Flashlight Bulb Socket for EXPERIMENTS




Introduction: Flashlight Bulb Socket for EXPERIMENTS

About: Middle aged geek username also works at yahoo.com, mac.com, comcast.net, wharton-10.arpa

Flashlight bulbs are common, easy to find, and inexpensive (especially in bulk), but they are a pain in the neck to attach wires to, which somewhat limits their use in assorted hobby projects, especially when children are involved.

The picture shows a "socket" that will hold a normal "flanged" flashlight bulb (somewhat) securely in contacts with normal wire. I'll try to get more "process" pictures if I can find my tongue depressors, but the finished-product photo should show most of what you need to know...

Step 1: The Issues!

Here's a picture of a flashlight bulb. In a typical "real" socket, a spring of some kind will push one connection into contact with the nipple on the bottom, while simultaneously pushing the flange against the second contact. Thus both connections are under tension and will make good, reliable connections.

Traditionally, one wraps a wire a couple time around the base, which works "ok", and then uses tape to hold the nipple against the end of a battery, which works NOT so well.

Springs are good, but generally hard to find in whatever size you actually need. "Springy" metal tends to be difficult to work with. You can solder wire to the nipple, but that's a pain, not really that reliable, makes the bulb non-replacable, and isn't appropriate for younger children.

Step 2: The Socket

You'll need a tongue depressor, a rubber band, and some solid wire. The wire here is from cat5 ethernet cables, which get thrown out by the cartload cause they're too expensive to have a highly paid networking engineer untangle them after they've been used once. (grr.)

So, you take your tongue depressor and cut it in half. Near the end of one half, drill a hole that the glass part of the bulb will fit through, but not the flange (typically, this will be between 3/8 and 7/16 inch.)

At the end of the other side, put a couple notches to hold the wire in place and wrap one wire around at least twice.

Wrap the other piece of wire around the bottom of the glass bulb, just above the flange, and twist it onto itself so it stays.

Stick the bulb through the hole in the T.D. so that it pushes the wire into contact with the flange. Position the other half of the TD so that the bulbs nipple is wedged between the loops of wire. Secure the pieces together with the rubber band, which provides spring-like tension.

Ta Da! Done!

I figure a teacher or instructor or parent with access to tools like a "clamp" and a "drill press" could cut and drill a couple of hundred of these in an hour for minimal cost. Go slow drilling the tongue depressor; they're thin and weak and tend to split. I bet a LASER CUTTER could do the job really well!



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    17 Discussions

    If you get a wide rubberband that will hold the wires on the battery. It worked for me.

    I can't count the number of hours i spent as a kid, Trying to find ways to mount flash light bulbs for experiments.
    Usually it ended with me wrapping the wire around the bulb, And trying fruitlessly to solder to the positive terminal, Until I finally came up with a solution similar to yours, Only I used two pieces of sheet metal touching the flange, And positive terminal, Separated with wood or plastic.

    Your solution is nice for a households products point of view, And very handy for school projects.
    I only wish I had something like it when I was in school.
    Nice job.

    This response is a few years late but someone else might be looking for flashlight bulb sockets as I was.

    One of the main reasons one uses a light bulb instead of an LED is that light bulbs are resistors and can act as a poor-man's voltmeter, i.e. higher voltage = brighter light. Yes the resistance does change with temperature but over the normal operating range, current is proportional to applied voltage and vice-versa.

    LEDs are forward-biased diodes. The voltage drop is relatively constant. The problem is, a small change in voltage, e.g. 0.1V, will result in a very large change in current and hence light output. This is why resistors are placed in series with LEDs -- to limit the current. (Interesting experiment: graph voltage drop and current flow. What function best fits the curve?)

    OTOH, if you have a current source, i.e. the current is constant regardless of voltage drop, LEDs work very well. Light output is directly proportional to current over a very wide range.

    Interesting fact: the energy (wavelength) of the emitted photons is approximately equal to the voltage drop. (Not so surprising, actually. Where do you think the energy in each electron goes as it passes through the LED?)

    As for attaching wires to bulbs and LEDs, I taught my students to solder. We have a number of solder stations in our "science and technology center" that the students are free to use on their projects.

    LED add a level of complexity inappropriate to elementary school students (ie "polarity"), and generally are a fraction of the brightness of an incandescent flashlight bulb of equal cost. (and come to think of it, there isn't really a good way to attach wires to LEDs, either. I'm not sure "twist the wire around the LED lead counts as "good.")

    you can wrap 24 gauge solid wire around the leads with pliers to get an OK connection.

    I like that you use 'tongue depressors' over lollipop/popsicle/ice-cream sticks. You are a doctor? L

    5 replies

    They're different. A "tongue depressor" is about an inch wide, while a popsicle stick is only about 1 cm wide. Since the hole will be about 1cm, you have to have the wider sticks. (I am not a doctor. I'm a software engineer.)

    if your in the usa try wal mart or walgreens or something like that, craft stores like michaels.. stuff like that im guessing. or pay a friendly visit to your doctor and demand some tongue depressors haha

    LED's may be more expensive but they dont use as much power as incandescent bulbs so if you a battery you'll get more light out of that. LED's are also the amount of same brightness as incandescent bulbs(depending on the size you have)and are waterproof and they last 100x longer than incandescent bulbs. An good axample is that when you drop a incandescent bulb from five feet it will most likely break, but if you drop an LED from 30 or more feet it will stil work as LED's ar made with plastic not glass.

    When I want small bulbs I cut up christmass tree lights. Typically run on about 5 volts, come with socket and wires. Seem to tollerate over voltage pretty well. One string of lights gives you a lot of bulbs. Can get them in color or not. Because of the wide voltage range work in serial and parallel pretty well. Unlike led's you do not need a series resistor.

    Discount School Supplies has "Wood Craft Sticks" in 4 different sizes:
    1) mini: 1/4 x 3 inches
    2) regular: 3/8 x 4
    3) Large: 3/4 x 6 (I believe this is the size I called "tongue depressors")
    4) Jumbo: 1 x 8

    300 of each will cost you about $16, including shipping.

    Craft shops sell them by the bag full as craft sticks or something like that, right next to the popsicle sticks listed as small craft sticks , very nice use of light bulb and tongue depressors