working headlights?

[jacoballardtattoo]

I have not attempted it just yet but thought asking others would be a great start, I want to put some small LED lights into my 24th scale. I have done it in a 10th scale R/C which is pretty common but was thinking the same would work here. My plan without further advice is this, drill out the light buckets to fit the LED glue the light in the hole, place a small battery pack and switch hidden in the body somewhere out of sight. My question is this, what's the best way to make a small cheap battery pack and switch and the best way to glue in the lenses cleanly? Any suggestions are welcome, ps. All builds I plan to do are on a tight budget and I love scratch building so tips that do not lead me to pre built options are preferred.

Thank you

[disabled modeler]

I once made one with working head and taillights...I made a access panel in the gas tank where the battery was...I put a small switch in the gas tank that stuck out the bottom.

[Ace-Garageguy]

You can easily fabricate a battery box from styrene, with brass contacts epoxied in place. LEDs use very little current, so you can use a tiny battery. Check the current draw of the LEDs you want to use, and size your battery accordingly.

Ebay has LEDs from China very very cheap. I got 10 for less than $1 once. Some of them were bad, but you can't beat the price.

Ebay also has micro-switches. In a 30-second search, I just found a 2-pack of SPDT 3-pin, two-position slide-switches (smaller than a penny) for $4.25, including shipping. Or 50 micro toggle-switches (8mmX4mmX5mm) from China, for $6.99 including shipping. If that's too costly, just twist the wires together for "on", untwist for "off".

NOTE: There are many momentary-contact style switches much cheaper, but they won't stay "on" unless your finger is on them. Understand what you're buying.

LEDs also produce almost no heat. A PVA (polyvinyl acetate) white glue that dries clear, used by many modelers for gluing clear parts, lights, canopies on aircraft, etc. will work fine for gluing lenses "cleanly".

Edited January 20, 2015 by Ace-Garageguy

[jacoballardtattoo]

Okay wow, thanks for all the tips. The model I'm building right now is a VW bug so I'm thinking I will use the trunk for the battery compartment. I think I have a salvage switch from an old R/C helicopter I can use.i just need to find the right battery and figure out how to hinge the trunk lid to open and close.

[Ace-Garageguy]

And welcome to the forum, Jacob.

Here's a bunch of tips on making opening panels like doors and trunks... https://www.google.com/search?q=site%3Amodelcarsmag.com+opening+doors&oq=site%3Amodelcarsmag.com+opening+doors&aqs=chrome..69i57j69i58.5932j0j8&sourceid=chrome&es_sm=93&ie=UTF-8

Edited January 20, 2015 by Ace-Garageguy

[Casey]

http://www.modelcarsmag.com/forums/index.php?showtopic=39079&hl=

[Ace-Garageguy]

http://www.modelcarsmag.com/forums/index.php?showtopic=39079&hl=

That's great, but that big ol' 9v battery is massive overkill for LEDs which draw very little current.

5mm LEDs are available in quantities of 100 for $2.72 including shipping from China (!) that only take 2V to 3.4V forward voltage (depending on color) at 18-20mA.

You don't add the voltages of the LEDs. They should be wired in parallel, total system voltage still being 2-3.4 volts. Two AAA batteries in series will give you 2.5 to 3 volts with enough amperage to run a long time. (4 LEDs, roughly a couple of hours, depending...)

Edited January 20, 2015 by Ace-Garageguy

[SfanGoch]

You can also stop by your local newsstand/candy store/deli and pick up some butane lighters with built-in LED flashlights

for a buck each. Take the bottom cap off, pull out the the light and use the unit as the basis to wire and light your car. The unit (less than an inch long) consists of a plastic holder containing 3 LR41 button cells, contacts and a LED. This is small enough to be almost invisible (except for switch. You can use a micro DPDT push on/push off switch when installing it in the gas tank. Only the button needs to be visible) All you'll need to do is connect whatever LEDs you plan on using and add the micro DPDT push on/push off switch. Cheap, and it works.

[Ace-Garageguy]

Now THAT is slick !!

[SfanGoch]

Now THAT is slick !!

If you look around, you can also find lighters with red and blue SMDs which flash in an alternating pattern. Those can be used to wire up a lightbar on a model squad car.

[jacoballardtattoo]

Some amazing tips, thank you guys these are all very helpful.

[jacoballardtattoo]

Bill I just checked out the link you gave me on the hinges, thank you I found my answer there quickly.

[blunc]

the "coin" battery used on computer motherboards to keep the system settings is a 3v battery perfect for this application and you can also buy the socket for these batteries for around $2 at a Fry's or Radio shack.

The battery is a CR2032 and will fit easily on most areas of a 1/25 or 1/24 scale model.

you can even rob this from a dead computer motherboard if you can unsolder the battery holder without destroying it...it's mostly plastic.

Edited January 20, 2015 by blunc

[Ace-Garageguy]

You may find that the small "coin" batteries will not provide sufficient amperage to run multiple lights, or last very long in the LED application. Check the specs for available amperage-over-time from the battery you want to use, and determine the total system current draw with the number of LEDs you want to use before committing to a system design.

The typical loads the little coin batteries are designed for are about 1/100 the load of one LED lamp. Click link: http://data.energizer.com/PDFs/cr2032.pdf

The "simulated application test" shows a load of .19mA. Remember that the load of one LED (post #7, is around 19mA...or 100 times greater)

Here's the spec sheet for a typical AAA alkaline battery. Draw your own conclusions. http://data.energizer.com/PDFs/E92.pdf

Remember also that your power supply requirements will be quite different if you want your model to sit for hours at a show with the lights on, compared to what will be required to illuminate the LEDs for a few seconds at a time (for which the cigarette-lighter power supplies are designed).

Edited January 20, 2015 by Ace-Garageguy

[blunc]

Bill is quite correct with the info regarding the coin batteries, when I want them to run longer I use two coin batteries in parallel.

If you can use surface mount LED's your batteries should last longer depending on how long you have them on and how many are in the circuit.

[jacoballardtattoo]

Thank you all so much, right now I'm thinking the aaa route is my best bet I have them laying around I was thinking of sourcing my lights from a set of mini Christmas tree lights from the dollar store, they already run 2 AAA batteries as there power. I just need to know how to build the battery box and wire in the lights? The only wiring I know is on real cars.

[SfanGoch]

The only wiring I know is on real cars.

?!?

If that is the case, wiring a model should be a lead pipe cinch. The only difference is less wires in a model.

[Ace-Garageguy]

Here's a simple schematic, for a real car. DC circuitry is DC circuitry, whether real or model.

Delete the LS1 "dome light" and one of the switches. The "car battery" will of course be the AAA battery pack, or whatever you decide to use.

L1, L2, L3 and L4 are LEDs wired in parallel. Your LEDs may require resistors, or may have them already attached.

[jacoballardtattoo]

Thank you Bill, I chose to wait on the working headlights for now (this is my first real build and felt I should take smaller steps) but I will be doing it in the future and your diagram helps. It is what I am use to, I tend to over think many things and did so with this one.