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My new button box design


Braeden108

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I thought I'd put together a little post showing my new design for a button box I've been making.

 

A while back, like a year ago, I bought some switches for a box but I never got around to assembly. Which is good because it's given me some time to put together some ideas about how to do it right.

 

I think the biggest feature of this design is the interchangeable top plate. The idea there is I can make a text panel that is specific to each aircraft and swap it when I switch aircraft.

 

I'm an EE student so I also went ahead and designed my own PCB to run the box, its basically a copy of the PCB included in the MMJOY folder, but it incorporates resistors on each switch. I also put a 555 PWM circuit on it so I can dim the backlighting LEDs.

 

I've finished machining on the plate that holds the switches, soon I'll have the PCBs made and laser cut the top panels. After that comes the hard part of manufacturing the axis lever which I plan to use for radar elevation in the M2000. Actually, upon writing this post, I may go with a wheel instead. It would be much easier to manufacture. Lastly I plan to lathe up some switch caps for my locking lever switches. I based them off of the switches that are in the B-1 Lancer. As much as I love the TL series that are in the A-10 and others, I thought these looked a lot cooler. It also gives me an excuse to knurl something.

 

If anyone's interested in the CAD files or board schematics I'll gladly send them over.

 

Anyhow, I'll keep you up to date on my progress. Mostly as motivation for me to finish the box this time :D

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Light the tires kick the fires!

 

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  • 3 weeks later...
  • 2 weeks later...

I got my first PCB sent to me today, I'm super excited because it turned out great. We'll see if it works.

 

I also got a good start on soldering all the wires to my switches. I thought it looked funny when I held them all up like a very very expensive bouquet.

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Light the tires kick the fires!

 

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I have had this same interesting question about this. I never thought to google it but till I saw your question so I found this which makes it sounds pretty darn close. I am no electronic guru I usually copy other peoples design but I found this on here and poster down below asked the question! with a lower post for the answer. Maybe Braeden has a better answer.

 

http://www.learningaboutelectronics.com/Articles/Shift-register-circuit.php

 

"These pins only move data when they transition from LOW (0) to HIGH (1). If these pin are already in a HIGH state and they are sent a HIGH clock signal then nothing happens, the pin 11 and/or 12 in a HIGH state will require two actions and must first transition to a LOW state, then transition to a HIGH state to put data into the register or storage register. "

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Why resistors on the switches?

 

Thank you

I think your referring to the resistors on the board? I'm the same as Brewnix in this instance I copied a design I saw on SimHQ and then put a 555 pwm circuit for my back lighting dimmer.

 

Anyhow, those resistors are pull up resistors. I'll start with the example of what would happen if it weren't there. Let's say the switch is closed, the shift register will see 0 volts at the switch because it is closed and any voltage that is on the switch will have gone to ground. This is a good thing. Now when the switch is open there's no path to ground but there's also no voltage. So the voltage there could be anything. That's called floating. If we put a resistor on there we can ensure that it has voltage there when the switch is open. And because it uses a relatively high resistance the voltage can still go "0" when the switch is closed because there's a direct path to ground and the current thought the resistor would be small. Like pouring water into a bucket with no bottom.

Light the tires kick the fires!

 

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I have had this same interesting question about this. I never thought to google it but till I saw your question so I found this which makes it sounds pretty darn close. I am no electronic guru I usually copy other peoples design but I found this on here and poster down below asked the question! with a lower post for the answer. Maybe Braeden has a better answer.

 

http://www.learningaboutelectronics.com/Articles/Shift-register-circuit.php

 

That's a good explanation of how a shift register works, they were confusing as hell w

 

"These pins only move data when they transition from LOW (0) to HIGH (1). If these pin are already in a HIGH state and they are sent a HIGH clock signal then nothing happens, the pin 11 and/or 12 in a HIGH state will require two actions and must first transition to a LOW state, then transition to a HIGH state to put data into the register or storage register. "

That's a good explanation of how a shift register works, they were confusing as hell when I first learned about them.

Light the tires kick the fires!

 

[sIGPIC][/sIGPIC]

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  • 2 weeks later...

It verks! I was worried while assembling it that I'd missed something in the design. Even though I sat on the design for a month and checked it over periodically.

 

I used solder paste and a hot air soldering system to mount all the components. During assembly I in my infinite wisdom soldered 3 of the shift registers on backwards. To find this out I had to desolder the arduino because I didn't know if it was working. As it wouldn't light up when plugged in. Of course there was a short between VCC and GND which was the reason it didn't light up. The desoldering heat actually warped the board :D but no matter.

 

The pwm circuit works too. Though probing it with my new scope (best xmas ever) showed that the circuit doesn't modulate the duty cycle instead it modulates the frequency. So I don't get a great range of brightness out of my back lighting. But I think I can look at live with that. Though this may have to do with capacitor values within the circuit so, maybe I can fix it.

 

Next up, attaching the switches. Then etching the panel.

IMG_20181226_204340.thumb.jpg.d4949a8e12dc862a1408f6ba54d09ea0.jpg

Light the tires kick the fires!

 

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It verks! I was worried while assembling it that I'd missed something in the design. Even though I sat on the design for a month and checked it over periodically.

 

I used solder paste and a hot air soldering system to mount all the components. During assembly I in my infinite wisdom soldered 3 of the shift registers on backwards. To find this out I had to desolder the arduino because I didn't know if it was working. As it wouldn't light up when plugged in. Of course there was a short between VCC and GND which was the reason it didn't light up. The desoldering heat actually warped the board :D but no matter.

 

The pwm circuit works too. Though probing it with my new scope (best xmas ever) showed that the circuit doesn't modulate the duty cycle instead it modulates the frequency. So I don't get a great range of brightness out of my back lighting. But I think I can look at live with that. Though this may have to do with capacitor values within the circuit so, maybe I can fix it.

 

Next up, attaching the switches. Then etching the panel.

 

 

Nice work!! Can you use sockets for promicro and shift reg? Just so I can remove them and not worry about having to desolder.


Edited by Brewnix

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Nice work!! Can you use sockets for promicro and shift reg? Just so I can remove them and not worry about having to desolder.

 

Certainly, though I'm not aware of sockets for SMD components. If you wanted sockets you'd have to switch to DIP to use a socket. Then you could use some female headers for the promicro. I didn't because I need this to be as short as possible.

Light the tires kick the fires!

 

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