Joe's Toy

Hey guy's I'm taking my big annoying garage door remote and going to install it into my maplight. So I started by taking the circuit board out of the the big plastic shell it was in and figuring out where I'm going to hide it in my headliner. I was exploring the possibility of wiring my 9 volt remote into my 12 volt vehicle's system. Here's my question How do I create a circuit that drops the 12 volts down to 9 volts before it reaches my device? I've googled and found what seamed like a easy answer using resistors but after trying it I'm not seeing any voltage drop. Any links, equations or just the flat out simple answer (like "solder 3 x 30 ohm .5 watt resistors in series and your good to go") you can provide me with would be greatly appreciated.

Plan B is just leave the 9 volt battery attached.

UKrunner

http://search.digikey.com/scripts/Dk...7809CT-BPMS-ND

Click the link to the datasheet, which is on that page, on how to connect it up. You might need to find a heatsink to fit it. I don't know the current draw of your garage door opener. You *should* be ok though.

4Crawler

iTrader: (3)

Radio shack carries a 9-volt adapter you could use:
http://www.radioshack.com/product/in...entPage=search

Resistors will work if it is a constant current type of load (like the LED mentioned earlier). However, if the device uses a variable amount of current, then you'll need a voltage regulator, such as what is in the adapter above.

INFINITY

i would just go by radio shack and ask one of them to get you the conversion equation and resistor to get you to 9v. i have done this for installing LEDs into vehicles. also it is like $1.50 for a pack of 5 resistors. just wire one inline on the + lead.

Joe's Toy

hey guys thx for the replys. I went to radioshack to ask the "experts" lol but they all told me they couldn't help me. That addapter might b the simplest way. I'll just take apart the casing and solder it in the system. W/ the circuit already made for me. Do u guys think that would be cheesy? (sry if this MSG is totally retarded. I'm typing on 1 of those iPod touches.)

Noltz

You can't "read" a voltage drop across a resistor. You must have current flow, and know the load of the accessory you're using. A Zeiner (sp?) diode can limit voltage, but I'm not familiar enough to offer any advise other than to look it up.

I'd go plan B. For the number of times you need to change it, why bother.

Joe's Toy

Haha that statement summed it up perfectly! I've had garage door openers last for up to 4 years without changing a batt. It would be pretty silly to go through at that trouble over dealing with a dead battery in 3 years.

Thanks For all the advice guys.

GVOLCRunner

Amen to that. its not worth it. That garage door opener takes SO little power for the half second you use it, why waste the mental enegry to wire it in.

That being said, you need a resistor and wire it in.. only its not that easy. I would imagine that the garage door dosent draw all 9volts and the circuit board draws it down. You would have to figure how to wire it in. But, in simple speak a resistor "absords" enegry thus knocking it down to a specific level..

js9924

12v regulator $5 about 100 ohm resistor $1 and thats it

93ToyKid

this thread made me barf. i just got finished taking an intro. to electrical engineering. i'm a mechanical, so obviously it messed me up. the zener diode statement just brought back bad memories...

SLOMatt

As UKrunner posted above, you just need to get a cheapo voltage regulator. I doubt your opener draws more than .25w so you probably wouldn't have to worry about heat dissipation. You can get an adjustable LM317 at radio shack for a couple dollars and then you would just need a couple resistors to set the output voltage at 9v.

- Matt

Joe's Toy

well maybe it wouldn't be so hard after all. I wired up the garage door opener ran the button, it worked like a charm and then as soon as I clip thatnstupid plastic shroud under the mirror on it won't broadcast the signal strong enough I guess... I'm going to relocate the main opener modual from my headliner to my engine compartment and see if that helps. Then I'll have enough room to
think about adding the convertor. Thx gentlmen!

Steveebryant

Hello, I am interested in supplying the DC voltage required from two AAA 1.5 volt batteries to a motion detector that I will place in my truck. When I leave my truck, I will turn on the switch that will power the motion detector. If someone enters my truck, the motion detector will send a signal to the receiver in the house and sound an alarm signal. I have used this detector system before but it runs down the two AAA batteries too quickly for me so I want to take the power from the truck battery.
Is there anyone on this forum that could actually help me in the details required to construct such a circuit or might there be some one here who could direct me to someone else that could help? Please, thanks, Steve these are neat

4Crawler

iTrader: (3)

Check out Radio Shack, they have small voltage convertors that have different output voltages that would probably work.