diodes - but not 1N914/1N4148; they won't take the current.

[eta]
Added D3, D4. These are a must. Anything in the 1N400n series will be just fine.

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Last edited: Nov 26, 2009
7. ### chicken12 Thread Starter New Member

Nov 24, 2009
4
0
There is no need to appologize. I am the one asking for help here Have a great Turkey Day!!

8. ### SgtWookie Expert

Jul 17, 2007
22,201
1,809
I think I have a solution posted for you already.

Happy Turkey Day to you, too.

9. ### THE_RB AAC Fanatic!

Feb 11, 2008
5,430
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Wouldn't he be having a Chicken Day???