Suitable encoder for instrument knobs

[doveman]

I need to get a single shaft encoder to use to adjust the various heading bugs, altimeter settings, etc. Something that looks like this, with a serrated edge, would probably look the part although I'm happy to stick a serrated knob on a normal shaft if necessary.

 

I don't know much about encoders yet but I guess I want one with a large number of pulses per revolution, so that I can set the instruments quite precisely. I know I want one without any detents, which I believe are also known as infinitely variable. I guess I need one with a push-switch, so that I can use that to uncage where necessary (i.e. send the uncage command to DCS, I don't care if the physical control locks or not)

 

In my search, I came across this page from one manufacturer which has more details than my brain can handle! http://www.electro-nc.com/products/encoders.shtml Do I want mechanical, optical or magnetic? Absolute (which has 4 variations) or Incremental (which has 3)?

 

Even if that manufacturer has the right product, I can't order from them directly anyway, so if anyone has found a suitable encoder and can tell me where I can order it from, that'd be great.

 

I had a quick look on e-bay but what I found on there had very limited information. Farnell has this one, which looks the part but is detented and only 15PPR http://uk.farnell.com/alps/ec11e152u402/encoder-push-lock-11mm-30d-15ppr/dp/2065016?Ntt=EC11E152U402

[acemark]

Hi Doverman. You should decide how you are going to connect the encoder to the sim.(interface). The manufactor of the interface board will state what type encoder to use.

I am using a bodnar button box with use machanical gray code encoders.

You asked in a previous post about dual encoders. Did you mean rotory with push button. If so , the shark uses one on the abris right side.

Mark.

[doveman]

Hi Mark

 

I'll be using an Arduino Mega board but I don't think that dictates exactly what encoders I can use does it?

 

Re. dual encoders I mean dual shaft with push button on the inner shaft like this http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=75&products_id=196 The Shark Abris just appears to be a single shaft with push button.

[metalnwood]

If you are doing it with arduino then really any kind of encoder you want. Anything Leo sells will work otherwise places like digikey.

 

e.g. this is probably one Leo has http://www.digikey.co.nz/product-detail/en/288T232R161A2/CT3002-ND/203827

 

As far as the dual rotary encoders. Leo is the only person I know where you can buy them.

 

Make sure you are only looking at mechanical encoders, not optical.

[Warhog]

I bought 20 of these off ebay and they have worked great with the Button Box BBI-32 from Leo.

 

http://www.ebay.com/itm/10pcs-New-12mm-Rotary-Encoder-Switch-With-Keyswitch-US-/290598955713?pt=LH_DefaultDomain_0&hash=item43a90c2ac1

 

How can you go wrong with a price like that. They also have the push button built in which is really handy. Three tabs on one side of the encoder. Centre tab is ground and left and right go to inputs on the board. Stupidly simple I must say. There are two other tabs on the opposite side for the switch.

 

Buy a few and play with them.

[metalnwood]

Oh yes, ebay of course. Another pretty amazing place if you are playing around with electronics is aliexpress.com

 

looking around at arduino stuff there you will be amazed what you get for the prices. You just have to be sure if you are buying one or ten for the price.

[donbinator]

Thanks!!! I just ordered straight from your link. Man that is a GOOD price!

 

I bought 20 of these off ebay and they have worked great with the Button Box BBI-32 from Leo.

 

http://www.ebay.com/itm/10pcs-New-12mm-Rotary-Encoder-Switch-With-Keyswitch-US-/290598955713?pt=LH_DefaultDomain_0&hash=item43a90c2ac1

 

How can you go wrong with a price like that. They also have the push button built in which is really handy. Three tabs on one side of the encoder. Centre tab is ground and left and right go to inputs on the board. Stupidly simple I must say. There are two other tabs on the opposite side for the switch.

 

Buy a few and play with them.

[agrasyuk]

Now that we have encoders out of the way let's discuss what cheap and good looking knobs to use with them.

