Rotary position sensor ideas? - UK Vintage Radio Repair and Restoration Discussion Forum

Steve G4WCS · 12th Dec 2019, 9:52 am

Im thinking about putting together a small 12 volt rotator system, for my truck static mobile hill topping next year.

doing a search of worm gears has brought up a cheap source of 12V dc worm geared motor drives, which has much simplified the drive design, however I need a simple means of position indicating.

I have in my collection a load of small reed relays, so could do a fixed board with a number of those on and a rotating disc with a small magnet on it, and a number of leds on the control box, but this would mean multicore wiring between the rotator and control box.

I also have Bourns precision 10k 10 turn pots, so could feed the control unit with a DC position dependent voltage. this could then be used to drive a number of options for position indication, ranging from an LM3914 driving bar graph LEDS, to an a/d converter, display driver, and a 7 segment LED degree display, but it really doesnt need to be so complicated.

Has anyone either done this or seen a tried and tested circuit, don't want to re-invent the wheel if possible.

Radio Wrangler · 12th Dec 2019, 11:51 am

How about one of those little fluxgate magnetometer compass modules mounted on your mast.

Whichever way you park the truck, the readout gives you the bearing.

David

Steve G4WCS · 12th Dec 2019, 2:42 pm

Quote:

Originally Posted by Radio Wrangler

How about one of those little fluxgate magnetometer compass modules mounted on your mast.

Whichever way you park the truck, the readout gives you the bearing.

David

are they bluetooth or something ?

posting this here so I dont lose the link

https://www.electro-tech-online.com/...ircuit.120242/

G6Tanuki · 12th Dec 2019, 2:58 pm

The commercial rotators by the likes of CDE, Hy-Gain etc generally just use a potentiometer, a DC supply and a meter.

Of course a traditional pot only has something like 300 degrees of rotation, so you would either need to gear it down, or use a 5- or 10-turn over a restricted part of its travel.

A 270-degree meter (as used on industrial control-panels etc) suitably recalibrated would make a good angle-of-twist display.

M0FYA Andy · 12th Dec 2019, 3:08 pm

Use a synchro transmitter and receiver.

Andy

12th Dec 2019, 4:24 pm

Quote:

How about one of those little fluxgate magnetometer compass modules mounted on your mast.

Brilliant!

Funnily enough I have just used said motor for my loop antenna. I used a 2:1 reduction gear to a pot and an old radio control servo board to "do the magic", works a treat over 100 feet of cable. I merrily send a pulse between 1 and 2ms and it goes to a position.

Here it is before installation.

Terry_VK5TM · 13th Dec 2019, 12:36 am

Quote:

Originally Posted by Steve G4WCS

are they bluetooth or something ?

No, you need extra electronics of some sort to read the data out of them.

12th Dec 2019, 9:52 am	#1
Steve G4WCS Heptode Join Date: Sep 2004 Location: Preston, Lancashire, UK. Posts: 632	Rotary position sensor ideas? Im thinking about putting together a small 12 volt rotator system, for my truck static mobile hill topping next year. doing a search of worm gears has brought up a cheap source of 12V dc worm geared motor drives, which has much simplified the drive design, however I need a simple means of position indicating. I have in my collection a load of small reed relays, so could do a fixed board with a number of those on and a rotating disc with a small magnet on it, and a number of leds on the control box, but this would mean multicore wiring between the rotator and control box. I also have Bourns precision 10k 10 turn pots, so could feed the control unit with a DC position dependent voltage. this could then be used to drive a number of options for position indication, ranging from an LM3914 driving bar graph LEDS, to an a/d converter, display driver, and a 7 segment LED degree display, but it really doesnt need to be so complicated. Has anyone either done this or seen a tried and tested circuit, don't want to re-invent the wheel if possible. Attached Thumbnails

12th Dec 2019, 11:51 am	#2
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,876	Re: rotary position sensor ideas How about one of those little fluxgate magnetometer compass modules mounted on your mast. Whichever way you park the truck, the readout gives you the bearing. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

12th Dec 2019, 2:58 pm	#4
G6Tanuki Dekatron Join Date: Apr 2012 Location: Wiltshire, UK. Posts: 13,998	Re: Rotary position sensor ideas? The commercial rotators by the likes of CDE, Hy-Gain etc generally just use a potentiometer, a DC supply and a meter. Of course a traditional pot only has something like 300 degrees of rotation, so you would either need to gear it down, or use a 5- or 10-turn over a restricted part of its travel. A 270-degree meter (as used on industrial control-panels etc) suitably recalibrated would make a good angle-of-twist display.

12th Dec 2019, 3:08 pm	#5
M0FYA Andy Nonode Join Date: May 2007 Location: Preston, Lancashire, UK. Posts: 2,511	Re: Rotary position sensor ideas? Use a synchro transmitter and receiver. Andy