By
connecting the garage door opener remotes ground to this lead, you can cause the remote
to activate whenever the TSC is pressed, if you connect the positive lead to the
motorcycles 12V system. The motorcycle will power the remote, so you will never have
to change batteries.

The concept is similar to the Autoswitch operation, but that product has a toggle action,
changing state once each time the TSC is switched. For the opener, you want a
momentary action, so that the circuit is active only when the switch is depressed and
returning to normal when you let go. The Autoswitch has a nice delay feature. There is
a potential to add a similar delay to this design, but Im still working on it.

Figure 1: Circuit Diagram Design
First, determine the power source for your garage door opener. Mine had a 12V camera-
style battery, which was lucky. Other common batteries would be 9V, 3V (2 AA or
AAA), or 1.5V (one AA or AAA). If some other battery than 12V, you will need a
regulator and/or resistor to drop the voltage to the right level. See Appendix A for the
design method.

Next, figure out how to bypass the momentary switch on your opener. Underneath the
button you press, there will probably be some kind of membrane switch attached to the
openers circuit board. Remove the battery, and use your multimeter in continuity mode
to figure out which terminals of the switch are shorted when the button is pressed. I
really wouldnt advise doing this kind of installation unless you have a multimeter and
know how to use it.

Installation
Solder a jumper wire across the remotes button switch terminals so that the switch is
bypassed. From now on, whenever there is power to your remote, the unit will be
sending the signal to your opener.

Solder a pair of wires to the battery terminals in your remote. If youve designed a
voltage converter, you need to solder that in too. You can probably put your converter
parts where the battery used to be. I used 24ga wire, but just about anything will do. I put
a connector on it to make installation and removal a bit easier.

These wires need to be connected to the motorcycles power and TSC leads. Youll
probably want to connect everything under the gas tank because all the wires are fairly
accessible. Connect the positive lead to a switched 12V source. I used the Green/Black
wire which supplies power to the heated grips. Connect the negative lead to the TSC
wire, which is Brown/White. With the bike off, you should use your multimeter to verify
that this wire is shorted to ground when you press the TSC. Use cable ties to secure the
wires to the frame up to the instrument cluster shelf.
You could also mount the remote (especially if it is small) under the seat. This will
provide the best protection from moisture as you wash the bike. I doubt this would affect
the transmitter range. I wanted to mount mine on the shelf under the instrument cluster,
so I needed some waterproofing. If youre careful when washing, and you dont ride in
the rain you might not need the waterproofing, but one day you will probably ruin it. At
least the Green/Black wire is fused, so you probably wouldnt hurt the rest of the
electrical system.

I have a vaccum food sealer, so I took a bag, cut off a corner, and led the wires out. Then
I filled that hole with silicone sealant, let it cure, and sealed up the bag with the opener
inside. I wrapped the whole thing in electrical tape in an attempt to make it invisible.
I taped the whole package to the shelf with double-stick tape. Voila!

I would like to add a �-second delay circuit to this design. Most of the time you use
your TSC for canceling the signals, and you hold the button for less time. Theres little
harm in firing the remote every time you use TSC, but you might re-open your garage
door as youre leaving home, or when you are checking your turn signal functionality in
the garage, you might inadvertently close the door on yourself. With some older less-
secure remotes, you might also open random garages and gates as you drive around, but
those people should get more secure systems (and so should you).
Appendix: Voltage Regulator.
If your remote does not use a 12V battery, you will need to include a voltage regulator in
your circuit. This does require some engineering, but its not terribly difficult. Feel free
to contact me if you have questions (or corrections), but remember Im just a hobbyist,
not an expert.

Regulators:
The easiest way to go is to find a solid-state (IC) voltage regulator chip with the same
output voltage as your batteries. Digikey.com or a good electronics store will have a
good selection, but with Digikey, youll need to buy other things to fill up your $25
minimum order, because the regulator should be less than $2. Radio shack sells a 7805
regulator which is 5V, but youll need a resistor to drop the voltage down to your 3V or
1.5V battery level. Ive used a 9V regulator in another project, but you could probably
get by with a resistor directly from the 12V bike power using the method below.

You can build a very simple regulator with a Zener diode, but youll still have to find a
good source of electronic parts. Radio Shacks selection is too limited. This web page
has a very simple calculator for picking the right parts. You still need to determine the
current drawn by your remote. You can estimate it, but you might end up with a
conservative design for which youll have more trouble finding the resistor.
http://www.csgnetwork.com/zenerdiodecalc.html

or
http://www.vwlowen.demon.co.uk/java/zener.htm


Regulators have a specification for amount of current they can handle and/or the power
rating (they are related), but a remote is designed to use very little current so that the
batteries will last. Therefore you can use the smallest IC regulator you can find

Resistors:
To get more voltage drop, you can add a resistor in series between your opener and the
voltage source or regulator. This isnt really the best way, but for this application it
should work fine. First you must find out how much current your remote draws when it
is active. Set your multimeter to measure current, then clip your meter in series with the
battery. Press and hold the remotes button until the current reading stabilizes. (Your
garage door will activate if you are nearby.) My opener draws I
opener
= 2.1mA.

I dont recommend using only a resistor if your remote runs on less than 9V, but it might
work. The problem is that the bikes 12V varies quite a bit, and your remote might work
intermittently or it might burn out prematurely if the dropped voltage varies too much
from the intended battery voltage.

The resistor you need is
R = (V
reg
V
bat
) x 1000 / I
opener

where
V
reg
is your regulator output, or 12 if are not using any regulator chip. V
bat
is the remotes battery voltage. If you have more than one battery, they are probably
in series, so you need to add up the voltages.
I
opener
is the value you measured, in milliamps. (the factor of 1000 essentially converts
this into amps.)

Battery voltage changes as the battery is used, so the resistor does not need to be very
accurate. If you get within 20%, you will probably be OK, but you are better off
supplying extra voltage than not enough, so a slightly lower-value resistor is better than
one thats too high.

Send comments or suggestions to
dunham@sfis.com