Defender Update

Defender, the final panel layoutWell, the real work has now begun. I’ve ordered the front panel for Defender. It’s not changed much since the last picture I posted. The only real changes are the octave select buttons above the pitch and mod-wheel slots and it’s a little wider (30mm) so I have space to drill holes and mount it in it’s case.

For the case I’m going to aim for a monopoly/minimoog style case. wood with angled front panel. This gives some real benefits;

  • Nice ergonomics
  • Additional space for additional voice cards
  • Additional space for the wiring

I’m not sure if the front panel will be movable or not, I suspect not for the prototype due to the amount of wiring that’s going to be involved.

It’s not going to be a quick job this, here’s some scary figures ;

  • 29 Potentiometers, plus two pedal inputs
  • 84 Switches, yes, 84 of them!
  • 98 LEDs, that’s not counting the four dual 7 segment displays, which takes it up to 154 LEDs in total

Sometimes I wish we’d return to the days of programming like the DX7 and DW8000, it makes for a much cheaper and easier user interface to develop.

The other advantage of the sloped panel case is that it gives me more space for a bigger or additional supply, consider, 154 LEDs each drawing 20mA, this gives us over 3 amps of current just for LEDs! So there’s a real chance I’ll need a seperate power supply for the panel, luckily I have a spare 5V @ 5A switch-mode supply.

Next comes parts ordering, I’ve got the switches and most of the LEDs, but I’ll be needing a few more. Then the 4051 analogue demux chips for the front panel. The AVR only has 8 ADC inputs, and I have 31 inputs to read, the current plan is to use four 4051 chips and mux 4 of the ADC inputs to give me 32 ADC inputs in total. Then of course there’s the pots (I have a few) and also the knobs themselves.

Then comes the fun part, coding the panel handler on the micro, I can see a few long evenings and sleepless nights ahead of me with this project.

The ironic part about building a synth is that 90% of it is cheaper than buying an off the shelf one, the bit that’s really expensive, is the front panel. Defenders panel, including metal work, knobs, pots, switches and LED’s is going to be over 250 pounds! A single voice costs me around 40 pounds to build, including PCB manufacture.

I’m also dropping a couple of other projects to focus on Defender. This means I’ll only be working on the following projects (no particular order) ;

There’s enough there to keep me busy for the next few months. But, I want to get Defender into a condition where I can show it, even if it’s only monophonic for the time being.

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