Hall effect sensors in series

I am wondering if it is possible to connect 2 A3144 sensors in series? I want to have it so that when 1 sensor senses the magnet and turns on then that allows the second sensor to turn on when it sees the magnet and completes the circuit to light my bulb. I tried connecting leg 3 out of #1 sensor to leg #1 in of the second sensor but when I do that the circuit is constantly on, how can I make it start with #1, flow to #2 then the circuit is complete and lights the bulb and when #2 loses the magnetic field the circuit shuts off and is ready to see the next magnet on the wheel? The two sensors are situated a few degrees off from each other.


A few points:

  • The A3144 is obsolete, suggested replacement being the A1104
  • The output of these sensors is an open-collector format, hence one must think in terms of switching the low or “ground” side of any connected loads.
  • Maximum output current of the sensor is 25mA, supply current ranges from 4~9mA; if attempting to use one to control another by virtue of switching its power supply, this leaves a maximum of 21mA available, which is generally less than needed to operate most things a person typically would refer to as a “bulb.”
  • A more “proper” approach would be to use a NOR gate to perform a logical AND function in context of the inverting-output logic presented by these sensors. The resulting positive-logic output could be used as such directly, or potentially used to drive an N-channel FET which would again function as a low-side switch.

Thank you for your input!

I should have told you that I am using a couple of FET’s to supply my load

I just thought that there may be a way to make these work as an AND function together to supply my FET’s.

I think this would provide a pure AND function.

Although reading your description it seems like you might not want a #1 off transition to turn off the load (which is not pure AND).