29 Apr
2016
29 Apr
'16
1:16 p.m.
On Apr 29, 2016, at 4:10 PM, Bill Sudbrink
<wh.sudbrink at verizon.net> wrote:
Paul Koning wrote:
Ok, I figured that much. The problem/question is why there
are no Amp ratings on anything? Assuming the DC equation:
Watts = Amps X Volts
I want a constant current supply that "pushes" 0.41 Amps.
A little more googling reveals that the above supply is
rated "1.67A output". This seems to support the W=AV
theory. So, do I want a PS labeled "15 watt 36vdc",
regardless of how many bulbs I want to drive? You say
"within limits". What specification do I look for to
understand the limits?
15 watt 36 V is an odd spec for a device that needs constant current. What it seems to
translate to is 400 mA device current, 36 volt nominal operating voltage. That's
perhaps 10-12 LEDs in series, since each has a forward voltage around 3 volts, perhaps a
bit more.
If you have a supply rated for constant current operation, 36 volt or so, settable
current, you could use that, crank the current setting down to 400 mA. If it's a
fixed supply (36 volts 60 watts, i.e., 1.66 A) then that would not work.
paul
On Apr
29, 2016, at 3:32 PM, Bill Sudbrink <wh.sudbrink at verizon.net>
wrote:
... The "bulbs" are labeled:
15F18120-45 15 watt 36vdc constant current
I'd like to put four in a fixture and I'm trying to
understand what kind of driver I need and how to wire
it. I was thinking of using a Mean Well LPF-60D-36
like this:
http://www.ebay.com/itm/Mean-Well-LPF-60D-36-AC-DC-POWER-SUPPLY-
Dimmable-LED
-DRIVER-36V-60W-CLASS2-
/161857068172?hash=item25af6edc8c:g:9hQAAOSwA4dWHVn5
and wiring the "bulbs" in parallel to it. But after
realizing that I'm not completely sure what a "constant
current" power supply does and doing a little "googling"
I don't know if that's the right approach.
A constant current supply is one that delivers a constant
current to a varying load (within limits) just as a constant
voltage supply delivers a constant voltage to a varying load.