Automatic Timed Polarity Switch and Shutoff

Discussion in 'The Projects Forum' started by Josh Kompa, Mar 24, 2015.

  1. Josh Kompa

    Thread Starter New Member

    Mar 24, 2015
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    0
    First off thank you to anyone who is able to point me in the right direction. I am a mechanical guy and have confused myself trying to dig into circuit development.

    I am looking to keep the circuit as simple as possible. I will be powering system using a wall adapter for 110V AC however I have found wall adapters to convert this to 6V DC for me which I will use in order to simplify my circuit unless someone lets me know a reason not to. The 6V DC is what is specified for the two components I am trying to run, a Micro Stepper Motor and a UV Light.

    My system needs are as follows:
    - External Contact Switch
    - Used to connect the system (like a button to turn on)
    - this contact will be separated and reapplied manually to start cycle again when need be
    - System needs to run for 60 seconds and then turn off automatically
    - Micro Stepper Motor (specs 6V DC and 200mA (assuming this is start-up amps) down to 20mA (assuming this is continuous running amps)
    - Run oscillating while system is on as stated by the external contact switch above (60 seconds)
    - approximately 6 seconds forward followed by 6 seconds reverse
    - exact time isn't necessary but looking to have approximately 5 full cycles for the 60 seconds run time
    - UV Light (specs indicate 6V DC and 6mA)
    - Run continuously while system is is on as started by the external contact switch above (60 seconds)​

    I believe I am going to need a 555 timer, possibly 2. One to control the total time till shutoff and one to control the time to polarity switch on the motor which I also believe would require an H-bridge to switch the polarity. All of the samples I have seen show additional resistors, etc. which I am uncertain what are for and seem to be over complicating the circuit, so that probably just shows how clueless I am. Also I am thinking that polarity switch for the motor may negatively affect the light so does that mean I need another switch for polarity at the light?

    Comments to point me in the right direction or a sample circuit diagram would be greatly appreciated.

    Thanks again.
     
  2. Reloadron

    Active Member

    Jan 15, 2015
    966
    232
    Would this be a 4 wire stepper motor and do you have a link to the stepper motor data sheet?

    The reason I ask is before you start buying parts and soldering components there may be some very easy ways to go about this using an Arduino (or like similar) micro-controller and some easy code samples. An Arduino Uno for example runs about $26 USD and a motor shield (if its even needed) is about $15 USD.

    Ron
     
  3. Josh Kompa

    Thread Starter New Member

    Mar 24, 2015
    3
    0
  4. Reloadron

    Active Member

    Jan 15, 2015
    966
    232
    High Quality 3v 6v 9v 12mm micro metal dc gear motor for electric door lock. The motor you linked to is not a stepper motor, it looks to be a plain everyday two wire DC gear motor, not a Micro Stepper Motor. For direction reversal I would just use a basic H Bridge module. Start with a H Bridge chip like this one . Then to keep things small the timing and control could be done using a small 4 pin uC (Micro-Controller) if you have someone who could write your programming code. Regardless I don't see the motor you linked to as a stepper motor so if you require a stepper motor I don't believe that is it.

    Ron
     
  5. Josh Kompa

    Thread Starter New Member

    Mar 24, 2015
    3
    0
    Ron, you are correct this is just a DC gear motor. Sorry about the confusion, I was looking at stepper but not necessary for my project.

    I am not familiar with the micro-controller. I am assuming this could handle the 2 timed switches, first to switch direction through the H-bridge and second to ultimately shut off the system? Would I need 2 H-bridges in order to allow for direction reversal of the motor but keeping proper polarity on the light?
     
  6. Reloadron

    Active Member

    Jan 15, 2015
    966
    232
    Just a single H Bridge should work fine. When it comes to motor direction it is just a matter in most cases of placing a slight delay in so you get Forward (Delay 500) Reverse. Most motors don't like going forward to reverse directly so you give the motor maybe 1/2 second or so. I am not a programmer type but have dabbled in programming. If I had to depend on my programming skills before I retired I would have starved to death. :)

    Here is what I suggest you do. Using a sharp pencil and a clean blank sheet of paper write down the exact sequence you want the motor to follow. That includes an initial button push, then all the timing step by step. Any number of uC chips can be programmed to do what you want to do. The uC sends signals to the H Bridge. As to an H Bridge there are very small modules out there which are plug and play saving you building the H Bridge.

    This is how I would likely go about doing this. Hopefully other forum members will share some thoughts. If you go the uC route this forum has some members and a section for just such projects.

    Ron
     
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