DC motor with timed auto reverse, continuous loop when on

Discussion in 'The Projects Forum' started by CFGraham, Feb 4, 2015.

  1. CFGraham

    Thread Starter New Member

    Feb 4, 2015
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    Apologies if this is tired topic, but I have been searching around for months and haven't been able to locate a similar setup. I have a DIY project that is similar to a rock tumbler. I'd like to automate the control of it with continuously-looping reversing motor cycles when it's switched on. Currently, the motor direction is controlled manually by a simple motor controller board with a potentiometer to control speed and a 3-way rocker switch to control direction. I'd like for the motor to automatically reverse directions every few revolutions of the tumbler drum for as long as the unit is switched on. Ideally, the delay time would be controlled with a separate potentiometer, but don't know if that's practical with my limited skillset. I have no electrical background, so this may be too complicated for me to take on, but was really hoping there might be a ready-made board out there somewhere that would work for this project.

    An Arduino board/motor driver combo seems the obvious choice but I'd like to avoid something that needs to be programmed. It's important to control both motor speed and delay on demand. The drum is for developing film in, and reversal is important for even development, and the motor's cycles will likely need adjustment between batches depending on the film type, contrast, etc. Right now I'm just reversing the motor manually with the switch, but it's a little tedious, and probably hard on the components.

    The motor itself is a power seat motor, 12VDC with a 1.5A no-load current, and I think it has a 25A stall current. The film drum it is about 8" in diameter but a capacity of only 1 liter of solution, so there isn't a lot of load on the motor (except when I accidentally switch directions without letting the motor come to a stop).

    Thanks in advance for any ideas or suggestions. Even suggestions for proper search parameters would be enormously helpful. I can never seem to string together the correct keywords.

    BTW, there's a video of the setup here-
     
    Last edited: Feb 4, 2015
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    So you want to control speed, direction and cycle time. Although that would be possible with discrete components the obvious solution is, as you realise, to use a micro, e.g. an Arduino.
     
  3. CFGraham

    Thread Starter New Member

    Feb 4, 2015
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    Hi Alec, thanks for the reply. I probably will go the Arduino route, but due to environmental reasons (using this in a darkroom) it would be a great to use discreet components if possible.

    Alternately, if I did use an arduino, is it possible to load a few typical motor sketches onto jump drive or some sort of portable uploader and just feed those to the microcontroller between batches so I don't have to carry the unit to a computer between batches?
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    An item you may find a little easier to program, is a Smart Relay, it looks like what you need to do is start one dir for a certain time, stop and pause, then start in the opposite dir for the same time, then repeat.
    You could buy some discrete timers, but then the cost would probably be more than you would pay for Smart Relay, especially off ebay.
    This would allow setting time in fwd/rev as well as total time on.
    You may have to initially set the motor rpm manually. And as I pointed out, it would be best to pause before going from fwd - rev.
    There are several makes of S.R. and many are just one make relabled .
    Max.
     
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    I'm not familiar with the Arduino, but someone else here may be able to advise.
     
  6. CFGraham

    Thread Starter New Member

    Feb 4, 2015
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    That Smart Relay looks very promising- thanks!
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
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    This is a series of tutorials on the Siemens, most are very similar in operation and some have free s/w or is available on the net.
    https://www.youtube.com/playlist?list=PLA76E3962AA81E960
    You can also program in simple boolean from the front screen, but a little cumbersome.
    I think I have a copy of the Siemens Logo s/w somewhere.
    Max.
     
  8. CFGraham

    Thread Starter New Member

    Feb 4, 2015
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    I found demo software for IDEC's version, which is free to try. It looks like you don't even need the smart relay module itself to run program simulations, which is great- I'll be able try it out before buying anything. Thanks again for the suggestion!
     
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