Help! Question about Multi-turn Pots

Question for all the experts out there, please be patient as a soldering iron in my hand could lead to a burning house/hospital trip. Noob.

Ok, so I’m building a button/encoder/pot box to control all the radios, etc on the right side of the F-86 cockpit. I’ve decided to use a multi (10) turn pot for the tuning knob for the ADF, I have used pots in the past with my Bodnar boards and they work great for controlling rheostats, etc in DCS.

Here’s the pot:

http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=103_81&products_id=194

You can click on the pic for a larger image of the pins and markings.

My question is: How do I wire this to the Bodnar board? There is no wiring diagram for this product, unlike for the other pots for sale on his site. The other ones use three wires, ground, input, and power (5V). Anything I’ve googled about this multi-turn pot seems to be two pins (1 and 3) bridged by one wire while pin 2 has it’s own wire, two wires total.

Again, how can I wire this so I don’t screw it up and kill the pot?

Thanks in advance :)

If you look at the picture it has a diagram of the pinouts on the body of the pot. Click on the picture to enlarge it.

The pin designation is from the shaft end #3 #1 #2 where #3 and #1 are the either end of the resistance and # 2 (furthermost away from the shaft) is the wiper. you'l see the little arrow pointing towards pin#3 and the letters CW.

Think #3 and #1 as the top and bottom connection of a normal pot and #2 as the wiper or center pin.

For Leo Bodnar boards the connection to an analogues input would be:-

+V to pin closest to the shaft end. #3.

GND (-V) to the next pin #1.

And ANA in to the bottom pin #2.

According to the marking that should get you increasing voltage input for clockwise rotation.

You can verify this with a DMM pins #3 and #1 will always be about 10Kr +/- a couple of %

Specs for the pot link here.

Soldering shouldn't be difficult it's a learned skill so some practise first. :D

<edit>

My question is can you actually use an analogue input to control the radio frequency, usually it would be a switch?

Thanks for the replies!

Yeah, the F-86’s Radio Compass (ADF) was pretty archaic by today’s standards, you used a crank handle to change frequencies by tuning it like an old AM/FM radio (Nicknamed a “coffee grinder” ADF). This is why I think a multi-turn pot is the best choice, the usual pots (see below) have only a 270 degree travel which would be too coarse.

The UHF radio, however, uses a channel selector for preset frequency selections so a rotary encoder works fine.

I’ve used these pots from Bodnar’s site before and they work great:

http://www.leobodnar.com/shop/index.php?main_page=product_info&cPath=103_81&products_id=193

As you can see, there is a simple wiring diagram where the 3 pins are connected so the middle one is the input and the outers are ground and +5V.

So, using the above diagram as guidance, you are saying that the multi-turn pot is basically the same where:

Pin 1 = black wire - connect to ground

Pin 2 = green wire - connect to input

Pin 3 = red wire - connect to +5V

I’m not too concerned about which way to turn to inc/decr voltage as I could just invert the axis in settings if the behaviour doesn’t match the direction of rotation in the cockpit... right? :music_whistling:

Thanks again!

 

I’ve used these pots from Bodnar’s site before and they work great:

 

As you can see, there is a simple wiring diagram where the 3 pins are connected so the middle one is the input and the outers are ground and +5V.

 

So, using the above diagram as guidance, you are saying that the multi-turn pot is basically the same where:

 

Pin 1 = black wire - connect to ground

 

Pin 2 = green wire - connect to input

 

Pin 3 = red wire - connect to +5V

 

I’m not too concerned about which way to turn to inc/decr voltage as I could just invert the axis in settings if the behaviour doesn’t match the direction of rotation in the cockpit... right? :music_whistling:

 

Thanks again!

Yes you can simply invert axis, works fine and Yes the pin numbers are correct but the pin numbering on the 10 turn pot is different. :)

Just to be sure the terminal numbers from the shaft end is 3,1,2 different to a "normal" pot.

Red +5V, Black ground, Yellow (Green in your case) analogue in on your Leo Bodnar board. Check that PDF I linked previous and a handy picture here.

Or if you prefer.

Images modified for illustration from,.

http://www.leobodnar.com/shop/

And

https://www.bourns.com/pdfs/3590.pdf

Thanks so much for the help, everything works perfectly in the Windows control panel! Now, just imagine my ecstacy (sarcasm) when I went to assign my new 10-turn pot to the ADF tuning crank in DCS and discovered THERE IS NO AXIS FOR THAT.

:wallbash:

So now I get to decide do I throw a rotary encoder in there or do I use a Momentary switch, left/right, spring loaded to center. Personal preference, I guess.

Time for me to petition DCS to get that axis added for pit builders.

Thanks again for your help! :D

Button box in question is at lower right, waiting to be mounted in cockpit. Monitor shows radio panels I have simulated with the new box.

You can use this multi-turn pot for elevator trim, although 10 turn will result in a very slow adjust - ideal is ~3 turns.

However looking at the Leo Bodner site rotary encoders are fairly straight forward, you connect the common GND and the *2 signal wires to 2 inputs and use the config software.

Leo Bodner encoders.

Pretty much any bi-phase rotary encoder should work.

Use the config software to tell the USB interface that the 2 inputs you connected are in fact a rotary encoder then assign them in DCS as the up or down button repeat for units tens hundreds as required.

I think that's what Mr Burns was aluding to :)

*Some encoders have an additional momentary push switch that can also be used and assigned in DCS

Nice pit BTW. :thumbup:

Yeah, I’ve already installed a few encoders for other inputs and they work pretty well, but they aren’t good for something like this when there’s a large range of travel from one end to the other.

