LED driver chips

Mutie

Enlightened
Joined
Dec 12, 2002
Messages
352
Location
Los Angeles
Driving off CMOS or transistors. Back in the early 80's I used 4017 decade counters with various support chips to drive flasher type circuits. This was ok with the crappy LEDs that were common back then. The newer ones just don't cut it for brightness and the problem appears to be that CMOS logic can only provide a max of 10 or 15ma. Are there any driver or other type chips that can be used before the LEDs to get the required 20 to 30ma needed for max brightness? I heard that TI had some but haven't been able to find info.

Similar to this is the circuit used in those
flashing visors. I took one apart and was using Radio Shack NPN 2916 or 2915 (I forget which) transistors. I also tried 2222s. At the time it was ok but the last few times I tried it was so dim that it was not acceptable. I've also used different combinations of resistors and capacitors in the r/c portion of the circuit so that I get weird flash rates. This affects the timing but not the brightness. Can anyone recommend the proper one so that I get some decent brightness?
 

jeff1500

Enlightened
Joined
Jul 9, 2001
Messages
417
These are the ones I've tried for continuous operation. Might be something useful there.
 
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