Heavy duty Solenoid

Discussion in 'General Electronics Chat' started by Transatlantic, Jun 29, 2015.

  1. Transatlantic

    Thread Starter Member

    Feb 6, 2014
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    I'm hoping someone can recommend a heavy duty solenoid that I can buy in the UK that has enough force to act as a persons foot pressing down on a bass drum pedal. I've been looking on ebay and have come across these :

    DC 12V 5Kg Force 10mm Stroke Push Pull Type Electric Solenoid Electromagnet

    Does that sound suitable? or will I need a bigger force? .. seems very cheap (too cheap?)

    As it's just an experiment, I don't really have any other requirements.
     
  2. strantor

    AAC Fanatic!

    Oct 3, 2010
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    That's worth a try but I suspect it won't work out optimally. For the drum kick I suspect you'll want variable "kick strength" otherwise you'll get the same strong BOOM or weak "...bump..." (I suspect weak "...bump...") every time. The solenoid isn't going to be variable. For variable I would suggest a DC motor with some sort of cam or pull string to actuate the pedal. You can control the motor with variable current for variable acceleration and torque (kick strength).
     
  3. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Since that is how most kick pedals work (with a cam and pull chain (bike chain)), adapting a motor to a kick pedal will probably be the most successful approach.

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  4. Transatlantic

    Thread Starter Member

    Feb 6, 2014
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    I mentioned the pedal as an example, I was actually going to attach the beater straight to the solenoid (no pedal at all), which is why I was looking for something powerful.

    But maybe the pedal/cam approach is better as it allows for a built up of momentum?

    As for the variable force, I thought I would just control that via the voltage applied.
     
  5. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    The cam approach is better because it allows a small force to operate a large load (beater). A solenoid may not be able to operate the beater. You'd have to measure the forces to be sure.

    Solenoids tend to be on or off devices. It is not easy to generate variable force with them. Varying the voltage most likely won't do it. PWM control might.

    Geared motors or servos would be a better driving force. They can be controlled finer.

    How were you going to control the solenoid?

    Just my 2cents. Just noticed strantor also said as much. Deserves repeating.
     
  6. strantor

    AAC Fanatic!

    Oct 3, 2010
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    You should apply a variable voltage to a solenoid and/or a relay to understand what happens. Really good exercise. Say you use a variable bench power supply applied to the solenoid/relay, and you slowly come up from 0V until the device starts to actuate, you will find that it instantly "snaps" to fully actuated position. There is no position control or torque control by variable voltage. The reason is because a relay/solenoid takes the most power at the beginning to get moving; once it's moved 1mm (for example) it takes less power for it to move 1mm further. And that much less power to move the next mm, and the next, and so on. It's an "avalanche" condition; an exponential decay in the power required to move from beginning to end of stroke. Once it starts, it goes, and that's that.

    EDIT: there is such a thing as a "linear" solenoid which can be variable in torque & position based on the voltage applied, but these are specially designed with tapered iron and are very expensive. Also they are typically pretty small. I wouldn't expect to see one beating a kick drum.
     
    djsfantasi likes this.
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