Model Train Forum - the complete model train resource - View Single Post - Need all of your threads on HOW-TOs, etc
View Single Post
Old 11-15-2019, 03:18 PM   #142
traction fan
Station Master
traction fan's Avatar
Join Date: Oct 2014
Location: San Diego
Posts: 3,554
Scales Modeled: N
West Simple cheap LED tester

I use 3-volt, flat disc, watch batteries to test LEDs. The problem was that holding the leads to the battery was sometimes problematic, at best. This wasn't the case when testing a single 3mm or 5mm LED. Then I could simply fit the battery between the leads and squeeze a little. However, surface mount LEDs and circuits containing LEDs (ie. inside a lighted structure) were a very different story.
So, I made this simple gadget from a clothespin, two brass brads, some bits of wire, and two mini alligator clips. It works quite well. I drilled through the jaws of the clothespin then inserted the brads with their heads meeting inside the clothespin's jaws. I then soldered red(+) and black(-) wires to the brass brads, and cut off the excess length of the brads. I soldered the mini alligator clips to the other end of the red & black wire leads. For good measure, I painted the halves of the clothespin red and black so I could always be sure of polarity when inserting the battery. By the way, don't leave the battery in the clothespin when you're not using it. The leads have a nasty tendency to short to each other and deplete the battery. Also note that I did not include a resistor. With only three volts and limited on time, it's not really necessary to use a current limiting resistor, but you could easily add one if you want to.

Traction Fan

3v battery holder2.jpg

3v battery holder1.jpg

3v battery holder3.jpg
To Puget sound, Electrified!
traction fan is offline   Reply With Quote