Westach 720-4a sensor

Greetings,

Has anyone seen or developed a characterization of this tach sensor?
It is a combined magnet/coil combo used to generate a pulse when a
bit of iron speeds past(Ampere's law). In my case, I have 6 steel AN5
bolt heads/revolution roughly 3/32" from the sensor head at roughly 1000
inches/sec max.

I'd like to know the expected output voltage and impedance so I can
compute the input resistor for a 4n25. I need to divide the output
pulse rate by 4 with a little TTL to get it into the frequency range for
my tachometer system.

Any advice?



Ira N224XS flying, but due for a little panel rework