[doveman]

If you are doing it with arduino then really any kind of encoder you want. Anything Leo sells will work otherwise places like digikey.

 

e.g. this is probably one Leo has http://www.digikey.co.nz/product-detail/en/288T232R161A2/CT3002-ND/203827

 

As far as the dual rotary encoders. Leo is the only person I know where you can buy them.

 

Make sure you are only looking at mechanical encoders, not optical.

 

Why do you say only look at mechanical, if I can use any kind I want with arduino?

 

The digikey one you linked to (and that Leo Bodnar has) has detents, so wouldn't be suitable for the application I mentioned. It also has only 4 Pulses Per Revolution, which seems too low for accurate adjustment of the instruments, although I don't profess to be an expert on these things.

[doveman]

I bought 20 of these off ebay and they have worked great with the Button Box BBI-32 from Leo.

 

http://www.ebay.com/itm/10pcs-New-12mm-Rotary-Encoder-Switch-With-Keyswitch-US-/290598955713?pt=LH_DefaultDomain_0&hash=item43a90c2ac1

 

As far as I can tell, these are detented as well as it says 20 position, so they're not what I'm looking for. Says they have 20 pulses per revolution though, so I presume they'd at least have fairly decent precision and might be suitable for other applications.

[metalnwood]

Doveman, they are what you are looking for I believe. When you said no detents and infinite adjustabailty I assumed you were talking about not wanting a 12 position switch or similar.

 

The optical encoder will not have the detents but the others will, thats fine, thats what they all have. It's what lets you easily change the freq in the increments available. The switches don't have a hard stop, they can turn in any direction infinitely.

 

The optical encoder is complete overkill and would be harder to use and not in the package you would want.

 

Trust me, the mechanical encoder is what you are after ;) The ones you got are fine.

[doveman]

Nope, pretty sure they're not what I want ;)

 

I've not flown IRL but people who have tell me that Altimeter, VOR and Horizon knobs on analog gauges generally don't have detents, which makes sense as these things have to be tweaked very accurately and precisely, not in steps. I'm not talking about changing frequency on radios or that sort of thing, for which the detented encoders from Leo Bodnar are fine.

 

I don't think only optical encoders are without detents as I've seen product datasheets showing variations in the same (what appears to be mechanical, as far as I can tell) range with and without, for example http://www.farnell.com/datasheets/1676943.pdf

[bnepethomas]

Just a quick tip, buy a few of the encoders, and then test them with the encoder board you plan to use against the sim. I've got both the cheap encoders from ebay and the good quality ones from Leo Bodnar. There is subtle differences in timing between the encoders which means (ironically), the cheap ones work really well with OverPros' Arduino software but the more expensive ones don't read as well.

 

Both the cheap ebay and Leo's encoders work against Leo Bodnars BBI-32, but I am trying to reduce the number of boards in my new sims, and currently OverPro's Ardunino software works a treat so it's got the gong.

 

Cheers

Peter

[metalnwood]

An optical encoder will give you no detents if you want to have one like that. A detent on an optical one would probably only be there for tactile feedback.

 

 

VOR, altimeter etc all come down to the software, it's not the encoder that determines how much something moves but how you interact with the software.

 

For example, for the VOR, one 'click' (partial turn) of the mechanical encoder can be one degree, thats what happens with them most of the time in sims. It can take a while to go around 180 degrees when you do that so software will often change it, for example, in 5 degree increments when you turn the knob faster and one degree increments otherwise. This allows you to do fast changes in values as well as fine changes.

 

A mechanical encoder that every pit builder here and all over the place is using will do the job fine. Any other type and you will still have the same issues, if you need fine adjustments its hard to do large adjustments (and vice versa )unless you have the software help you, in the end it doesn't come down to the type of encoder.

 

I honestly think there is a misunderstanding of how you would operate them in a sim because I and everyone else I know has never found the problem you are describing?

 

Or at least the problem I think you are describing.

