Automotive bulbs have two filaments, but when one blows, the whole thing is garbage. However the other filament is just fine, and there are uses like current sinks for DIY power supplies or simply low voltage light or testing who knows what. Using them is made easier with a socket, as they get hot and are fragile. Here I present a method of making a socket out of scraps of wood and wire. Note that actual automotive bulbs are used with a retention clamp, none is presented here but wood is a good place to start.
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Step 1: Gather Materials
For this project you will need the following materials:
- Scraps of wood, a 2x4 and some stripping wood.
- An automotive bulb with at least one working filament.
- Solid core wire 18 gauge or thicker, the kind used in houses (Romex, or 30 Amp wire) is a good choice.
- Wood screws x 2
- Drill and wee bits
- 12v DC Power Supply
- Digital Voltage Meter
Step 2: Cut Slots for 2 Blades of the Bulb
The top blade of the bulb will rest on the top edge of the scrap of 2x4. Use the bulb as a guild to cut two slots with a narrow kerf saw, I used a hacksaw. Then drill 4 holes, one in the middle of each slot cut (really the middle of where the blade will rest), and another hole a few millimeters to the outside to install the wire. The drill bit diameter should be slightly less than the diameter of the wire.
Step 3: Install Wire for Bottom 2 Blades.
Once you have the wire, strip enough for the depth of the wood plus some extra to curl the end and push into the second hole drilled a few millimeters away form the slot. Fold the wires down on the back of the wooden scrap to hold them in place for a test fitting of the bulb. Ensure the top blade is against the top of the wood and ensure the wires are making good contact with the blades. Adjust as necessary.
Step 4: Install Top Blade Slot.
Here is where another scrap of wood with the correct dimensions comes in handy. Since it is a small piece of wood, take care with the installation, drill pilot holes for the two wood screws, and another hole in the front to install the wire for the blade. Strip the wire with plenty of copper for installation and the blade contact. Fold and install as shown. The top scrap acts as a clamp for the bulb. Once installed, the user can torque the screws tighter to ensure the bulb remains in the socket, or adjust for desired friction. A stout wire staple to hold the wires in place completes the construction.
Step 5: Test It Out
Use a 12v (up to 13.5v) DC power supply and try out your automotive bulb. Please keep the following in mind:
- Keep the bulb eyeglasses clean. Any grease say from your fingers can create hot spots on the glass envelope causing it to shatter.
- These are high amperage devices, care should be taken with fuses, wire gauges and common sense.
- Wood is flammable so a short of any kind is a fire hazard.
There you have it, the cheap and ugly wooden socket.