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okhotwire
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Join Date: Sep 2008
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12-VDC Reversing Relay Control for Door Actuator

09/15/2008 4:24 PM

I am trying to control a 12vdc door opening actuator with a 12vdc photo cell, and a 12vdc timer relay. I have the photo cell and the timer relay. I am just not sure how to go about reversing the polarity to the actuator to make it open and close. I am using the photo cell so that I can leave it open all day and close at night or during a dark cloudy day. Using the timer to control the time for the actuator to complete its cycle. I am sure this is simple with a couple of more relays, though just not sure.
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Bolton_Alan
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#1

Re: 12-VDC Reversing Relay Control for Door Actuator

09/16/2008 4:05 AM

Dead easy.

Use a DPDT relay, connect 12v to NC on 1 pole and NO on the other. 0v to the opposite contacts, connect door actuator to the common terminals and energise the relay coil with your photocell.

Al

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JohnDG
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#2

Re: 12-VDC Reversing Relay Control for Door Actuator

09/16/2008 4:22 AM

This should do it ...

With the relay de-energized (as drawn), the motor will drive (hopefully in the CLOSE direction!) until the CLOSED limit is hit.

With the relay energized, the motor will drive in the opposite direction until the OPEN limit is reached.

[Edit - this is safer than using the timer relay for open/close cycle. Unless you have a slipping clutch, you can do nasties to the motor and/or gearing. Something's gotta give!]

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Bolton_Alan
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#3
In reply to #2

Re: 12-VDC Reversing Relay Control for Door Actuator

09/16/2008 4:32 AM

John has been good enough to draw the same solution as I have described.

It will work.

Al

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okhotwire
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#7
In reply to #2

Re: 12-VDC Reversing Relay Control for Door Actuator

09/16/2008 6:14 PM

Thanks alot for your time....I do appreciate it! I think I was over thinking it....I knew there was a simple solution for this issue!!!
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JohnDG
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#4

Re: 12-VDC Reversing Relay Control for Door Actuator

09/16/2008 4:47 AM

Another thought ...

If there's any chance of personnel accessing the area where the door is, you'll need warning signs all over the place (ATTENTION! THIS DOOR MAY OPEN OR CLOSE WITHOUT WARNING), and either a Safety-rated slipping clutch or some other safety device (light curtain, safety mat or safety edge). An audible & visible (flashing light) alarm may also be in order.

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barfnagler
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#5

Re: 12-VDC Reversing Relay Control for Door Actuator

09/16/2008 11:56 AM

what do you term as a electric door actuator? without knowing what you are working on or trying to repair fix modify create r whatever it is you are doing you run the risk of getting well intened and applicable advice but it could well backfire on you.

some people call a door actuator a device similar to the old doraide product the new besam or stanly systems.

othere refer to a door actuator as a electric strike or a power opener what is it you have.

the backfires range from the sudden open close of the door to a unintended imprisonment of the occupants. relate if the system is normal hold open or hold closed whose product and model number you are working on. THIS DEFINITELY NOT something to experiment with if you do not know what you are doing and intend to have it in situ for ANY application.

'da ber
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okhotwire
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#6

Re: 12-VDC Reversing Relay Control for Door Actuator

09/16/2008 6:08 PM

I want to thank everyone for their help. Accidental entrapment is a possibility.....though if this happens, that poor coon or tree rat will just have to patiently wait for it to open again!!!! This is for a deer feeder that I am trying to open during the day light hours only and to close if it was to cloud up and start raining!!
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JohnDG
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#8
In reply to #6

Re: 12-VDC Reversing Relay Control for Door Actuator

09/16/2008 7:20 PM

Sounds like the warning signs and Safety-rated stuff won't be needed, but if you're feeling real coon/tree rat friendly, you could string a buzzer in parallel with the motor!

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JohnDG
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#9
In reply to #6

Re: 12-VDC Reversing Relay Control for Door Actuator

09/17/2008 3:57 AM

Just another thought - check what current your motor draws (start & run). Make sure you use a good chunky relay - they're notoriously prone to contact welding with DC inductive loads.

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barfnagler (1); Bolton_Alan (2); JohnDG (4); okhotwire (2)

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