I Make Projects

Posted on: May 24, 2018, by :

Theres not much to say here – just put the resistor in series with the + terminal wire (putting it onto the – wire will also work, but I like to put it on the + personally).

The arms of the Y go from behind the rear-view mirror, across the base of the sunshades, and then back across the tops of the doors. I tuck the wires under plastic borders to the upholstery and use twist ties wherever necessary to hook or otherwise attach the string of lights in place. In total, there are 12 lights (6 on each arm) which reaches just far enough around the cars interior to reach the rear windshield.

For some years now, I have had a homemade string of Christmas lights in my car which was adapted to run from a cigarette lighter adapter. I updated them recently to use LEDs; heres how to do it.

, solder the LED onto the wire. Make sure its securely soldered.

The string of lights is Y-shaped. The tail of the Y has the power plug which goes into the cigarette lighter socket. This powers the lights when the car is on. A bit of tape ensures that the wire stays out of the way and helps ensure that the results are sufficiently ugly and home-made looking.

A 47 Ohm resistor – It should be a beefy, high-wattage resistor since it will be getting quite warm in this configuration.I had a 10W one handywhich I used.

If you wish to play around with the number or type of LEDs, or the wiring, you should make sure your resistor is appropriate and your wiring layout is good. An LED calculator (there are many on the web -here is one of them- can help you here.)

And speaking of LED Xmas lights, you may also wish to check out myminiature USB-powered LED Xmas Treewith blinking lights!

This is an older site. For my professional site and contact information, visitAE Innovations. You can also visit my new site atIt Came From The Workshop.

Light it up by feeding +12V into the adapter plug, and after one last check that all the LEDs light up properly, Install it into your car!

First, it may be useful to measure out the cable inside your vehicle and mark off where youd like the bulbs to be and how long youd like the cable to reach. If you dont particularly care, you can just space them more or less evenly.

This design wires the LEDs in parallel which is easier to construct but requires a (physically) big resistor since the resistor needs to dissapate a lot of heat from the current it will be handling.

, bend the leads of your selected LED as shown. The longer lead goes to what will be the – wire. It is critical that you are consistent! All short leads of all LEDs should go to the same wire (and conversely, all longer leads should go to the other wire).

, cut a small hole in a table tennis ball – big enough for the LED to poke through.

Assembly is simple, but requires attention to detail since a mistake can – at best – result in a Christmas light string that partially or wholly doesnt work – or at worst, a short circuit being plugged into your cars electrical system.

Repeat until you have all 12 LEDs installed and secured. Then you can test by hooking the string up to a +12V source through the resistor. If all of them light up, youre set. (Otherwise, inspect the connections of any that dont light up.)

12 LEDs (I used 6 red and 6 green). The normal diffused ones are better than the clear high-brightness ones for this application.

Power comes from the accessory plug (about 12V or a little more), will go through the 47 Ohm resistor, and the LEDs will be wired up in parallel.

Then the + and – should connect to the appropriate wires in the middle of the LED string we made. This results in a Y shaped string of lights, with the accessory plug hanging from the middle of the string. Remember that the resistor is expected to get warm (perhaps quite warm) so dont use anything that will melt as part of insulating or anchoring it – hot glue would be a no-no.

A length of 2-conductor cable long enough to go around your cars interior. I made the one shown out of green and red (Christmas colors).

The lights are alternating red and green LEDs with a ping pong ball around each LED. They are bright enough to see well at night, but not so bright that they interfere with your vision or attention while driving. They can be turned off simply by unplugging the adapter from the cigarette lighter socket.

(From past experience these get attention when going through a drive-through.)

, secure the ball and the LED together (and cover any exposed wire and LED leads) with hot glue.

, select a spot for your first LED, separate the wires if required, and strip a piece of the two wires so that the conductors are exposed. You dont need to actually remove the insulation from the wires entirely – you should be able to just push them aside enough with a wire stripper so that you can solder the LED to the conductors.

How To MakeLEDIn-Car Christmas Lights

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