variable reluctance sensor/speed switch
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? |
variable reluctance sensor/speed switch
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 www.QuickScoreRace.com "stocky" wrote in message ... 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? |
variable reluctance sensor/speed switch
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? "Larry" wrote in message om... "Dan Hollands" wrote in message . .. 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 www.QuickScoreRace.com "stocky" wrote in message ... 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? A schmitt trigger would be a good way you will set the on time (LED) and at high speed the trigger would be so fast that you may not see it and as you noted the input loading would be reduced. Hope it helps |
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