Roll your own magnetic actuators


#1

I was considering rolling my own magnetic actuator for a light indoor RC aircraft. On youtube someone made a spool that came apart. He rolled the “magnet wire” onto the spool. Then added PVA glue. As he disassembled the spool he added more glue. He ended up with a stiff coil of just wire and glue. Very light.

Two questions.

What sort of resistance should I aim for? I want to use “1s” so 3.4-4.2v If I drive it with a PWM, probably at 100Hz ish, will the inductance dominate or can I just use ohms law? On a news group they were talking 25 - 50 Ohms but it was not clear if they were using pwm and at what frequency.

I will place a magnet in the coil and this will turn and move the control surface. Do you think I should drive it using alternating field so 50% is centred or use an on off approach where 0% is the middle and polarity is reversed to go from moving up to moving down? The control surface will be floppy but I think it will tend to centre, rather than droop, during flight from the air as it moves.

I may try and print a spool that disassembles with a shaft to fit in a drill/driver/Dremel. I may even try and print a very light spool and leave the wire on it. It will be slightly heavier but could be easier to mount and repair, etc.


#2

I printed a spool. It needed some “finishing” to get it to fit together. I used cling film and wound on 25M of “magnetic” wire. The coil was too large for a small plane. I have made a second one with 5M and this is much better. I need more than one so I will try and make one that is 10M to try and increase the resistance and make it stronger force. I now need to make the electronics to drive it. http://www.thingiverse.com/thing:1890161