Picaxe and miniature reed sensor

Discussion in 'Embedded Systems and Microcontrollers' started by Edmunds, Feb 3, 2013.

  1. Edmunds

    Thread Starter Active Member

    Sep 27, 2010
    Hi all,

    It's been a long time since my last post here :).

    I am designing a Picaxe system to control some special functions of a model car. I need to stop one of the motors at end switches, but real switches are not feasible given the size of the model and location. So I looked into reed sensors and I find some excellent (but expensive!) SMD style reed sensors - http://www.mouser.com/ds/2/262/Reed_Sensor_MMS_E-44277.pdf

    If you look at the spec, it suggests max life time of 10^7 switches @ 1.5V&15µA. Given the price, the complexity of installation and probably close to impossible exchange of the sensor, I would like to use it to its max lifetime if possible. Now, it will be switching nothing, but Picaxe input, of course, but I guess that means more like 3.6V and not 1.5V if I'm running Picaxe @ 3.6V LiPo cell.

    How would one go about calculating the right resistor in series to keep the voltage at 1.5V and the current at 15µA? Is it possible to limit both with some kind of minimalistic circuit - SMD components only?

    Thank you for your time,

  2. tubeguy

    Well-Known Member

    Nov 3, 2012
    Very tiny current capability. Might I suggest using a Hall effect sensor which is also a magnetic sensor/switch. Solid state with MCU compatible voltages
    and ma currents instead of ua.
  3. tubeguy

    Well-Known Member

    Nov 3, 2012