Shift light?

[Frederic Breitwieser]

> Man, I'm glad somebody got it.  I was beginning to wonder.  Thanks.

I dunno... thought it was pretty obvious myself :)

The easiest way to do a shift light homebrew circuit is with a 555
timer, and have it set for a missing pulse detector.  Invert the output
with a transistor, and turn the life on when the pulses are found, not
lost.  THis is your approximate shift point.  Tuning R & C is not that
tough either... Forest Mims III has many books with this schematic in
it, all available from Radio Shack.

6000 RPM shift point.
V8 engine. 4 fires per rotation.  (every other stroke is the power cycle
per cylinder).
Tap off 12V side of diff, 4 pulses per rotation.
4 * 6000 = 24000 pulses per minute
divide by 60 (seconds in a minute)
4000 hz is the shift point frequency, if my math is even close.  

When your circuit hits 4000 HZ on the input, fire off an LED.  Can also
use a LM9400V if they still exist, its a V to freq and a freq to V
converter, in a single chip.  Use a op-amp afterwards (freq in, V out to
the op amp) and adjust with a variable resistor.

Many ways to skin this problem.


-- 

Frederic Breitwieser
Xephic Technology
769 Sylvan Ave #9
Bridgeport CT 06606

Tele: (203) 372-2707
 Fax: (603) 372-1147
Web: http://xephic.dynip.com/
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