On 3 Aug 2012 01:12:23 GMT, the renowned "DoN. Nichols"
wrote:

On 2012-08-02, Spehro Pefhany wrote:
On Thu, 2 Aug 2012 09:27:45 -0700, the renowned "Steve B"
wrote:

I have some LED pole lights coming for my boat. They are for inside the
boat for when we are fishing, and want a dim light. They come hard wired.
Could I put them on a rheostat so that I could dim them down?

Steve


Buy an electronic control from China on eBay. Costs just about
nothing.

But he wants to run it from DC on the boat, not 60 Hz AC, so I
think that the light dimmers (if that is what you are suggesting) won't
work without first converting to AC.

Enjoy,
DoN.

Just as a follow-up, I bought one and it's made pretty well. The
design uses an 80A MOSFET and a PWM made with a comparator and 555
generating sawtooth waves. Drive to the mosfet gate is quite pokey
(microseconds rise/fall), so I imagine RFI would be minimal (no RFI
filtering). I would derate it a bit at 24V because of the switching
losses.

Protection against input reversal (series diode), but no protection
against short circuit on the output or applying reverse voltage to the
output (either will destroy the unit almost instantly). No low voltage
lockout either- don't know if it could die from that or not (eg. run
battery down slowly and the MOSFET should go ohmic at some point). No
instructions at all.


Best regards,
Spehro Pefhany
--
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