Edited June 13, 2014 by metalnwood

[Warhog]

And to continue from where Metalnwood left off , I use those same encoders specifically for setting pressure in the altimeter, setting up my HSI heading and course as well as the radio frequencies of the Comms and nav equipment on my A10. One more thing they are particularly good at is adjusting the gain for my NVG. Push of the button turns them on, left and right adjusts gain. Fast easy access and sensitive enough to make whatever adjustments you need. There is also software on Bodnars site that allows you to adjust the pwm so you can fine tune them for your specific need.

 

It sure won't hurt to try a few and see what you think for what they cost.

[doveman]

Just a quick tip, buy a few of the encoders, and then test them with the encoder board you plan to use against the sim. I've got both the cheap encoders from ebay and the good quality ones from Leo Bodnar. There is subtle differences in timing between the encoders which means (ironically), the cheap ones work really well with OverPros' Arduino software but the more expensive ones don't read as well.

 

Both the cheap ebay and Leo's encoders work against Leo Bodnars BBI-32, but I am trying to reduce the number of boards in my new sims, and currently OverPro's Ardunino software works a treat so it's got the gong.

 

Cheers

Peter

 

Which software by OverPro are you referring to Peter? I did a search but didn't find anything that looked to be about encoders, only joysticks.

 

I couldn't seem to find anywhere selling dual encoders other than Leo Bodnar and they're good quality, so I didn't mind paying almost £20 a piece, including knob, as I only needed a couple for now, although I'd soon change my mind if I needed ten of them! Because they're so expensive, I'm just going to use a single pair with a rotary switch to set which panel they control (GPS, COM1/NAV1, COM2/NAV2, ADF, DME) for my Dad's X-Plane.

 

If cheaper ones do work better with any particular software, I'd imagine that it's just a matter of tweaking the software to better match the encoder and that once correctly configured, you should find the more expensive ones work at least as well and hopefully last longer.

 

If it was just for myself, I probably would buy some of the cheap single encoders to try out, although I was a bit put off by some comments on one of the cheap sites (sparkfun I think) where they said 3 out of 5 of them didn't work and they had to take them apart and flip things around as they'd been constructed incorrectly, so I don't mind paying a bit more for something a bit better. However, I kinda need it in a hurry to try and get it ready for my Dad's birthday at the end of July and ordering from China it probably won't have even arrived by then! Hence why I'm looking for a UK supplier for this particular order.

[doveman]

An optical encoder will give you no detents if you want to have one like that. A detent on an optical one would probably only be there for tactile feedback.

 

Judging by the catalog I linked to showing detent and no detent versions in the same range, it looks like mechanical, not just optical, encoders come in no detent versions. Unless that entire range is optical or a mix of mechanical and optical.

 

VOR, altimeter etc all come down to the software, it's not the encoder that determines how much something moves but how you interact with the software.

 

For example, for the VOR, one 'click' (partial turn) of the mechanical encoder can be one degree, thats what happens with them most of the time in sims. It can take a while to go around 180 degrees when you do that so software will often change it, for example, in 5 degree increments when you turn the knob faster and one degree increments otherwise. This allows you to do fast changes in values as well as fine changes.

 

It's a bit of both really isn't it? If the encoder only sends a signal every 10 degrees, then the software can only adjust the instrument every time the encoder is turned 10 degrees or more. I still don't really understand the interaction between pulses and detents but looking at that Farnell catalog, it seems that range has exactly half the number of pulses to the number of detents, which makes no sense to me as it suggests that every other detent doesn't send a pulse and thus is redundant.

 

I would think that if for example an encoder sends 36 pulses per revolution, that means it sends a pulse every ten degrees, so the software can only do something every ten degrees. If the real-life knob only has a noticeable affect on the gauge when turned 10 degrees or more, then you should be able to set the software to mimic the real-life behaviour, so turning the encoder 10 degrees adjusts the gauge y degrees (whatever it does in real life) and turning it 360 degrees adjusts the gauge y*10 degrees, again the same amount as it would in real-life, so there wouldn't appear to be any need to make the software adjust the gauge different amounts depending on how fast the encoder is turned.

