Re: AC/DC supply vs. UL
Posted by Bert Hickman on 10/23/2007, 8:41 pm, in reply to "Re: AC/DC supply vs. UL"
: Thank you very much for the info. The mains that you're speaking
: of I'm assuming are the 120-277vac from facility input feed? or the high
: voltage DC that'll be coming out of the supply? If it's the AC input, then
: the same safety considerations would be the same for the 208-277vac for
: the metal halide light fixtures as well wouldn't it? I'm just curious if
: the concern is because of the high DC potential.
: My power supply layout includes a varistor across the AC input,
: C1(47uf/350v) and R1 (200k) have a time constant (calc) of about 10
: seconds and I measured 200v@5sec, 108v@10sec, 61v@15sec, 33v@20, 19v@25sec
: and at 30seconds the supply is under 10vdc. C2 is a 68pf. There is also a
: fuseable trace that's 35um thk x 4 mil wide and Imax. is .357a. and the
: supply board is potted in the box. Can you think of anything else?
: By the way anything new going on at your end?
: Thanks again!
I was referring to the input mains (and any other portion of the circuitry that has hazardous voltages), and the need to insure that there's no possibility of accidental contact under normal conditions. There may also be flammability and fault protection considerations that may apply.
The main fun thing going on here is that we're planning another production run to make Lichtenberg Figures in the middle of November. There's lots of planning and material preparation work going on, but actually making them is really quite a lot of fun (and a fair amount of work). We're really looking forward to it!