Wednesday, February 19, 2020

Cap divider feeding a low votage lamp.

For the test I'll use a 15 Volt 80 ma lamp. With 120 VAC at 60 Hertz.
I made the little test board with 2 lamps. the caps are .5ufd so I used 3. Looking good.

One lamp has 12.7 volts.
25.14 Volts across both lamps.
I put a jumper across 1 lamp and have 13.2 volts across a single lamp.

A tip of the hat to thr DIT. It is a very useful circuit for someone who needs to reduce the voltage but has no transformer. The only draw back I see is being able to find the capacitor you need for a specific voltage / current requirement and you need to make sure the cap is rated for line voltage.
There is a ready supply of 50 volt caps but they will not work in this application.

The radio in the background has been in the dark for a long time. The pilot lamps were blown and I could not find replacements. That is not a problem any longer. I can put the 2 I'm testing in it.


The as built matches the circuit. One more thought. In the original we had a limiting resister. I am using the pilot lamp for the limiter. Using it with tubes the surge could be a problem without the limiter. The higher the current the more surge. A rule of thumb is inrush will be 8 to 10 times the run current. The inrush can last 15 - 20 seconds in a motor circuit. Just a little extra info.

1 comment:

  1. From DIT.
    Thanks for your efforts, I will be able to use some of your points in the Class paper....