The XenoLab

I've tried to do some serious data mining to dig forward how the different electronics in Xenon Disco was built. I have a bunch of PCB layouts that we used, sketches, etc, but sadly enough the component placing diagrams seems to have been lost to most of them.

Here's however a peek into what the "XenoLab" worked with:

LEC-320 MUX PCB (c) P.Sandstrom

This is the silk screen for the LEC-320 MUX . It feaures ...

  • The multiplexer unit with latches, logic and opto decoupling
  • Two A/D converters with LP filters for the music control
  • Strobe control output

... so it was basically the final "all in one" -solution that held the most used and most important electronics that was developed and tried out using "Diabolic Box" over the years. Looks like it was made on christmas eve 1996 !

Early stroboscope schematic (c) J.Åkerback


Our stroboscopes were designed according to this draft. We built two of them, bigger capacitors were added later and the resistors that limits the current while charging were also replaced with smaller values. This way we cranked up the brightness to a acceptable level (= making 'tau' smaller). Seemed that we couldn't get more "juice" out from this design, to improve it we would have had to charge the caps with higher voltage.
Early stroboscope control unit schematic (c) J.Åkerback


This exposes our early ideas on how to make the strobes flash in a nice and controlled manour. 1) HI and LO pass filters (with a master gain control) that generated pulses that trigged the strobes on the music. 2) a 555 timer circuit that trigged the strobes. In a more mature version of the control unit we had a master and a slave pulsegenerator, the master was running slower (e.g. 1.5 seconds) and generated the intervals of flash-bursts. The frequency of the bursts was generated by the slave and was high (e.g. 5Hz). Of course that resulted in 1.5 seconds of 5Hz flashes, 1,5 seconds of no flashes and so on.
A/D Converter PCB ?


I'm not quite sure but this resembes the A/D converter used to convert the bass beats in the music to pulses. The music came in to a pre amp with a lowpass filter and then moved on to a optocoupler (yes, we did have a lot of problems with floating grounds and strange voltage potentials on gigs as the wiring at the places we played wasn't always very good. That's why optocouplers is used in so many designs - our stuff went into the great semiconductor heaven on a regular basis otherwise). It was the computer who did the actual A/D conversion. We used the paddle-inputs of the commodores which basically reads the resistance from a potentiometer (using current if I remember correctly), and the potentiometer was the optocoupler.

Relay driver / control circuit draft (c) P.Sandström


I found a lot of discarded 12V relays at the scrapyard in Vasa and thought that they might come in handy. They seemed to have been used in some kind of telecommunications equipment. I thought that it would be a nice idea to use them for controlling some low voltage light effects we had. So above is the draft for the PCB which allows a commodore to drive the relays. They also made a cunning clicking sound when they ran, controlled by the light sequencer.

Relay driver / control circuit PCB (c) P.Sandström


Above is the final (manually taped) PCB. The whole shebang was fitted in an old case which I think had held the electronics for a discarded TTY-terminal. Looked quite cool.

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