 

Now if the real-life knob has a noticeable effect on the gauge when turned only five degrees, then you'd need an encoder that sends 72 pulses per revolution to mimic that and I'm not sure such a thing even exists. The range here http://www.electro-nc.com/products/encoders.shtml shows they're mechanical encoders only go up to 24 PPR but the optical 900 series (discontinued) and magnetic 500 series range from 32 to 256. Looking at the datasheet for the latter, it seems to come in these options:

 

Quadrature 32, 64, 128 or 256 PPR

Tachometer 64, 128, 256, 512 PPR (w/ direction)

Absolute 10 bit PWM (1024 PPR) *

Quadrature 32, 64, 128 or 256 PPR w/ Z channel*

 

Assuming they're unaffordable or unsuitable for some other reason and to keep this example simple let's assume the highest PPR encoder you could get was 36 PPR, then using that every 10 degrees it's turned, you'd need to adjust the gauge the amount it would change if the real thing was turned 5 degrees. This obviously means that the encoder has to be turned fully twice, i.e. 720 degrees, to adjust the gauge the same amount as the real knob would when turned only 360 degrees but that's probably not severe enough to require using accelaration based on speed of turning (depending on how many rotations are needed in general of course).

 

Now if the real life gauge responds to only 1 degree movements of the knob and the encoder only sends a signal every 10 degrees, then I can see there'd be a problem as you'd have to turn the encoder fully ten times (i.e. 3600 degrees) to mimic the real life knob being turned fully once, so using accelaration based on speed of turning would be necessary.

 

Assuming I've understood how PPR works, I can't see how a 4 PPR encoder like the digikey one linked to could possibly be suitable. It's more than likely I don't understand how they work though ;)

[metalnwood]

The one I linked to from digikey, I didn't look closely at the specs but if it is the one Leo sells it is OK, you can get them with more pulses per turn and you may like that more.

 

At the end of the day, if you are trying to get something that will behave exactly the same as something in the aircraft then you will then first need to understand exactly how they work and then make a mechanical mechanism to gear up or down the turns required and use an encoder with or without tactile feedback to mimic it properly.

 

 

If on the other hand you just want to have it work and work well then you are overthinking it imho :) I still have an old go flight panel, lots of people are using them I will turn the knob nd tell you how many detents on it. thousands of guys using these panels to do exactly what you ant and they are happy as larry :)

[bnepethomas]

Which software by OverPro are you referring to Peter? I did a search but didn't find anything that looked to be about encoders, only joysticks.

 

I couldn't seem to find anywhere selling dual encoders other than Leo Bodnar and they're good quality, so I didn't mind paying almost £20 a piece, including knob, as I only needed a couple for now, although I'd soon change my mind if I needed ten of them! Because they're so expensive, I'm just going to use a single pair with a rotary switch to set which panel they control (GPS, COM1/NAV1, COM2/NAV2, ADF, DME) for my Dad's X-Plane.

 

If cheaper ones do work better with any particular software, I'd imagine that it's just a matter of tweaking the software to better match the encoder and that once correctly configured, you should find the more expensive ones work at least as well and hopefully last longer.

 

If it was just for myself, I probably would buy some of the cheap single encoders to try out, although I was a bit put off by some comments on one of the cheap sites (sparkfun I think) where they said 3 out of 5 of them didn't work and they had to take them apart and flip things around as they'd been constructed incorrectly, so I don't mind paying a bit more for something a bit better. However, I kinda need it in a hurry to try and get it ready for my Dad's birthday at the end of July and ordering from China it probably won't have even arrived by then! Hence why I'm looking for a UK supplier for this particular order.

 

 

Given you are in the UK and not needings lots of inputs, buying Leo's cards and encoders (and knobs) makes a

lot of sense, especially given shipping prices for Leo are good to the UK :)

 

Here's overpro's project http://forums.eagle.ru/showthread.php?t=117011&highlight=Overpro

 

Cheers

 

Peter