How to make a magnetic actuator - RC Groups
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Jan 16, 2011, 04:02 PM
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How to make a magnetic actuator

Hi All,

I am trying to find plans or instructions to make a micro magnetic actuator. Can some one help me please? I know that these can be bought, but I want to make one myself.
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Jan 16, 2011, 04:19 PM
Registered User
An actuator is just a coil with a magnet centred in the coil.

Making them has been discussed often in the Indoor and Micro forum though less so recently. E.g.

Jan 18, 2011, 12:04 AM
Registered User
Originally Posted by slipstick
An actuator is just a coil with a magnet centred in the coil.

Making them has been discussed often in the Indoor and Micro forum though less so recently. E.g.

Thank you for the information. I really appreciate it.
Jan 19, 2011, 05:36 AM
Registered User
MGeo's Avatar
This old thread also has much how-to info in it:
Jan 22, 2011, 04:20 PM
Registered User
check this video out this is how i learnd... SUPER EASY!!

Actuator Servo Home-built video (very Cheap) (6 min 31 sec)
Feb 16, 2011, 07:01 AM
I love HAM
Hi all,

I am trying to make a 25 Ohm coil and found some wire inside an old brushed motor. There were three windings in it; took one off and ended up with a 1.75m (5.8') piece of wire that looks to be about 0.2mm thick (including insulation)

The resistance of this length stretched out is ~3 Ohm. I then wound it up in a coil and measured resistance again, and it is still 3 Ohm. I never was very good in physics class (too busy chasing the girls) but I thought the resistance would be higher when the wire is wound up in a coil?

Will I be needing 14.5m (48') of wire to achieve my desired resistance of 25 Ohm? I was hoping to make something very small to put on one of those X-Twin planes but with such a big coil I wonder if it's going to be able to take off at all

Please help out this electronically challenged old fart; I promise I'll pay attention this time
Feb 16, 2011, 07:23 AM
Registered User
The resistance will not change due to winding a coil. What changes is the inductance! This is very important for a coil. It causes the current to ramp
up, and be limited as long as the core is not saturated. With no core,
you have an air core inductor. Not sure about the dynamics of a magnet core, but there is more than resistance at play here. The L of your coil will cause it to draw less current than the straight wire. The magnetic force on the magnet is proportional to the current.
Feb 16, 2011, 08:23 AM
I love HAM
Thanks jglenn!

Does that mean that - using this wire I mentioned - I would really need about 48' to reach the desired resistance? It seems like an awful lot to me. Do I need to use thinner wire for the application that I have in mind?
Feb 16, 2011, 08:25 AM
Registered User
Resistance is basically defined by the length (and size) of wire. Winding into a coil has no effect at all on the resistance.

So yes, you either need much thinner wire or a much greater length.

Feb 16, 2011, 08:29 AM
I love HAM
Thanks Steve!
Feb 16, 2011, 06:45 PM
Registered User

I don't know where you got your specs from. There are a lot of tradeoffs between wire gauge, R, current, field intensity, etc. That much wire will
take a huge bobbin, unless as fine as hair. That fine is hard to strip,
taking the enamel off the ends. They have polythermaleze wire that you
just solder, and it goes thru. Here are some links to help:

THis last one has a calculator spreadsheet thing.

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