Help with hall effect sensors

[nosecone]

Hi all
Playing around with hall effect sensors as an option instead of using pots.
My cyclic setup has two horizontal rods that control the
forward-back and left and right movement.
8054

Movement of travel on both rods is about 70mm
I need to setup some kind of rotating movement for the sensor to work
What size magnets would I need to get, in order to give me the best results

Cheers

Rhys

[iwik]

Hi Rhys,
Have you considered these,

Honeywell - HRS100SSAB180 - Sensors, Switches & Relays - Sensors - Allied Electronics (http://orig-10001.allied.att-dsa.net/search/productdetail.aspx?SKU=70152972)

Expensive but very reliable. Available in 90 and 180 degrees.

Les

[nosecone]

Hi Rhys,
Have you considered these,

Honeywell - HRS100SSAB180 - Sensors, Switches & Relays - Sensors - Allied Electronics (http://orig-10001.allied.att-dsa.net/search/productdetail.aspx?SKU=70152972)

Expensive but very reliable. Available in 90 and 180 degrees.

Les

Hi iwik
what is the main difference between rotary potentiometers and these hall effect sensors. I assume
you still need to hook up a lever arm to the shaft like a potentiometer ?

Cheers

Rhys

[fsaviator]

Rhys,

the difference is that there are no moving parts to wear or degrade in these hall effect sensors. They are a shaft surrounded by magnets but there are no touching parts to wear out, and no place for dust to gather.

I've bought these two sensors for my yoke, but haven't gotten around to mounting them. They are smooth on a multimeter though.

Warren

[iwik]

Ryhs,

Warren described it perfectly. They are like a potentiometer to hook up. Inside is a hall effect sensor, bit like a transistor.
Its current varies depending on the magnet field it passes close to. Hence the voltage out changes just like a Potentiometer.
But there is no wiper rubbing against a track so nothing to get dirty or wear. If you look at the link you will see what I mean.
Here is a DIY solution,

http://www.mycockpit.org/forums/i-o-interfacing-hardware/22267-dead-simple-hall-effect-pot-replacement.html

Hope it helps.
Les

[petersm99]

Hello Rhys, The Honeywell sensors may be hard to get.The only place where I have found them available in normal order quantities and for a reasonable price was at Allied Electronics. It may however take some time as these are controlled items and you may need to be cleared for export/import/use. I hope this helps. Best Regards, Marc

[kermit]

Also look at Xsim.de they have some topics about the stuff
greetz

[Westozy]

Hi Rhys,
It is quite common to see lever arms fitted to potentiometers/HE sensors when trying to pick up linear movement from a mechanical component and this is something I always try to avoid. (To be honest, I avoid HE sensors also, a decent potentiometer will always do the job and last many years). There are obviously issues with the end of a lever arm moving through an arc and in addition the signal from the pot or sensor will not be linear. There is a very simple solution using items easily sourced. An example - recently I fitted a potentiometer to the tiller mechanism on real B747 nose section that I have been working on for quite a while. The tiller handles are cross connected by a wire rope cable that is about 3mm in diameter. Full cycling of the tiller left to right produced a linear movement of the cable of 284mm. I wanted to make this cable rotate a pulley fitted to potentiometer at least 270 degrees so a simple calculation is required - The circumference of this pulley has to be [(284 x 4) / 3] answer = 378.7 Divide this by Pi to determine the pulley diameter - 378.7 / 3.142 = 120.52mm. So a pulley diameter of 120mm will do the job.
The second part of the mechanical solution is how to make the Boeing cable drive the pulley and this is quite easy. I mounted the pot with the pulley so the groove on the pulley is practically touching the Boeing cable but it does not rely on friction to drive it. I used some 40LB stainless steel trace wire bought from a fishing shop and this is attached to the Boeing cable with a cable grip about 200mm away from the pot position then wrapped around the pulley two times and stretched along the Boeing cable and clamped again on the other side. The result is a positive drive on the pot of 270 degrees and it provides a true linear signal, the tillers work perfectly. I made the pulley out of 6mm thick material and machined a groove on the outside of it for the trace wire, the pulley has a small boss to lock it to the pot. The total parts cost is about $20 and this will provide years of accurate function!

Cheers Gwyn