How to connect wires to this mini switch

[Kaellis991]

I wasn't sure where to find out how to do this so I thought I'd ask some cockpit builders. I am hoping someone has the experience to give me some direction.
What are the options to connect a 22 AWG wire to these really small switch pins?

[ame]

Sorry. Can't see your image without an account. Can you attach it directly?

[Kaellis991]

So I checked out the dropbox help...and since I haven't used this account in a while I find out something I didn't know...

As of September 1, 2017 public links have been disabled for all users. See below for more information.
As of March 15, 2017 the Public folder in your Dropbox account has been converted into a standard folder. By default this folder is private to your account. This transition will occur automatically.

You would think they'd delete that instruction text file on their web pages.."How to use the Public folder.txt."

I think I found the attachment command.

[blueskydriver]

Where did you get the switch?

[ame]

Ok. I see the image. It is a DPDT pushbutton switch, which can be latching or momentary. You should buzz the pins with a multimeter, but you'll probably find that you have two independent groups of three pins. The centre will be common (in each group) and the edges will be normally open (NO) and normally closed (NC).

The switch is designed to be mounted on a through-hole PCB. You might find the pin pitch will fit perfboard or stripboard, which would make an ideal transition board from the switch pins to the wire. However, you could solder your wire directly to the pins if you like.

[Kaellis991]

Where did you get the switch?

Switch was purchased through amazon based on the parts list from the builder of the transponder.
https://cessna172sim.allanglen.com/docs/avionics/bendix-king-kt76c/

[Kaellis991]

Ok. I see the image. It is a DPDT pushbutton switch, which can be latching or momentary. You should buzz the pins with a multimeter, but you'll probably find that you have two independent groups of three pins. The centre will be common (in each group) and the edges will be normally open (NO) and normally closed (NC).

The switch is designed to be mounted on a through-hole PCB. You might find the pin pitch will fit perfboard or stripboard, which would make an ideal transition board from the switch pins to the wire. However, you could solder your wire directly to the pins if you like.

I know how the switches function, that's the easy part. Soldering them is the challenge.
I tried the soldering by just laying the wire along the length of the pin. The diameter of the 22awg wire is approx. the same as the width of the pin and they are so close together I am finding it very difficult to not bridge over to the next pin with the solder. The other problem is the area of contact between a round wire and a flat pin. It seems to me that the "wire" needs to be flat similar to the connectors on an IC that is soldered to a PCB. Perhaps stranded wire is the better way since the solid wire is not flat? I might be able to slip the pin into the middle of the stands and solder all around.

I will keep trying the soldering approach because I do not think the perfboard will work considering how the switches need to be installed in the faceplate...see images of where the switch is installed at this link.
https://cessna172sim.allanglen.com/docs/avionics/bendix-king-kt76c

[Joe Lavery]

The way to solder to these pins is firstly to have a very fine soldering iron tip.
Then using the iron, coat the pin with a small blob of solder, let it run along the pin. Next twist the wire (assuming it's multi stranded) and hold the iron on the wire adding the solder (once it's hot enough) until it coats the wire. The trick is to have enough solder but not enough to bridge the pins.
I use one of those multi arm holders to hold the switch, then offer the wire to the pin and just touch it until you see the solder melt. Remove the iron straight away, but hold the wire for a couple more seconds until the solder has hardened.

After you've done the first couple you will develop your own method. When I first started I had similar problems, but now I can solder SMD (Suface Mount) devices with ease; even SMD chips.

Best of luck (it's all a learning curve)

One more thing I use heat shrink tubing on each pin, it makes sure they don't contact and strengthens the join.

Joe.

[Kaellis991]

The way to solder to these pins is firstly to have a very fine soldering iron tip.
Then using the iron, coat the pin with a small blob of solder, let it run along the pin. Next twist the wire (assuming it's multi stranded) and hold the iron on the wire adding the solder (once it's hot enough) until it coats the wire. The trick is to have enough solder but not enough to bridge the pins.
I use one of those multi arm holders to hold the switch, then offer the wire to the pin and just touch it until you see the solder melt. Remove the iron straight away, but hold the wire for a couple more seconds units the solder has hardened.

After you've done the first couple you will develop your own method. When I first started I had similar problems, but now I can solder SMD (Suface Mount) devices with ease; even SMD chips.

Best of luck (it's all a learning curve)

One more thing I use heat shrink tubing on each pin, it makes sure they don't contact and strengthens the join.

Joe.

So I tried again and am having some success. With time it will get better. Will have to figure out a away to stabilize my hand though Thanks.
What's unfortunate is the alligator clips on my "helping hand" is crushing the switches.

[Joe Lavery]

I also use a small bench mounted vice, it has rubber jaws so doesn't damage whatever I'm working on.
Yes I know what you mean about shaking, I have a small strip of foam on the edge of my bench that I rest my wrists on... It helps to keep my hands steady. But you will soon develop a method that works for you.
It's surprising how adaptable you can be when you stick at it. 

Regards
Joe.