Is there a way to get a larger change with each encoder pulse without getting into lines and lines of code? There’s a balance between speed and precision as well, too much of a change with each pulse and you can jump over the frequency/value are looking for.

The pit is an Obutto Revolution, no major mods, just using the table top arms as button box mounts. Still a couple of boxes to add, but I’m running out of room :) I have a landing gear control box to add but I’m not sure how to attach it yet, leaning towards RAM mount hardware right now.

The other thing is finally getting off my lazy butt and printing off the adhesive labels for all the switches. I have the correct font ;)

You may have to experiment perhaps with a higher resolution rotary encoder something like this.

Not this specific unit.

Now this unit has 200ppr not 16ppr so it's like more like 14 times the pulse rate! Now if it works with the Leo Bodnar USB and it should but the higher ppr could be filtered in the 836 software or there may even a pulse rate limit within DCS, I just haven't used one with the 836.

<edit>

The 836 appears to set the Pin to a pull up state so you would need to have an A6AZ-CWZ3C type which would be open collector 90deg bi-phase the unit listed wouldn't work unless you could change the state to Pin, perhaps this could be achieved with the setup software, but I don't know ATM.

The Pin mode can be changed at the programming level.

Alright here is a possible solution for your ADF tuning.

It's the Broadcom model HRPG-ASCA#54R

200 PPR but the kicker is it's about $35USD each although can get the price down to just over $10USD each but minimum purchase is 150 units. :cry:

Maybe have a look here Still might be able to use your 10 turn pot.

Thanks for the heads up! I’ve given things a preliminary read through, once I get home tomorrow I’ll start experimenting. :)

Ok, making progress, but still not completely there. Was able to add an axis line to the joystick default.lua file. I can assign the multi-turn pot to an axis in the control options page now and it works as far as I can tell (white line moves horizontally as I wind the pot back and forth), but it still won't actually work in the game. Turn the physical crank and the one in the game cockpit won't move...

Any ideas?

Line I added is here:

{action = radio_compass_commands.ARN6_TUNING_CRANK_AXIS,     cockpit_device_id = devices.AN_ARN_6_RADIO_COMPASS,     name = _('AN/ARN-6 Audio Tuning Crank'),     category = {_('AN/ARN-6 Radio Compass'), _('Right Side Panel')}},

Again, thanks so much for all your help!

This is out of my comfort zone here,.. :D

But looking at the the example from LeCuvier he doesn't have that brace in the statement.

category = {_( ... as in category = _( ... which of course you might have to remove one of the braces at the end of the statement.

I could be wrong but I'm trying to take in the video from Deezle as well.

As an aside I ordered a couple of HRPG-ASC#54 s to have a play with, that stuff I understand slightly better. :thumbup:

Maybe LeCuvier or Deezle could chime in on the lua code.

I think the double brace bracket is due to the two control category names listed one after the other?

Can you buy multi turn rotary switches in 4 or 8 position versions? EG Bleed Air and Ins inputs in the F/A-18C.

Can you buy multi turn rotary switches in 4 or 8 position versions? EG Bleed Air and Ins inputs in the F/A-18C.

not sure exactly your requirements.

2 pole 4 Position

And maybe?

2 to 12 position 1 pole user settable.

I think they all stop after either 4 turns or whatever you set it at so you have to go back around, i wanted to go straight from pos 4 to pos 1.

This day and age that sounds like industrial switch gear or at least cheap industrial.

Might cust have to check with supplier but it looks like it might continuously rotate with 90deg set points?

I think the double brace bracket is due to the two control category names listed one after the other?

Correct. The curly braces enclose a comma-separated list of categories. It's pointless though to have two categories for an axis, because when you are in the axis page you can no longer filter by category.

I think they all stop after either 4 turns or whatever you set it at so you have to go back around, i wanted to go straight from pos 4 to pos 1.

You want the switch to "wrap-around" from position n to position 1?

I found switches from Mouser Electronics https://eu.mouser.com/Electromechanical/Switches/Rotary-Switches/_/N-5g2i?P=1ytcygkZ1ytibi9

These switches have e.g. 2...4 or 2...8 positions. The number of positions is set with a "stopper plate". I wonder if, when you take the stopper plate out altogether, you might be able to wrap around?

This day and age that sounds like industrial switch gear or at least cheap industrial.

 

Might cust have to check with supplier but it looks like it might continuously rotate with 90deg set points?

I was looking at those but it just seems overkill, I wonder if could mod one to turn continuously.

@ Mr_Burns. I'll let you know when mine arrives. :)

My rotary encoders turned up and I have the decoder prototype up and running and about ready to interface it to the Leo Bodnar USB. And yes I'm decoding separately which gives me a few options over having the USB interface decode it.

The encoder HRPG-ASCA#54R 120CPS, they are a tad expensive but worth it I think.

Prototype Decoder.

:thumbup:

Here you go Mr_Burns.

Here's the switch body overall about 82mm or 3 1/4"

The front mounting plate is about 48mm or 1 7/8"

The switch does rotate paste 360 deg with 90 deg stops, however in it's supplied configuration it is 1 in 3 positions connect with an off in the 4th position with 2 poles.

It does have a "mild" industrial feel about it in that you know you've turned the switch to the next position, just saying. :thumbup:

HTH

Thanks frag - looks like just the job!

Perhaps when I thought it was a bit overkill the industrial feel actually is pretty cool in a pit, like you said, you know its been switched!!

Off to purchase...