Modding Questions - :help:

Neg2LED · Jul 20, 2004

Hello,
i have a bunch of white LEDs, and i want to run 3 of them in paralell, pushing about half a watt (150ma) through them (collectivley, of course) from 2 123As. i need a simple buck regulator, and here comes my requests:

1. does anyone have a circuit diagram for a simple transistor buck regulator that i can use to run my 3 LEDs in paralell at 150ma from a 6 volt source, and;

2. what could i use for a body? i want to use some copper tube, but what about tailcap? i could solder the tail cap on, but for the head i need something that will screw on. help!

keep in mind that i dont have access to a lathe, and would rather not have something cnc machined by a metalworks place - too many $$$...

neg

Doug Owen · Jul 20, 2004

[ QUOTE ]
Neg2LED said:
1. does anyone have a circuit diagram for a simple transistor buck regulator that i can use to run my 3 LEDs in paralell at 150ma from a 6 volt source, and;

2. what could i use for a body? i want to use some copper tube, but what about tailcap? i could solder the tail cap on, but for the head i need something that will screw on. help!

[/ QUOTE ]

You know how the saying goes, "simple, cheap, efficient; pick any two...". To me it makes some sense that if this magic circuit (the one everyone keeps asking for) actually existed it wouldn't be such a big secret. That is, lots of folks in the know would be using it rather than the more expensive and complex compromises we see.

As far as retaining the end cap, why not cut a sloping slot on the end to mate up with a short pin you solder into a hole drilled in the bottom end of the tube. The end cap would then 'twist on'.

Doug Owen

idleprocess · Jul 20, 2004

Hm... in mechnical design they want it perfect, cheap, and now, but it's only possible to satisfy 2 of the three usual demands. Ultimately, it costs time, money, or reliability.

I'd think that a basic current supply IC would work fine, but I can't begin to speculate on their efficiency.

Neg2LED · Jul 21, 2004

i want it simple and cheap - i was thinking like this: use Doug Owen's idea for attaching the head and tailcap, and ill make the tailcap from copper pipe and copper rod, and the head from some more copper pipe, and two small bits of copper rod.

neg