[BushPilotSimmer]

Use 1.5mm solder wick and flux for large solder bridges. Reheat the small bridges to suck the solder onto indiviual traces.

Hugh

[blueskydriver]

Get one of these:

https://www.amazon.com/Aven-17100-150-Lead-Free-Solder/dp/B017LG2FUS

Use it to dip the wire tips (called tinning them) into the heated solder, let it cool. Then, with solder iron, you touch the tinned wire to the pin(s) just long enough for it to stick, move iron away, let it cool and that's it.

You can also tin pins for insertion into a PCB board, then you reheat with solder iron and it will adhere to the board.

Also, mind the wattage of the solder iron, too high is not good; a 20w-40w switchable is best for wires, lower wattage for delicate circuitry.

By the way, I do have one of these solder heating units myself....

John

[Kaellis991]

Get one of these:

https://www.amazon.com/Aven-17100-150-Lead-Free-Solder/dp/B017LG2FUS

Use it to dip the wire tips (called tinning them) into the heated solder, let it cool. Then, with solder iron, you touch the tinned wire to the pin(s) just long enough for it to stick, move iron away, let it cool and that's it.

You can also tin pins for insertion into a PCB board, then you reheat with solder iron and it will adhere to the board.

Also, mind the wattage of the solder iron, too high is not good; a 20w-40w switchable is best for wires, lower wattage for delicate circuitry.

By the way, I do have one of these solder heating units myself....

John

Easier said than done. ^ Takes a real steady hand. That pin is only .025 inches wide. Less than 1/32" and same width as 22 AWG. Lining them up perfectly has been a real challenge.
I have a Hakko and have been trying out different tips and heat combinations. Using liquid flux, paste flux, tinning pins and the wire, all the usual tips and tricks. These tests have all been with solid core wire. Stranded wire might work better so I will try that tomorrow. Still a work in progress but making some headway. One time it works and the next time it goes to crap. Consistency is the secret to everything isn't it? Thanks to all for the input.

[ame]

Ah, well I'm glad you know how switches work. It means you won't solder the wires to the wrong pins. And that you bought momentary instead of latching switches.

Yes you can solder directly to the pins, even though the pins are flat and the wire is round. The solder will wick in to the gaps and it will be fine.

You should indeed be using stranded wire. Single core wire is okay, but hard to work with sometimes. You can also use finer than 22awg as it is only taking a tiny current.

To stop the helping hands crushing the switch body try gripping the switch actuator. However, I noticed from the build instructions that the switches are installed in the panel before soldering. Wouldn't that help? You could hold the panel in place and solder all the switches.

For the actual soldering, get a soldering iron that works (a few watts should be sufficient) with a manageable tip size. Don't use lead-free solder, it's rubbish. Tin the wire by heating it with the iron and applying solder until a small amount covers the wire. Tin the switch leads in the same way, but work quickly so that the heat doesn't melt the switch housing. Then put the tinned wire next to the tinned pin, apply heat once again to both parts, and a little more solder. When the solder flows remove the heat and wait for everything to cool.

[ame]

Also, you are the second person I've seen on this forum who is building this same project. What are you doing about integration? I can't see any source code or wiring diagram for the Arduino on the blog or in the project's GitHub. ArdSimX is mentioned, but that is dead now. SimVim is its successor, but it works differently.

Yes, you could roll your own interface, and yes, you could use something other than an Arduino. So I am curious what you are going to do.

[Kaellis991]

I have been assuming that this layout map on SimVim has the necessary coding for that BendixKing transponder. The firmware via the SimVim plugin has been uploaded to the Arduino 2560 and is connected to Xplane.
I registered on simvim about two weeks ago. Just two days ago my registration was finally approved. So this weekend was the first time I have had a chance to ask questions on the forum. The first question is where do I start? So far no replies.

[ame]

Ok. Got it.

I'm not a fan of SimVim as it is not open source. However, I understand how it's supposed to work.

Basically, you need to review the hardware guide on the SimVim website and hook up your switches and LEDs to some pins on the Arduino (which is running the SimVim firmware). Then in the configurator, which is shown in the image you attached, you click on each element of the KT76C and select how you have connected it to the Arduino. On the list on the right you click on the specific pin you have used. That way, the configurator can produce a file that the Arduino will use, which contains a list of all the connected elements, what they are, and what pin they are connected to.

I can't remember the steps in detail, but basically, set up the pins, download the configuration to the Arduino, then automagically the buttons will work on X-Plane.

[Kaellis991]

I would like to use mobiflight, but it requires programming that is beyond my capabilities.
My goal is not to become a cockpit builder, I dont have the smarts for that but with some guidance I think I can get the SimvimCockpit to work.
Automatically....that is what I am hoping for.

[ame]

For hooking up the display you should follow this page:
https://simvim.com/svc_numbers.html

I suggest you use the Option: Direct Connection (about half way down).

For the switches, you need the following guide:
https://simvim.com/svc_inputs.html

Use the direct inputs (left hand diagram) at the top of the page. Connect the individual pushbuttons to an Arduino pin and GND. When the switch is pressed the pin is connected to GND so the Arduino can detect the state has changed.

