Instructables

Flashlight Bulb Socket for EXPERIMENTS

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...
 
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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.
doo da do1 year ago
If you get a wide rubberband that will hold the wires on the battery. It worked for me.
eyerobot4 years ago
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.
Why are you not just using LED's?!?
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.
westfw (author)  The_pyrogeek6 years ago
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.
Sandisk1duo5 years ago
just solder wires on, and encase in hot glue!
lemonie6 years ago
I like that you use 'tongue depressors' over lollipop/popsicle/ice-cream sticks. You are a doctor? L
westfw (author)  lemonie6 years ago
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.)
you can find them at a craft store
lemonie westfw6 years ago
OK. Where do you get your 'tongue depressors' from? L
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
VIRON lemonie6 years ago
craft stores, dollar stores, or the doctor's office
knex lover6 years ago
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.
russ_hensel6 years ago
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.
westfw (author) 6 years ago
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.
awoodcarver6 years ago
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
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