DIY Air-Core Movements for Analog Gauges

[Mike Powell]

Periodically I sit alone in a corner and play with magnets. The most recent such occurance has resulted in DIY air-core movement.

 

Why? Well, because I can, and because the air-core is small enough to make a 1" diameter gauge and strong enough to spin a pointer in a 3 inch gauge. Besides, magnets are just neat!

 

The rotor in this movement is a 5mm diameter neodymium tubular magnet mounted on a bit of 0.035 stainless steel wire. The bearing which supports the rotor shaft is a half inch of 1/16" diameter brass tubing which I enlarged very slightly with a 0.85mm drill bit. This tubing is held concentric with respect to the movement body, a piece of 1/4" diameter brass tubing.

 

 

Once this was sealed, I glued four wire guides to support the two field windings. The cylinder to the left is chunk of 3/4" thin wall electrical conduit which serves as a magnetic shield, and protection for the thin field wires.

 

 

Each winding consists of 600 turns of #38 enameled wire.

 

 

The movement works well when driven by 5 volts on the windings. I built a PIC16F648A controller to drive it using pulse width modulation. The controller accepts commands across an RS-485 shared instrument bus. The board on the left is the RS-232 to RS-485 adapter which hangs off the computer's serial com port.

 

Works great.

 

[hog_driver111th]

Mike, any chance you plan on making gauges like Alt, VVI, Airspeed so the rest of us can buy them? I think the only way I'd understand most of this stuff is if you came over and physically made one with me. (beer would be on me).

[Mike Powell]

Mike, any chance you plan on making gauges like Alt, VVI, Airspeed so the rest of us can buy them? I think the only way I'd understand most of this stuff is if you came over and physically made one with me. (beer would be on me).

 

In my current situation, (retired, incredibly lazy, and living in a small house made even more cramped by adult children moving back in), I can't see myself making stuff for sale. However, if there is continuing interest, I will probably continue to publish books about flight sim. Almost certainly, these sorts of projects would be included. Design files for PC boards and hex files for microcontrollers would be posted on a support page.

 

[i suppose books qualify as "stuff", but I don't actually make them. I just write them. I get a printing company to make them and ship them to me so my garage becomes even more cluttered.]

[PanelBuilder]

Very cool stuff, Mike.

 

Colin

[Peter_Pilot]

Mike,

 

It is always great to see your latest projects, thanks. I wish I had the skill and energy to make one of your PIC based systems, maybe one day. I have certainly used your advice making my Hall sensor based joystick and collective lever for DCS Blackshark, they work really well. I took my setup along to my local flight sim club yesterday, it was well received which helps my satisfaction considering how long it took to make. Unfortunately one of my Hall sensor assemblies got trodden on but luckily it will not take too long to fix.

 

Are all your projects individual efforts or do they end up in a cockpit of yours?

 

Best wishes,

 

Pete.

[Mike Powell]

Colin, thanks for the kind words.

 

Pete, currently I have an abandoned 206B project and no room, but I have hopes.

[KLaFaille]

Thanks for posting this here Mike. This is another project that I've got mulling around in the back of my mind that I'm going to have to undertake at some point. There is always so much to do with this "hobby". ;)

 

Red