How to use a latching solenoid with a micro-controller?

Discussion in 'General Electronics Chat' started by solexious, Mar 3, 2010.

  1. solexious

    Thread Starter Active Member

    Nov 20, 2007
    55
    0
    Hello all,

    As a precursor to this question, I'm not asking for the solution to this, but for pokes and prods in the right direction of what I need to read up on to help me achieve this.

    I have this solenoid: https://www.rapidonline.com/product...ching+solenoids&moduleno=29538&catref=60-3250

    I want to control it from a micro-controller pin, when it goes from high to low a pulse of ~70ms should be sent down the positive connection of the solenoid and the negative connected to ground. And when going from low to high there should be a pulse sent in reverse. All this needs to be at 12v and the coil draws 5w.

    What should I look at? if it wasn't the need for just a pulse I would be grabbing reed relays to connect 12v to the coil, but needing to reverse the pins the pulse is sent down wont work with relays?

    Thank you in advance, let me know if I need to explain any part of this more clearly.

    Sol
     
  2. AlexR

    Well-Known Member

    Jan 16, 2008
    735
    54
    A google search on "H-bridge circuit" should provide you with some ideas.
     
    solexious likes this.
  3. solexious

    Thread Starter Active Member

    Nov 20, 2007
    55
    0
    The H-Bridge seems to be just what i'm looking for, thanks. Now, what should I be looking for to cause a pulse change of the state of my H-Bridge with the transition of my I/O pin?

    Thanks

    Sol
     
  4. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    If you use an H-Bridge like the LMD18200T or the LMD18201T then all you need to do is set the direction pin to either High or low, then supply a pulse to the PWM pin to activate the relay, reverse the logic of the DIR pin to change the polarity of the power going to relay then supply another pulse to the PWM to deactivate solenoid....

    You will only need 2 I/O's, 1 for the PWM pin (which is the enable pin for the H-Bridge, when this pin is HIGH it will activate the solenoid in either direction depending on logic state of the DIR pin.....) and 1 I/O for the DIR pin.



    B. Morse
     
  5. solexious

    Thread Starter Active Member

    Nov 20, 2007
    55
    0
    Those seem to be just what I need, but I will be using 4-5 solenoids, and at ~£14 a go those h-bridges will add up quite a bit :s

    Is there a cheaper way I could do this?

    Thanks for your help
     
  6. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
  7. AlexR

    Well-Known Member

    Jan 16, 2008
    735
    54
    Take a look at the L6201/L6202/L6203 chips (all the same function but different packages). They are somewhat cheaper then than the LMD18201 but will do the same job.
     
  8. John P

    AAC Fanatic!

    Oct 14, 2008
    1,634
    224
  9. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234
    to john P & Kmoffett:

    Those H-Bridges circuits are for solar robotics, very low power and based on motors that run on 1.5 volts or less, I doubt the op can use any of these for his needs.... making your own h-bridge circuit with discrete components is fine and good, but when you are a newbie, purchasing an H-Bridge will simplify things a bit more for his needs.... and cause less confusion in the long run....

    But since you mention making your own, here is a really simple one I used back in the 90's for controlling a 12 Volt DC motor up to 3 Amps.....

    Discrete H-Bridge 2.jpg


    And if anyone is interested, I have PCB's (double sided through hole design with plated through holes, solder mask and silkscreen) and all the components.... we do not use this anymore since we switched to he LMD18201T H-Bridge, so I have a lot of surplus components for these h-bridge motor control boards.....

    My .02
     
  10. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    The OP is trying to pulse latching solenoids, not drive a motor. The solenoids draw 400mA for ~70mS. The solar bot circuit I link to would handle the 12V solenoids if the 74HC14 were replaced CD4504 HEX TTL-CMOS level shifter. Four transistors, four resistors, and two gates per solenoid...pretty simple?

    Since the OP was concerned about the high price, a discreet solution is the cheap way to go...depending the their skill level, of course.

    You can have it quick, easy, and cheap...pick two! ;)

    Ken
     
  11. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234

    So my point is valid: the circuit as shown won't work :rolleyes:. But you failed to mention to the op that he would have to swap components for it to work as he needs it :cool:!!

    I would prefer cheap quick, and also working!:D
    B. Morse
     
  12. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    T'was an example, not a complete solution. ;)

    Ken
     
Loading...