MOOREJT1

I currently have my garage door opener hard wired into my motorcycle's high beam switch. The nice thing about this set up is that the remote is hidden in the frame of the bike, it can not be easily stolen, forgotten or lost; and it can not be triggered unless the key is in the ignition. And I never have to change the battery.

My current configuration is as such.
1. solder a jumper across the button on the remote so that it is always in the on position.
2. Connect wires to the battery terminals on the remote. negative to ground, and positive spliced into the high beam positive source.

Any time my high beams are on, the remote is transmiting. The plan is to add a timer or toggle circuit of some sort such that when the high beam is toggled on, it momentaraly sends voltage to the 12 volt garage door opener and then shuts offf until the next time the high beam is toggled off and on. It was fairly simple to hard wire it such that any time the high beam is on the opener is transmiting, but I don't want the remote transmiting non stop just because I have my high beams on for safety.

I've seen black box devices on the web that do what I'm looking for, but I'd like to know how to build the circuit myself.

Any suggestions?

things

make sure the door opener is rated for 12 volts and higher, or it'll go pop!

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MOOREJT1

Yes, the opener originaly used a 12 volt battery.

Stellarcore

Sounds like a monostable 555 should do the trick. It even runs off of 12V.
A quick google search produces this website:
http://www.kpsec.freeuk.com/555timer.htm#monostable which has an example of a monostable timer circuit (theres also one in the datasheet for the 555 I believe).

Just hookup the main power supply for the 555 to the highbeam supply that you're using now and then hook the output of the 555 to the door opener.

Rolf

You have already got some workable suggestions, so I will just compliment you on you clever idea. I might use it on my cars, when I get "a round to it".

philba

I'd put a diode in series on the +12v to prevent battery reversals from destroying the opener.

picbits

Series capacitor on the feed with a resistor to ground.

Turn on main beam, capacitor has a high resistance for a short time until it charges up - you only need a short pulse to open most garage doors.

When the main beam is off, the capacitor discharges to ground through the resistor.

MOOREJT1

That sounds like it's exactly what I need. Would the resistor T off of the line before the capacitor goes into the positive input on the garage door opener? How do i determine what size cap and resistor to use?

picbits

Depends on how your headlights are wired up.

If its possible for the cap to discharge through the main beam with the switch off then I'd use the resistor on the side of the capacitor which goes to the RF switch.

There is probably a formula to work out what size cap and resistor you need but for starters try a 220uf capacitor and a 2.2k resistor. I'd also bung a 1N4148 diode in series just before the RF switch as a precaution against reverse voltage.

MOOREJT1

It's working great. The opener transmits for about 900ms before shutting off. All I have to do is flash the highbeam and up or down goes the door. Thanks for the help Picbits.

fiver

I have been working on a more complicated solution for the past two days and just found this thread. It's been a looong time since I did any circuit design and I am pretty rusty.

I could not get the simple resistor / capacitor solution propsed in this thread working in my circuit simulator (Tina Pro 6). Anyone have a simple diagram I can try?

Here is the theory of my current solution:

-Headlight is always on while Motorcycle is running. +12 from headlight provides power to 555 and rest of circuit

-555 is configured in monostable configuration, falling edge trigger. Each time the High Beam is turned off, the 555 trips

-555 output is connected to relay, which "presses" my garage door opener button for about 1/2 second each time high beam turns off (garage door opener is still powered by its own battery).

Schematic attached. I'm going to try to breadboard this in the next few days. I should be able to just press the "Flash to Pass" button on my handlebars and activate the garage door. Any comments are appreciated. Thanks!

Attached Images

garage.jpg (72.1 KB, 15 views)

fiver

I breadboarded my 555 timer solution and it was working fine. I ended up using different capacitor values. The timing simulations for RC circuits in Tina Pro 6 are way off so I guess this is not a good tool for designing these solutions.

After breadboarding and thinking about it for a few days I realized I was being an idiot, so I went with a simple RC circuit as described earlier in the thread.

Schematic below. The general theory of operation is the same, but now the relay is activated when the high beam turns on versus off. A great reduction in total components to use and one less wire to cut into on the bike. Installed this today and it is working perfectly. My neighbors were probably wondering why I was flashing the brights and giggling with the garage door repeatedly going up and down in 20 degree weather.

My garage door openers use 3v batteries. An enhancement to this would be to integrate a LP2950 into the solution, this way I wouldn't need to change batteries every few years.

Attached Images

garage2.jpg (27.6 KB, 5 views)

Pommie

You could probably replace the relay with a resistor and 3.1V zener to power the transmitter.

Mike.