Building a radio (Part 5) - control panel

Emboldened by success with the loudspeaker mounting I set to work on a panel to mount the control components - a button, volume control and display. I was going to follow the same process as before: cut a crude shape in the top of the box then fit a nicely-shaped panel on the top. I started putting something together in TinkerCAD (I can really recommend it; the program runs within a browser and is very easy to use) that I could feed to the 3D printer. It was easy to create space for the button and volume knob as they have threads and nuts for fitting directly into circular holes. The volume control is actually part of the amplifier and the length of the thread is small so I needed to make sure that the panel was thin in that section so everything would fit together.

The display was more complicated. The display is mounted on its own circuit board and has a ‘backpack’ beneath it. The backpack is a mini-board linked to four pins for easy control, much simpler than wiring the whole display up and controlling it ‘raw.’ That’s all great, but I couldn’t find any diagrams giving the exact dimensions. And as it’s a 3D object itself I couldn’t just create a space and expect it to fit. I needed:

• To make sure that just the actual LED display part was visible
• The display surround isn’t level throughout - one side is raised and hides the LED backlight. So the support will need to accommodate this or the display will flop about rather than sit securely
• To make sure that the top of the display part was level with the panel I was designing, not awkwardly sticking up above or below the rest
• To make sure that the supporting board and backpack weren’t going to be fouled by either the panel I was designing or the wooden case itself I then realised that there was a problem with the volume control. If I just made a hole for it, the entire amplifier assembly would spin around when I tried to change the volume until they ripped their cables free from everything else. So I had to add a small post that the amplifier could rest against that would keep it in place.

That’s a lot of things to get right without presice measurements. It took three attempts to produce something that would work but eventually I had something I could install. Is this really the last hurdle? Can I assemble everything for a proper test? These questions aren’t a prelude to ‘tune in next time…’ (but please do) but serious questions I was asking myself!

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See also:

• Building a radio (Part 6) - the whole shebang
• Building a radio (Part 4) - loudspeaker mounting
• Building a radio (Part 3) - noise reduction