NNTP-Posting-Date: Sun, 06 Oct 2002 01:33:07 CDT
Newsgroups: sci.electronics.components, sci.electronics.design, alt.engineering.electrical, aus.electronics, sci.electronics.repair
Subject: Re: Best way to power array of LEDs?
Date: Sat, 5 Oct 2002 23:33:02 -0700
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You sure have gotten a lot of replies/suggestions on your LED project. In my
monthly EE Product News catalog, I came across a display ad from Supertex
Inc for the HV9904 and HV9906 Flex Switch. These are advertised as taking a
rectified AC or a DC input of 10V to 400V and being able to power "hundreds
of LEDs". In fact, one of their sample circuits in the HV9906 datasheet is
stated as providing a 0.5A constant average current output to power up to
249 LEDs, each operating at 20mA to form a large LED lamp or array.They are
using matched 2N2222 transistors or NPN bipolar transistor arrays to feed
the LED strings. Here's the online link to their datasheet.
I've already ordered some samples of the 9906 to test with some prototype
Hope this might help.
Vince Kluge, Sr Engr
Palo Verde Nuclear Power Project
"DaveC" wrote in message
> Have assembled an array of LEDs for use as a 3rd brake light in my car,
> configured as 4 rows of 9 jumbo LEDs, as of yet unwired. Of course the
> supply will be 12 volts nominal (13.8 volts, maximum).
> My options, as I see them, are:
> 1) Wire individual resistors to each LED based on its operating current
> 2) Wire each row in parallel and connect one resistor based on operating
> current for 9 LEDs
> 3) Install voltage regulator to output voltage (ie, 1.3 volts?) to operate
> all LEDs in parallel.
> What is the best method to power these from an intermittent (whenever I
> the brake pedal) power source?
> Other options for powering this array?
> Note that my return address is corrupted in an attempt to reduce spam. If
> choose to e-mail me, please correct my address as described below.
> Dave Carpenter
> Sound Logic
> Remove the numbers to reply via e-mail