Integrating garage opener

You can make yourself a really compact (&cheap!) voltage converter/regulator with parts available from Radio Shack - you only need three components!

Get yourself an LM317T and connect two resistors up as shown in the image below - the values of the resistors will determine the output voltage based on the equation Vout = 1.25*(1+R2/R1)

For this case, for Vout =3V (per your requirement), select resistors of 240 Ohm for R1 & 330 Ohm for R2

Using the equation Vout = 1.25* (1 + 330/240) = 1.25* (1+ 1.375) = 1.25*2.375 = 2.97V or ~3V

Here's a resistor calculator link to determine the values for those who are mathematically challenged!

You can eliminate the capacitors shown in the calculator schematic - they shouldn't be necessary since you're dealing a with a DC/DC conversion.

Actually it will be easier to find single preferred resistor values of 470 ohm & 680 ohm which gives 3.06V - you can also either use a potentiometer for variable or just make up the resistor value with two individual resistors (e.g. 240 = 120 + 120 which are more readily available as preferred values)  Resistors come in packs of 5 anyway at RadioShack so no extra cost involved, just another solder joint.

For those of you with 9V remotes incidentally simply use 1.5K for R2 (with R1 of 240 ohms) to give 9V out instead of 3V

They'd have a real hard time stealing my remote ;-)

It's up behind the instrument panel now.  That's why I really wanted to give it a power source, so I wouldn't need to ever worry about the batteries again.  Even though I've become quite an expert at getting it all off, I'd rather avoid it. 

I just ordered an automatic headlight kit.  I'm thinking that'll be the last electrocal tweak I'll do for the Jeep (beyond adding the radar and tilt sensors).  Those are prewired so no hardship.

I've batted around power windows.  They make kits for the Jeep making the buttons look very OEM, but I am even to the point of taking the Jeep emblem off of it for fear of embarassment.  I mentioned to a buddy who is a Jeep purist I added the door lock actuators and he went off the deep end.

But then again he won't recognize it as a Jeep anyway because it has an AT and AC.

heheh

Joseph

Outstanding!

You just saved me about $15 and gave me a project :)

Thanks!

No problem - very simple little project that you'll feel good about making.

Probably find a dozen uses for these now!

You could consider making it on a small board ( like this one) - it should fit nicely in the std battery location.

Unfortunately I don't follow this.  If I increase the resistence, either the voltage or current will need to drop.  I don't want the voltage to drop much below 3V... But at the same time, I don't want a fire under the dash from a board melting either...

What values would you recommend for R1 & R2 above?

Basically, I'm just the yahoo at the end soldering it all together ;-)

Joseph

From the application notes from the device manufacturer the recommended value for R1 is typically 240 ohms with R2 scaled appropriatley.

Your recommendation to select high resistance values not only goes against the design spec but also is completely unnecessary - you are talking about a total power dissipation of less than a 1/4W.

No need to make this complicated with confusion over excessive power drains thatfrankly aren't an issue.