School science/Bulb holder - eMyTextBooks

School science/Bulb holder

A bulb holder is a simple device for holding 3.5V bulbs for use in school laboratories. A cost-effective way of making bulb units to use with 4mm leads, follows.

See also: Constructing school science lab equipment/Cell holder

Equipment Required (to Make 60 Bulb Holders)

• 60 pieces of wood at least 120mm x 36mm and 20mm thick
• plastic bulb holders to hold MES bulbs (available from most Design & Technology suppliers)
• 4mm terminals, 60 black and 60 red (available from most electrical component retailers)
• small screws to fit through the bulb holders
• Extra flexible lead wire, black and red
• Solder + soldering iron
• Pliers
• Screwdriver
• Drills 7.5mm, 5mm & 3mm
• Countersink drill bit
• Solder Flux

Method for making the bulb holders

1. Get the wood cut the wood to the correct size and sanded if need be.
2. Drill 2 x 7.5mm holes at either end as show in fig 1.
   
3. Drill 2 x 5 mm holes near those.
4. Countersink the larger holes to about half way, so that you can attach the nut of the 4mm terminals.
5. Insert the 4mm terminals in the larger holes, one of each colour in either end, and secure with nut.
6. Attach the plastic bulb holder with the 2 screws, first drilling holes.
7. Cut a 6cm piece of each wire, strip the ends and solder onto the tags on the plastic bulb holder. Ensure you have got red wire to the red terminal and black wire going to the black terminal. Then push the wire through the 5mm hole and out the other side so you can then solder it onto the 4mm terminal.
8. It should look something like this. see fig 2. these are usually very durable and can be used in conjuction with cell holders etc.