SSR for use with Garage Door Opener Remote Control

Hi,

i want to use the Electric Imp and a April Board to simulate a Button Press on a Garag Door Remote Control.

the RC is powered with a 12V Battery (this one: http://www.ebay.com/itm/Vinnic-A27-Alkaline-12V-Battery-G27A-MN27-GP27A-AG27-L828-/390384405092)

Can you recommend a SSR or Relay to use with the Imp?

I like this one: http://www.abra-electronics.com/products/COM%2d10636-Solid-State-Relay-8A-125VAC,-S108T02.html

Any hints before buying the above SSR?

thx
Chrischi

An SSR would work but it’s rather overkill, especially as the amount of current being switched is just a few milliamps.

You could do this with two FETs as I was talking about for imp power control. If you’re comfortable with building that on a breadboard I can give you a circuit that’ll work with an imp…

I would like to see the circuit. Should be no Problem to build it on a breadboard.

We used a relay, across the remote push button to “pulse” the garage door remote. This Grove relay will run from 3.3 V to 5 VDC and even has a relay status LED.

http://www.seeedstudio.com/depot/index.php?main_page=advanced_search_result&search_in_description=0&keyword=grove+relay&x=26&y=9

@impandy nice! where can i see your project? What’s the current of your garage door remote?

nice! where can i see your project?
It's for another "high cost" wifi controller http://arduino.cc/forum/index.php/topic,50887.msg391594.html#msg391594
What's the current of your garage door remote?
Since most wired push button remotes are powered by the garage door system it is not a concern like Hugo said above. As you can see , from my project, you need more than a NO relay across the remote push button for proper operation.

i’am talking about a wireless remote control. Like you see in my first Post. You are using the wired button, right?

As you can see from the project safety is the number one concern. By using
a RF remote and opening/closing the garage door is not what I call being safe.
In my project, I have warning indication for pending door closure and IR sensor
to detect objects or humans in the garage. Proper open/close status feedback feedback is also necessary and all this cannot be done without wiring in the garage. So the answer is Yes I am using the wired push button remote in the garage.

@chrischi, see attached picture. This will switch voltages up to 30v on and off using the imp’s 3.3v (or a 5v arduino, or whatever… it needs >2.5v to switch).

How it works:

The PFET at the top turns the load on and off. In order for the PFET to turn on, the gate (G) must be at least 3v below the source (S). For the PFET to turn off, the gate must be within 1v of the source.

As we can’t generate 12v from the imp to turn the PFET off, we use a pull-up resistor to connect the PFETs gate and source pins. This means by default the PFET will be off (drain not connected to source, so no current flows to the load).

In order to turn it on, we need to pull the PFET’s gate low. We can’t do that with the imp directly, because the imp can’t withstand more than 3.6v on its pins. So, we use an NFET at the bottom to pull the PFET’s gate down to ground.

To turn the NFET on, which in turn turns the PFET on, the NFET’s gate needs to be at least 2.5v above its source (which is connected to ground). The imp can do this no problem. Program the imp pin to DIGITAL_OUT and set it to 1 to turn your 12v load on, or 0 to turn it off. As the pin will float when the imp is not in the socket or uninitialized, you may also want to add a 100k pull down to the NFET gate/imp pin.

You can switch a couple of amps with this circuit, and basically zero current flows from the imp’s pin (a tiny bit will if you have a pulldown).

Hugo, thx a lot! :-bd

i ordered the parts today and will give you some feedback after i build it.

@Hugo

had the time to build the circuit and it works like a charm.
What do you think how much amps i can switch with the circuit?
Any concern about the common ground of the imp and the other circuit? (RemoteControl 12V)

Current is limited by the DMG2307 - so at 12v you could do a few amps.

There shouldn’t be a concern about the common ground (it absolutely requires a common ground).