The rotary switch can be hooked up in two ways, either as a bunch of switches connected to Arduino pins, or as a resistor network connected to a single analog pin. Both are described here:
https://simvim.com/tech_rotary.html

Again, you have to read and understand the SimVim documentation so that you know how SimVim is trying to implement these features. Then you choose the implementation you want, build it, then configure the software to match. Unfortunately it's a bit tedious, but no more than any other software.

[ame]

I would like to use mobiflight, but it requires programming that is beyond my capabilities.
My goal is not to become a cockpit builder, I dont have the smarts for that but with some guidance I think I can get the SimvimCockpit to work.
Automatically....that is what I am hoping for.

Programming is a state of mind. If you can follow a recipe in the kitchen you can understand program flow. If you can understand program flow you can make a program which flows as you wish.

MobiFlight is (or appears to be) open source, so I'd be happier recommending it.

I've put some hints for SimVim in another message. Good luck.

[Kaellis991]

Thanks for the SimVim hints. I have been reading through all of that for a couple of weeks. I understand the individual words, but when they are put together as they are on the website I get lost very easily. There is a lot of tech jargon that is written for those with an electronics background. Reading through those pages is indeed...to say the least...tedious. The reading and the understanding of those technical writings is many times mutually exclusive.

On the programming side over the last 25 years I've tried to learn Basic, Autolisp, C++, Python, and most recently working on Dynamo. None of it has ever "clicked".

[Joe Lavery]

Kirk,

Mobiflight doesn't require any real programming, You just have to work with the FSUIPC offsets. Many of these can be selected from a drop down list. You just need to read and follow the instructions.
For a simple introduction to just about every facet of the Mobiflight system, have a look at all the videos done by a young lad in the US, who calls himself "Captain Bob".
His intros will probably annoy you, but he explains the concept quite well, complete with all the offsets and setup data you'll need.

https://www.youtube.com/results?search_query=captain+bob+mobiflight

Joe

[ame]

Thanks for the SimVim hints. I have been reading through all of that for a couple of weeks. I understand the individual words, but when they are put together as they are on the website I get lost very easily. There is a lot of tech jargon that is written for those with an electronics background. Reading through those pages is indeed...to say the least...tedious. The reading and the understanding of those technical writings is many times mutually exclusive.

On the programming side over the last 25 years I've tried to learn Basic, Autolisp, C++, Python, and most recently working on Dynamo. None of it has ever "clicked".

Ok, well, the SimVim site does warn you that getting stuff to work is a long journey. I guess you're prepared for that.

You could start hooking up various parts on the bench, before you've built the instrument. Once you have the rat's nest of wires working you can install them neatly into the instrument housing.

I've had a bit of a play, and here's what I came up with so far:
For the MAX7219 LED module- click on a pin number in the list on the right, e.g. 30, a window pops up saying "Connect".
Choose "Connect 7 segment display". Defaults are ok (MAX7219 up to 8 digits), so click "Confirm".
I'm not sure how you drive a MAX7219 with a single pin, but maybe I'll look at the documentation again. Anyway, now pin 30 (or whatever) is attached to that display.
Now click on "XPDR Devices" and choose KT-76C.
Click on the right digits (XPDR_Code) and a pop up appears.
Click on 7-seg display
The pop-up says "select assigned display", so click on pin 30 (which you assigned above).
Another popup appears with an empty box and an arrow saying "<-- New entry". Click on the empty box.
I reckon you want no shift and no text, so the defaults are ok. Click Done.
Now click on the left digits (XPDR_FL) and do the same thing, but after clicking "<--New entry" I reckon you need to enter "4" in the shift position, to move the digits over by four places.
And that's it! I had forgotten how tedious the SimVim configurator was! Gag me with a spoon.

Buttons are the same, but you can click on a button on the transponder picture then click on a pin on the list on the right. Simples!

I suggest you try one thing, maybe a button, and get that working first- all the way from the physical button wired up to a pin on the Arduino through to the desired action happening in the simulator itself. Once you have one button working, everything else is gravy.

Ah, MAX7219:

The "CLK" input in this case should be connected to assigned controller pin (no need to use a pull-down resistor), other signal inputs (L,D) are the common for all output devices (pins #27,28).

So, CLK on the module connects to the assigned pin (pin 30 in the example above) then CS is connected to "L" which is pin 27 on the Arduino, and DIN is connected to "D" which is pin 28.

[Kaellis991]

Thank you for that much more descriptive explanation. You've filled many of the holes left open in The Simvim write ups. I have all the test boards to start wiring up those buttons and your directions have certainly helped clear up a few things.

[ame]

Thank you for that much more descriptive explanation. You've filled many of the holes left open in The Simvim write ups. I have all the test boards to start wiring up those buttons and your directions have certainly helped clear up a few things.

You're welcome. It's mostly guesswork, as I don't actually have any of the hardware. If you get stuck with it I'm happy to speculate wildly on possible causes and plausible solutions. Good luck.