optical slot switch motor controller

Discussion in 'The Projects Forum' started by D4rr3n, Jul 4, 2014.

  1. D4rr3n

    Thread Starter New Member

    Jul 4, 2014
    3
    0
    Hello first post here, I'm looking for some help designing a basic circuit.

    I have a few high speed 40 000rmp slot car racing motors I purchased for this project the voltage rating is 9-15V. I don't know what the amperage is but guess mA (can see the motor below if it helps)

    http://www.mrrc.com/car-components/motors/motors/motor-s-can-speed40-mt-p540-40000upm/12v

    What I want to do is use an optical slot switch so that when the slot is covered the motor accelerates as full speed in one direction and when the slot is uncovered I want it to reverse polarity and accelerate in the other direction but with adjustable speed (0 to full speed).

    I have a basic understanding of physics, did some very basic electronics in high school but very rusty and need help.

    I want the circuit to be simple,small and robust....any ideas?
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,791
    1,103
    Simplest (in terms of fewest components) and smallest would probably be a micro-controller controlling an FET H-bridge which drives the motor.
     
  3. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    You could use a DPDT relay operated by the slot sensor, for the motor direction reversal.

    For the two speeds maybe some extra relay contacts switching in the speed controller? 4PDT relays are commonly available.
     
  4. D4rr3n

    Thread Starter New Member

    Jul 4, 2014
    3
    0
    Can you suggest a micro-controller that can do this job?
     
  5. D4rr3n

    Thread Starter New Member

    Jul 4, 2014
    3
    0
    I would prefer not to use a relay as fast switching would result in contact sparking. I was thinking I might need a simple circuit that reverses polarity with a slot switch as input. When the slot is covered the current could go straight to the motor but when it is uncovered it could be diverted through a speed controller/variable resistor then onwards to the motor.
     
  6. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,791
    1,103
    Almost any micro would do it; e.g. an 8-pin device such as a PIC12F675.
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,524
    2,369
    If you are reversing on the same track then what is to prevent the 'covered' hi speed opto from being re-activated, unless you have a programmed method that detects when reverse/controlled speed is switched and then program an ignore of the forward opto in the reverse direction.
    Also if immediately going from fwd to rev it may not be desirable without some kind of decel/accel rate ability.
    Max.
     
Loading...