Re-Packaging Homelink Automotive Universal Remote Controls
Garage openers for cars are a pretty simple thing. Stick the thing on a visor or in an unused ashtray, or leave it in the console, and it's always handy. Motorcycles make things a little more annoying. Gloved hands reaching into pockets don't work so well, and garage openers in pockets don't work out so well either. The buttons get pressed and batteries wear out, or the cases stab into you or get damaged, and can even injure you in an accident. Dismounting the bike and using keys is far from convenient, and who wants to go digging into a tankbag or tailpack for keys or the opener every time.
Envious of the convenient Homelink transceiver built into the overhead console of my Honda Accord, I decided to equip my motorcycle with its own built-in garage opener. The first idea that came to mind was to velcro a spare remote onto the bike somewhere. The remotes my building uses are usually leased and if you can buy one, they're more than $100. That's a bit expensive for something that probably isn't even durable enough for the vibration and the humidity and temperature swings anyway.
Unfortunately I discovered that due to our system's somewhat unusual operating frequency - 295MHz - and the recent abuse of the DMCA laws to rid the market of most RF learning remote controls, only the Homelink programmable remote control systems would work for me. Problem was, at the time the Homelink transceivers were available only as OEM accessories in automobiles. And according to Johnson Controls, they would never be available in portable applications. Darned party poopers...
Well, Johnson Controls eventually did wake up and licensed Homelink to Mito Corporation, who introduced a Homelink motorcycle garage opener at the 2006 International Consumer Electronics Show and got it to the retail market sometime later that year with sufficiently little fanfare that I didn't come to know about it until a year after (and two years after this adventure described here). But congrats to Johnson Controls and Mito Corp anyway, and hey, it only took y'all a decade! For a healthy $150 or so you can finally have a portable battery powered Homelink transceiver of your own. I still like my solution better...
Lack of retail availability was no obstacle to me of course. On eBay I located a Homelink -equipped overhead light console from an auto salvage dealer. A quick word of advice here, particularly if you have a queer garage system like we have - choose something from at least the year 2000 or so - not all Homelink transceivers are equal. If you're patient, you should be able to snag one of these in good shape for under $50, shipped.
The photograph on the left shows the transceiver circuit board and the button/LED circuit board connected together by a ribbon cable, just before being removed from the part of the console that held it and the two overhead lamps along with sunglass storage compartment, etc. Getting there is not easy because all the major plastic pieces are welded together. Just work slowly and use flush cutters to snip away the welds as you go.
I saved the FCC sticker from the assembly to use in the transceiver's new case, figured out the power and button wiring, did some measuring and ordered up a suitable plastic housing. I chose part # 537-400-I-BK from Mouser Electronics.
This would work nicely for me since I didn't need room for the original buttons and LED. It turned out that the inner dimensions of this plastic housing were actually just a smidgen too narrow, so I cut shallow slots into the inside walls of the housing and did some careful filing on the edges of the circuit board. The Homelink transceiver circuit board now snaps neatly into the slots for a durable, vibration -resistant assembly.
The photograph on the right shows the transceiver snapped into place, with just enough room for the various wires to snake underneath. The 12V power wires are soldered onto the protruding part of the circuit board, + on the bottom, - on the top, middle un-used. The wires for the push button and the indicator LED are seen coming from the opposite side of the circuit board (a wiring guide is shown here below). Holes were drilled into the case walls for the wires as necessary, just large enough for the chosen grommets and wires.
Two foam rubber "feet" were adhered to the inside of the case lid to help secure the board against vibration. They are set to press lightly against the antenna, which is the long metal piece on the upper edge of the circuit board. You can see the impressions in the rubber.
Sharp-eyed readers may notice that the circuit boards used in the two photographs are slightly different. One circuit board was damaged due to an electrical gaffe during testing so I had to purchase another console.
The assembled housing is now hidden safely inside the motorcycle's fairing, fastened to the machine with 3M Superlock (aka Dual Lock) for a secure and easy to maintain installation, all wiring openings sealed with tight rubber grommets and silicone sealant, and the device is wired to the bike's taillight circuit so that it is only usable when the ignition is "on" for security.
As far as wiring requirements go, the transceiver draws over 250mA, but even thin #28 wire is more than enough for that. I happened to use a heavier gauge wire because it was simpler to mate to the crimp connectors I have, and it's more durable. Always use marine -grade power connectors and wire for motorcycle work, and use professional crimping tools! I recycled part of an old USB cable for the button and LED wiring. The USB cable is fairly flexible, heavily jacketed and durable, and the small wire gauge lent itself well to being soldered to the pads on the circuit board. Remember to provide strain relief at the grommets! Don't want those tiny wires getting pulled loose now.
Always thinking about maintainability and durability, I used weatherproof quick disconnects in all the wiring for power, buttons, etc. In case you're wondering about the big focus on durability, New York City streets and all-weather riding can quickly take its toll on anything less.
The last challenge was to find a weatherproof pushbutton with a shallow enough panel depth design to fit the location I chose.
It took hours of searching the Internet and scouring the catalogs of major electronics suppliers such as Digi-Key, Newark and Mouser. I eventually found a delightful solution in Apem's IP series pushbuttons. There are plenty of other weatherproof pushbuttons with broader retail availability if you have a little more room. This style happens to blend nicely with the bike, as if the button were OEM equipment.
Homelink systems offer three programmable buttons but I used only one, at least for now. The button was placed within easy reach (just under the rearward portion of the windscreen) and is located in a way that even winter gloved hands could easily operate the button with a ham-fisted squeeze.
The only tricky part in all of this, really, is getting the button and LED wiring correct. The table below shows the wiring pattern for the transceiver circuit board, as if viewing the back of the board with the power connector on the left and the pads for the button/LED cable in the lower right corner. In practice the ground plane is not used. All switches are momentary NO (normally open). The LED can be any standard ~20ma LED. Take care not to short any of the pads during soldering. Even without power applied, the transceiver is "live". You don't necessarily need the LED in normal operation but it's important during programming.
unused unused LED - LED + middle switch right switch left switch 12v - switch common 12v + ground plane
It's not that big a deal to transplant the Homelink circuit board as long as you can fish it out without damaging it, and get the wiring correct. Other tinkerers may choose to keep the original integrated buttons from the console, which at the cost of some extra creativity required to design them into their new fixture certainly makes the electronic aspect easier.
My end result compared to the products offered by Mito is that my garage opener can't easily be abused to facilitate the theft of my own vehicles or other vehicles in the garage, it can't be easily stolen or vandalized, I never have to worry about the battery or about the unit's weather resistance and durability, and my installation is not at all obvious.
