Interfacing Cortron Keypad...Has coil / magnet switches???

[[email protected]]

I have a keypad I would like to interface to another application. I
am having a hard time getting any kind of diagram on it so I took
apart one of the switches. Each switch has a tiny magnet that passes
through a coil, yet no reed switch.
It receives 24Vdc and I am wondering how the circuitry is set up to
detect the switches.
Has anyone ever worked with one of these Cortron keypads before?
thanks

 

[linnix]

I have a keypad I would like to interface to another application. I
am having a hard time getting any kind of diagram on it so I took
apart one of the switches. Each switch has a tiny magnet that passes
through a coil,

That would be a tiny EMF generator.

yet no reed switch.
It receives 24Vdc and I am wondering how the circuitry is set up to
detect the switches.

Should be some op amps somewhere.

 

[whit3rd]

I have a keypad....  Each switch has a tiny magnet that passes
through a coil, yet no reed switch.

Magnet switching can be done with a reed switch (but that's
expensive), or a Hall sensor, but it can also be done with
a saturating transformer core: the magnet saturates the core
and decouples two windings from each other. I've seen
a toroid with two staples (one turn windings) with a magnet
on the key plunger implementing such a switch.

It's possible to use a linear generator, setting a flip/flop on
(+) pulses and resetting it on (-) pulses, but this is unreliable
unless a nonlinear element (like a Wiegand wire) is part
of the magnetic circuit.