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Topic: [SOLVED] Heat dissipating of a solenoid (Read 412 times) previous topic - next topic

Johan_Ha

Jan 28, 2018, 11:07 pm Last Edit: Jan 30, 2018, 05:30 pm by Johan_Ha
EDIT: Well, it's not solved, but I abandoned the approach.

I have this solenoid (video).

That's a video of my old Canon typewriter, which I'm turning into a plotter. The thing is, I'm going to reuse almost everything. The stepper motors for horizontal and vertical movement. And this solenoid for pen up pen down activity. The trick is that when the solenoid is activated, the stepper motor rolls the paper cylinder. When the solenoid is passive, a clutch switches the transmission and the same stepper motor performs a movement, which has to do with the correction tape of the typewriter. Since I won't be using any correction tape, I'm going to use that movement for the pen up pen down.

My question is, will 5 W be too much for this solenoid. I need the solenoid to be activated most of the time, because it transfers the movement to the paper roll. Only on pen down or pen up movement the solenoid is passive. The solenoid will use 18 V, and it takes some 240 mA with that voltage. That would be some 4.5 W. In the video you see how the solenoid is mounted. Is there a chance that the metal plate will dissipate enough heat?

If it is too much, I need to glue the clutch and figure out another way to operate the pen up pen down.
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If you ask for help and write 'u' instead of 'you' because you think it's convenient, I will write 'no' instead of 'yes'. For same reasons.

Paul_KD7HB

Your problem is not the metal plate dissipating the heat. It is the copper wire and the insulation in the solenoid. They will get super hot before any heat ever gets to the mounting plate.

You need to put a current limiting resistor in series with the solenoid power to limit the current to just that amount necessary to do what you want. If the solenoid still gets hot, then it can't be used that way.

Paul

Johan_Ha

Ok. I have to glue the clutch. I was thinking of reversing the solenoid so that it would be passive most of the time. But depending on the image that the plotter will draw, there might be very much activity with the pen up pen down movements and the whole machinery might be a bit clumsy for that.
____________________

If you ask for help and write 'u' instead of 'you' because you think it's convenient, I will write 'no' instead of 'yes'. For same reasons.

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