In a message dated 4/16/2000 7:31:37 PM,
evening@... writes:
>I need to make a circuit that will take an audio click and give me a
>flashing led∗. I imagine that it's some kind of amplifier but beyond that
>I'm lost. Hopefully this will be fairly simple.
>
>Considering how much everyone loves LED's on this list I figured that this
>would be a good place to start.
>
>peace,
>
>John W
>
>∗preferably something that will fit into a small project box and run on
>battery power
There is a good basic circuit for a LED circuit (labeled LED Driver) on page
341 of the 2nd edition of Walter Jung's "IC Op-amp Cookbook." It uses 5V,
however, I've used the same one (Serge used it too) with slightly different
resistors values for 12V and 15V PSUs. I'm not sure batteries are the best
way to go for this one since (as Paul said) LEDs are current hogs. The
circuit assumes you're getting your input from an op-amp output.
As I recall, Steve posted the basic circuit to the list about a year ago. I
can look it up tomorrow if you want. It just uses 2 (3?) resistors, a diode,
an NPN transistor, and ground +V and the output wires -- oh, an LED of course.
JB