A cheap LED contoller, a variation

[dad]

Hi All
my second 'sabre has a simpler layout than my first, the switch that I am using is a prewired Chrome plated brass automotive switch, a little space saving, and a method of adjusting turn-on time/intensity. The circuit that I have used is a modification of my previous LED controller, with 2 main differences. There is a 'pot' or variable resistor to change startup time/intensity and I'm using a simple single pole switch, just on/off. (I'll more pics later)

the wiring layout is below.



R1 is 220R, RV1 is 1kR, C1 is 4700uF. I used an MJE2955 transistor just because I had one handy, you could still use an MJE3055 like the original circuit by making the voltage polarities the same as the original circuit.

The action of the circuit is to give a slow start-up and instant off, turning the 'pot' changes the start-up time and LED intensity.

Also in this layout I have used a U-channel heat sink that slides neatly into a standard MHS tube. Which brings me to a word of warning, the tab on the transistor and whatever you attach it too (the heatsink) is part of the circuit, so there is always a chance that a short ciruit may occur between an uninsulated battery terminal, the MHS tube and the heatsink/transistor. I also recommend testing the circuit and then covering the transistor, wire and connections with hot-melt glue for some mechanical strength.

the original post is here http://www.fx-sabers.com/forum/index.php?topic=22326.0

For those who are old enough to have worked with transistors, you could trade capactor size for a Darlington-pair, replacing the 3055/2955.