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Installing a Garage Door Opener Wired to Motorcycle Hi-Beam

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I was tired of having to get on and off my bike to open and close the garage door each time I headed out.  While my wife and I were out of town we found a project at a dealer that allowed you to operate the garage door via the hi-beam switch.  It was $120 and more than we wanted to spend at the time (times two since we'd each want one on our bike).  Recently, however, I decided, "how hard could it be to come up with a simple circuit to trip the garage door opener from an existing circuit on the bike"?  The first one took a few hours of research, building, and a bit of trial and error.  This instructable includes the step-by-step instructions I used for our second bike to put it together in under an hour for $15 plus a garage door opener.
 
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Step 1: Parts Needed

Here are the parts needed (Radio Shack mode # in parentheses):

 - 12VDC/125VAC 10A SPDT Mini Relay (275-248)
 - 1000 microfarad 35V 20% Radial-lead Electrolytic Capacitor (272-1032)
 - 10K ohm 1/2W 5% Carbon Film Resistor pk/5 (271-1126)
 - Project Enclosure - 4x2x1" (270-1802)

In addition, you'll need a garage door opener.  I used a Chamberlain Universal Garage Door Opener that I found at Lowes. 

For a nice, clean installation, I'd pick up some 18g hook-up wire, heat shrink tubing, and some wire-tap-in's.  You'll also need a soldering iron and solder for making the connections.

I cannot find this relay. Radio shack no longer carries it. Are there any other variations or relay sizes that would work?

bkrabach (author)  nathan.hemenway18 days ago
If you do a Google search for "12v 10a spdt relay" there are a number of options under the "shopping" category at the top of the results page. Looks like a lot of options on eBay for just a few bucks. If you end up buying one at an online store, please post back to this thread and help out the next guy looking for one.

Thanks!
Sidecar Bob2 years ago
The circuit at http://www.the12volt.com/relays/page5.asp#ctm shows a diode between 85 and 86. Is there a reason you left it out?

I found the same setup on a forum (not as well presented as yours) and someone there mentioned that the remote activated when they switched to the high beam on and again when they switched back to the low. IIRC, someone else replied that theirs did that too until they added the diode.

Also, is there a reason for using 3 x 1K resistor in parallel instead of the single 1K resistor in the original circuit? And why did you use 3 x 1K instead of a 330 ohm resisistor?

BTW: I am intending to build one of these myself tomorrow. I have a Genie opener and the remote runs on a 12V battery so I will be able to power mine from the bike. As a bonus, I think I can fit the relay & other components in the space where the battery used to go so I won't need a project box.

Thanks in advance,
Bob
bkrabach (author)  Sidecar Bob2 years ago
Bob,

I'm not familiar with that particular circuit - mine was from a collection of notes I made while researching the general concept of building momentary switches from a constant feed gathered from a handful of different sources. So, could the diode be added, could you use a single resistor? Most likely - this is just how I chose to build mine. Feel free to try something different and if you find something that works better, please add it to the comments for the benefit of any others who browse this project.

As for the remote activating when switching on and off - yes, the diode should resolve that issue. The other resolution, I found, is to simply swap the wires when attaching to the hi-beam circuit. I performed this upgrade on two bikes and on one of them, I accidentally had them backwards and this is exactly what happened. When I performed the second one (the one documented here), it works perfectly as desired. I went back and switched the wires on the first one I did and now it works great as well.

My opener uses a 3V supply, so I did not wire it into the battery (yet). I was thinking of coming back to build a circuit to step down to 3V, but for as infrequently as I'll need to change it, I probably won't ever get around to it. If I'd have had one that used a 12V supply, I definitely would have wired it in though.

We recently upgraded our headlights to LED and our project box no longer fit behind. As a work around, I pulled them out, wrapped them with a protective foam sheet and sealed the open end with tape. It's not as pretty as the above design, but it now fits again and still works great.
I did some experimentation and some more research.

