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using lm3916 to drive bigger currents than single leds

 
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glassfin
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Joined: 01 Mar 2009
Posts: 3

PostPosted: Sun Mar 01, 2009 4:26 pm    Post subject: using lm3916 to drive bigger currents than single leds Reply with quote

I'm building vu meters out of some lm3916's, and i'm wondering what would be the least components involving way to use a lm3916 to control larger led arrays, I'm quite sure that if I just put a bunch of leds parellel it'll be more current than the ic can handle.

I think it would need some transistors, but not yet sure of exactly how to wire them either. I'll need to rig a comparator circuit that would trigger for example a mosfet or such? on each led "output"(input.. gah). been a while since my electronics courses.

oh and the least delay too, would be preferable, no slow relays please.

schematic for the lm3916 ic is at
http://www.national.com/mpf/LM/LM3916.html so you can see the basic schematic for using it.

any ideas, help?
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glassfin
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Joined: 01 Mar 2009
Posts: 3

PostPosted: Tue Mar 03, 2009 4:56 am    Post subject: Reply with quote

ok I got the first prototype soldered yesterday from those 3916's, pretty bright. still thinking of the best(least components and fastest, don't care about component price too much) way to control things from it's inputs.

also up on the table is now finding and building a mic boost circuit for it.
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Alexander125
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Joined: 13 Jan 2009
Posts: 105
Location: Galati, Romania

PostPosted: Wed Mar 04, 2009 12:22 pm    Post subject: Reply with quote

use som IRF350 mosfets.
They can carry a lot of current.
Oh and add some heatsinks.
Or you could use the ULN2803 or 2003 to power the FET-s
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glassfin
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Joined: 01 Mar 2009
Posts: 3

PostPosted: Thu Mar 05, 2009 2:36 am    Post subject: Reply with quote

thanks for the tips, overall i'm pretty impressed with the lm3916's, should've run into them a long time ago.. Smile. I'll need a mic boost though at this point as well, oh well, a fun project to (re)learn some stuff.

besides just going extra large, my other goal is to build a minimalistic miniatyre version with built in mic. a bit bigger than a matchbox should be doable(but slow to do..).
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