Help me control a linear actuator with a switch and RFID sensor. Total Novice alert!

Discussion in 'The Projects Forum' started by Emilio84, Sep 18, 2013.

  1. Emilio84

    Thread Starter New Member

    Sep 18, 2013
    Hey everyone. I'm working on a surprise for my girlfriend. This purpose of this circuit will be to drive a linear actuator (for a TV lift) which will be activated via a rocker switch a RFID sensor which acts as a switch as well.

    The actuator is a 12v unit from Firgelliauto. The unit has a built in limit switch and relies on the polarity being reversed to go from lifting to lowering and vice versa. I do not need to stop the unit at any point, I need full extension and full retraction.

    I'm not sure what stroke I will use but it will most likely be this unit:

    The RFID sensor is this unit which basically acts as a switch that closes the circuit when the RFID tag is read by the sensor. This unit will keep the current flowing as long as the tag is present. Based on the location of the sensor the tag may be present for long periods of time. I want to be sure that won't cause damage/overheating/etc. The seller told me that I should be using a reed relay as a standard relay may burn the unit out as the coil will have too high of a current draw. He recommended a 20ma reed relay. Help?

    I was thinking of using the circuit shown here but I'm both not sure how to integrate the RFID unit into the mix as well as what exactly I'm looking at.

    I'm sorry I'm not more helpful but this is my first project of this type. The desire with the RFID sensor is to have an RFID tag hidden in an object that can be placed ontop of the cabinet the TV is mounted in causing the tv to lift or retract when the object is put down and then when the object is removed and replaced it will do the opposite (extend or retract respectively). This would be in conjunction to an additional hidden toggle switch (momentary or sustaining.. doesn't really matter to me as long as it is a single press to have the actuator extend or contract completely).
  2. Emilio84

    Thread Starter New Member

    Sep 18, 2013
    Anyone? If I need to supply more information I'm happy to, just let me know what is lacking.
  3. strantor

    AAC Fanatic!

    Oct 3, 2010
    I don't recommend those circuits you linked to; they require 2 seperate signals. I recommend using a single SPDT relay that retracts the actuator when no power is applied, and extends it when power IS applied.

    I don't see the current output rating for the RFID unit, but i guess it's low. I would send that signal to a MOSFET, and let the MOSFET switch the relay.

    Other than that, seems pretty simple.

    refer to drawing below, ignore Q2 (just go straight to GND).