When voltage is applied current flows through the relay's coil and the capacitor, charging the capacitor. When the capacitor is fully charged no more current flows so the relay turns off. When the voltage is removed the capacitor discharges through the resistor so that when voltage is applied again the capacitor will charge again.

The value of the resistor determines how fast the capacitor discharges when you turn the high beam off, and thus the the time you need to wait if you want to activate the remote again. From my experimentation, 3.3K ohms (the same as 3 x 10K in parallel)(330 ohms as I originally said was a typo) turns out to be just about optimum, allowing the circuit to be triggered again in a couple of seconds while 10K takes almost 10 seconds and if the value is reduced much below 3.3K enough current flows through it to activate the relay whether the capacitor is charging or not.

I have a feeling that we both found this circuit at the same place (I still say your presentation is easier to follow) and the person who posted it bought the same back of 5 resistors that you did and then did the same experiment I did but with parallel combinations of 10K resistors instead of various values of single resistors. The end result is the same.

The diode is there to protect the relay and other electronics from reverse polarity spikes which occur when the voltage is removed and the magnetic field in the relay's coil collapses. It does not have any effect on how the circuit works (I did not experience the remote activation when the high beam was switched off), but I think I will include it in my build.
Hey Sidecar Bob. I'm hoping you can help.
I currently have this setup using the 3x10K resistors and I find it's just not quite long enough of a press for my system. It's about 1 second or so and I've rather have around 2-3 seconds.
Any ideas what configuration of resistors I would need?
Thanks for any help you can provide
By "not quite long enough of a press" do you mean that the trigger duration (how long the remote is turned on) is too short?

As I explained before, the resistor is only there to allow the capacitor to discharge when the power is removed from the circuit. Changing it will only affect how soon you can trigger the circuit a second time.

To increase the trigger duration you need to increase the value of the capacitor (a larger value capacitor will take longer to fully charge so the relay will be turned on longer). I didn't experiment with that when I was building mine but If I wanted to make the remote stay on that long I would start by trying a 5000Mf capacitor and see if that helps.

BTW: I found this setup to be less reliable than I would have liked. For various reasons I decided to replace the handlebar switches on my 30 year old Honda with modern Royal Enfield ones. The Enfield switches have a button to flash the high beam while passing (not required in North America and I find it easier to use the high beam switch for that anyway) so I wired that switch directly to the remote. This is even easier to use and extremely reliable.
Ah, gotcha. Thanks for the explanation. Clears up my confusion.
I might just end up switching this to an independent button and not worry about the capacitor/resistors anymore, if I can find a button that will mount up on the handlebars.
Thanks for the help :)
Daedalus622 years ago
Hi bkrabach, Nice work and good instructable, congratulations.

So, if I understood correctly, you're using the momentary hi-beam switch to activate the opener, right?

I did the same install in my bike but, as I was using an independent button/switch in my DIY dash, I just run the switched power directly to the opener (no capacitor, resistor, relay) and a couple of wires from the opener activate contacts to said button/switch. Done.

Your solution is great, because it avoids the use of extra switches, other than the ones already in the bike... Nice work.

Cheers
bkrabach (author)  Daedalus622 years ago
Daedalus62 > The hi-beam switch itself is momentary, but the circuit that it turns on (and that I've attached to) is a constant feed. That is what the capacitor and resistors take care of (See: http://www.the12volt.com/relays/page5.asp#ctm).

Without that element, the remote button is constantly "pushed", draining the battery on the remote non-stop whenever the hi-beam is on.

With this solution, there is no power being supplied to the remote, it's simply closing the contact points on the button (via the relay). This way, it does not matter that the bike circuit is supplying 12-volts and the remote operates at 3-volts.

Thanks for the feedback!
antennas2 years ago
What a great idea. The simplest ones are often the best!!
Mr Jaderman2 years ago
I believe you hooked the resistors up in parallel and not in series. Nice instructable!
bkrabach (author)  Mr Jaderman2 years ago
Mr. Jaderman > Thank you for catching that - yes, I meant that they were wired in parallel (per the picture).