variable reluctance sensor/speed switch

[stocky]

I am building a speed switch around a LM2907, but want to add a "pulse" LED
that blinks every time the magnet goes past the senor....I'm having a mental
blank, i'm sure it's easy but can't think how to do it! Should I
capacitively couple the signal from the sensor, so it doesnt mess up the
signal goint to the '2907 and use something like a schmitt trigger to flash
the LED? I know the output amplitude from the sendor varies greatly with
speed, but I need the LED pulses to make it easy to setup. Ant suggestions?

 

[Dan Hollands]

It is not likely you can drive the LED directly from the sensor - you
probably need some type of high impedance device like a mosfet to go between
the sensor and the LED.

--
Dan Hollands
1104 State Road
Webster NY 14580
585-703-2963
[email protected]
www.QuickScoreRace.com

 

[stocky]

My next thought was do I put the output of the sensor into an opamp and
drive it to a fixed level square wave, then feed that to the LM2907 and the
schmitt trigger (maybe via a cap). That would get me around the varying
input levels. yes?