Re: Musical LED's
- From: et472@xxxxxxxxxxxxxxxxxxx (Michael Black)
- Date: 30 May 2006 16:22:42 GMT
"Rob" (blingcity101@xxxxxxxxx) writes:
I'm in a third-world country and have limited resources. I want to beI don't have anything specific, but it is doable. Using ICs to
able to create a "sound meter" out of 8 or 10 LED's which could be
connected to the amplified line that leads to the speakers. The only
electronic parts I have are wires, capacitors, LED's and transistors. I
have used capacitors and transistors before for my woofers and
tweeters, but now I want it all to look good. Any suggestions?
---P.S. This is my first day and first post.
drive the LEDs simply makes it more compact.
The basic idea is to rectify the incoming audio signal, and then
feed that varying DC voltage into a string of voltage comparators.
When the audio signal goes above the trip point of a comparator, the
LED on the output goes on. If the audio goes up further, then the
next higher comparator goes on, and so on. (Some of the ICs may
add to this, with locking mechanism so only one LED is on at a time.)
You can make comparators with transistors. I suppose you could even
get away with a single transistor per comparator, doing something like
a positive voltage on the emitter so the input voltage has to rise
above that trigger voltage, but it probably is better to use a couple of
transistors per comparator. This sort of circuit used to be common before
ICs became common.
Maybe someone else has something specific. Old books likely have this
sort of thing, too.
Michael
.
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