A LED test lamp is a very handy device to have. It allows you to test whether a DC voltage exists anywhere in a circuit. It is ideal for automotive trouble shooting where we have 12 volt circuits. Just clip the alligator clip to the body earth and put the probe on to any part you want to determine is live. The LED test lamp has numerous applications.
I've even seen probes of LED test lamps which were needle point so that you could penetrate the insulation of wiring for test purposes.
BTW LED stands for light emitting diode.
The easiest way to house a LED test lamp is to build it into a discarded pen case as depicted in figure 1 below.
Figure 1 - diagram circuit of a led test lamp
To build your LED test lamp you will need:
Personally I'd make the durable hookup wire running to the alligator clip of your LED test lamp about 2' or 600 mm long to give you a bit of flexibility.
Here you are pretty much on your own because it depends entirely upon what you can scavenge or have available. Pen cases are common, I'd try for a transparent one. Wire should surely be capable of being salvaged from discarded consumer equipment. The same might apply to your 560 ohm resistor and the LED.
If you don't know what a 560 ohm resistor colour code looks like, then go to my Resistor Colour Code Page.
Remember, for a new shop bought LED, the anode is the longer lead. For a salvaged one your on your own. If you're not familiar with soldering then here's a page on the topic of soldering.
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Created 7th March, 2002
Updated 8th March, 2002