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# Garage Door Opener

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#### Fuzzygrowth

##### New Member
Hi folks. This is my very fist post here. I found this website this morning looking around for a way to step down my girlfreinds 12v car battery to operate her 9 volt garage door opener remote control. I have no idea what i am doing, i thought i could just stick in a resistor and was hoping that the guy at radio shack would tell me which one. Now i'm in trouble, she's expecting this and i have no clue what i am doing. ( but i can't tell her that) So i am really happy i found this forum. Can anyone tell me what to goto radio shack and buy? I want to hook it up so that the actually garage door opener and any other componets are under the hood somewhere and only the button going inside the car. Any help would be great. Thanks people

Hi, This quite simple actually. Though if you check her car battery it is most likely anywhere from 12v up to around 15v. You need to find out what the amperage draw is of the transmitter should be really low in the mA. To find resistance value- (Rs = Vin - Vout / I) Where V-in is your voltage from your battery, we already know that the transmitter is 9v so thats going to be around 3 to 4 divide that by your amp draw (I) ...i.e 0.04 is 40mA, to get your resistance. Then go buy a 1/4 watt resistor in the nearest value, go larger rather then smaller add in series with your positive voltage and that should work. Good luck

Mxitman :wink:

Perhaps a 7809 voltage regulator would be a safer bet, little more expensive than a resistor but will be unaffected by changes in the input voltage from car electrical system.

I am not sure as to put only a resistor. I wold use a Zener diode 9.1V, and use a ressitor to limit the current to the diode. This way you are warranty a 9.1V. You should be able to find this parts at Radio Shack.

Good Luck

Ivancho

how will i know the power draw from the transmiter? i mean... how will i measuer how many m.amps it uses?

and also.
"I am not sure as to put only a resistor. I wold use a Zener diode 9.1V, and use a ressitor to limit the current to the diode. This way you are warranty a 9.1V. You should be able to find this parts at Radio Shack. "

do run the a resistor then the diode, then into the transmitor in series on the hot wire? And also what resistor are you telling me to use exactly?

I did read a couple of threads regarding that 7809 thing but i basically have no idea where to get that or even what it is. i do like the idea of just putting a resistor and this diode thing though.

No thinking about resistor and zener. The regulator give safety.

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Sebi... where do i get that? can i buy it at radio shack? do i just ask for 7809? Now that i've seen a picture of it it looks pretty simple. Thanks again

I don't think Radio Shack sells the 7809.
They do carry the LM317 adjustable voltage regulator.
It needs a few extra resistors to set the voltage.
220 ohm resistors RadioShack # 271-1111
680 ohm resistors RadioShack # 271-1117
.01 uf capacitors RadioShack # 272-160
Please note the LM317 pins are different from the 7809 regulator,
and not representative of the position in the schematic.
Also the main body 'tab' is voltage out, not ground.

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The 7809 is also a good idea. You can find a 7809 at Digi-Key here in the US, but the inconvinient part is that you are going to pay more for shipping and handling :lol: Here is the part number you want: Digi-Key Part Number NJM7809FA-ND

The Zener will work as well and would be faster to build. You just connect a 82 ohm 1/2W resistor to the 9.1V zener 1W and voila! If you wish to add protection you can always put a fuse in there a 0.5A fuse will sufice

The best is that you pick up the LM317 at Radio Shack

Good Luck,

Ivancho

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Also, what does 220 nF mean?

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Don't rule-out the single resistor idea at the front of the thread. Some circuits can draw from the car's battery all the time while the resistor idea only draws when the opener is operated. Your girlfriend might not be happy with a dead battery. This is not high tech electronics - just an opener and it will work with slightly varying voltages as long as they are near 9 volts.

the "little signs" are capacitors
they are kind of like little electron buckets that stabilize the device
a farad is too large of a measurement for most common devices
micro farad is often labeled uf or mf
nf is a way to label micro farads without using decimal points
my diagram shows .01 uf which is 10 nano farads
the value isn't too critical
I used that size because I noticed they were cheaper at Radio Shack
it is all terribly confusing until one gets use to it

dipp switches in garage door openers

can anyone give me a description of how and what the dipp switch is doing in a remote control ?hanks

Dip Switches

I know this post is quite old, but I just wsanted to post an FYI for anyone with the same question in the future. To program the remote with dipswitches to work with your garage door opener, you need to look at the back of the power unit in the top of your garage and match up the dipswitches on there to the ones inside your remote. You should change the switches on the power unit so that they arenotfactory default,however to improve the security. Once you have matched up the switches, the remote should work.

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