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Sunday, 13 December 2015

Apparatus for the Testing of Christmas Tree Light Bulbs

Apparatus for the testing of Christmas-tree light bulbs. I got very frustrated trying to test Christmas-tree light bulbs using a multimeter. Almost impossible to hold the probes on the little wires. I thought about making some kind of bulb-holder, but then hit upon this idea, using a wooden clothes peg. 

Copper tape is wrapped around the ends of the arms and secured with a soldered joint on the outside of the peg. Wires are attached and connected to a battery which can be conveniently carried in a pocket.

The peg is clipped across each bulb as it is removed from the chain. The battery should be chosen appropriate to the Voltage rating of the bulbs - mine are 2.4V - so a part-used "C" cell makes the bulb glow dimly, Note small screw positioned between arms of peg to prevent it closing fully, this is important as it prevents the battery being shorted when no bulb is present

Even though it was dark by the time I had finished it, I was still able to get the set working. The wires on some of the bulbs had become tarnished and so there were multiple"failures" within each series string of bulb. The tarnish seems to be due to age rather than moisture as the new bulbs in the pack had also gone the same way. Happily a little scraping with a craft knife soon got them going again.

Happy Christmas and 73 to you all.
Hugh M0WYE


  1. This is really innovative. Thanks for posting this friend. I am sure it will be useful to a lot of people. Much Regards.

  2. This is a good idea of using wooden clth peg for making assembling and testing light bulb it is cost effective also and easy to carry out. i will try this.