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Gear panel tutorial, part 3b – Building a temporary panel

4 November, 2012

This is a small update to yesterday’s post. No programming at all this time!

I’ve built a quick and simple, temporary panel for the Gear Panel project. Breadboards are great for developing circuits, but it’s awkward trying to flip a toggle switch that’s floating on the end of a pair of wires. There’s the risk of accidentally disconnecting stuff while it’s powered up, which I assume could damage the Teensy. By mounting the components on a piece of MDF or plywood, we can use the system more comfortably while we test and develop it.

I should warn you. I love writing code, but I’m far less skilled when it comes to things made out of atoms. What I’ve made isn’t particularly wonderful. Quick and simple, remember? It is built with the stuff I found lying around the family garage. All I was looking for was a board I could drill holes in and attach the switch and LEDs to, and some way of keeping it off the desk and attached to the Teensy breadboard. This isn’t intended as a ‘production’-standard piece of hardware, but a workbench tool.

I got a big sheet of 4mm MDF from the local hardware shop, and cut a panel to fit a convenient cardboard box. I used nails held in place with hot glue to locate the panel into the box. (Only because I had nails right there on the countertop in a little box, I didn’t want to dig through the junk to find dowels or bolts.) I drilled a few holes into an offcut to find out which diameter drill bits I needed for the LEDS and for the toggle switch. Then I used those holes as a jig, to hold the LEDs in place while I soldered on the leads.

I connected the cathodes of the LEDs together so I could use a single return pin. I found my heatshrink too narrow to go over two wires so I couldn’t insulate those joins, unfortunately. The six LED anodes I connected to a strip of header pins, and the cathode got a single pin. I used header pins to easily and reliably connect back to the breadboard; for a permanent project I’d just solder the wires directly to the stripboard or PCB. Header pins reduce the number of loose wires floating around your project – always a bonus!

Perhaps I’m a little OCD, but I didn’t want to drill holes randomly into the final board, even if it is just a workbench tool. I needed to create a template. As with most problems in life, this was solved by using a spreadsheet:

Adjusting the width and height of the columns was the easiest and quickest way of getting a piece of paper with nice symmetrically- spaced marks. I used the offcut again to practice drilling through the template – I needed practice getting the drill aligned.

I would use a hot glue gun to permanently mount and protect the LEDs, but the 5mm hole holds them firmly enough for now.

I have a confession. I lied when I said there was no programming. But it was only to change the pin numbers! This is what my breadboard looks like now:

I had to butcher the cardboard box slightly to get the breadboard to fit inside it. The final touch was an assault with a Dymo labeller.

Now it’s much easier to move the gear switch, and to see or feel what position the gear is supposed to be in. And the big empty space on the remaining 90% of the board is crying out to be filled with more useful switches, buttons, potentiometers, servos… watch this space.

  1. john permalink

    Awesome stuff! I am a student pilot and started using x-plane on my macbook to help me get use to checklists and memorization. I’m thinking about doing something like this to make a replica of the cessna 172 lower panel with the switches. Would this be hard for someone with little to no programming experience?? Thanks and again nice work

    • I’d be happy to help with the programming of course :-)

      It should be straightforward. Wiring a hardware switch to a simulated switch is rarely complicated, and the Cessna 172’s panel doesn’t contain any huge surprises.

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