DrBunsen's House Of Sparks and Noxious Odours

Here will be detailed ongoing hacks and stuff, including the PizzaPlayer[tm], various G3/6100 projects, rackmounted 1U B&W/G4, compact upgrades inc PCC, programming, Psion 5mx/Ericsson MC218 stuff, anything audio, MIDI, PIC and DSP related, paint and dye experiments, recasings, MacQuaria etc etc etc

Hack on!



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First things first, I'm building a large (9x12x4) steel shelving bay for storage. Things are no doubt a lot easier to build when you know where all your parts are...

dankephoto's picture

see the tab called "edit".

dan k

For the longest time, I never noticed that the edit link for first posts was at the top. I was so used to looking for "edit" on the bottom. I'm glad to see that I'm not the only person to have been deceived by the top "edit" tab. Wink

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Still building shelves...

I'm putting a little plan together for a simple 16 step drum trigger sequencer, either on the Psion using a serial port multiplex IO board, or on a PIC using code from the MIDIbox project at ucapps.de

Drum trigger - puts out a voltage pulse to trigger some analogue drum synth voice boards I have lying around. The voltage will be +5, +10 or +12 depending on what I'm building for.

Idea being a simple-ish (post "Hello World!" stage) exercise in GUI, real-time and control programming, which can be expanded or recycled for other projects in the future.

Basic rundown:

  • Read DIN sync on two input pins as a timing reference.
  • Cycle through 16 steps. If the user has defined a note as "on" for that step, send pulse out another line.
  • Repeat.

Psion version: GUI of 16 blocks arranged horizontally across the screen. Tapping a block switches it off or on.

PIC version: Interface consists of 16 LEDs and buttons.

Read more

I wish I still had my Amstrad Notepad, that had a parallel port and BBC Basic in ROM...

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Put out a call to other Psionauts.

Shelves built.

Made backups of my Documents and Systems folder to a 16MB CF card. Transferred those to the Mac via cheap-ass USB multicard reader (OS X only for some reason). Transferred some .sis installers to the Psion and installed them.

Got 512MB CF for Linux. Just need to work out how to make a complete image backup of the C: Drive before I try it.

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Just scored a $12 iMac 233 with a spare motherboard and processor. I'll be wandering around the workshop area with that motherboard soon, waving it at various cases and seeing if I can make it fit.

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Oh, and a 9" VGA -colour- CRT, heh heh heh.

Jon's picture

Oh, is the neck short enough to fit it in a compact Mac case? Biggrin

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I'll know that when I pick it up.

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Collating some of my older hack ramblings here.

PizzaPlayer: 6100 based rackmount audio FX unit/sampler/synthesizer
Universal Boot Disk: one disk to rule them all
X11, XPF, MacOnLinux: ideas for a tri-boot *nix/OS X/MacOS dual processor 9500
1400 second battery: left and right batteries in a 1400?
Mac monitor out to PAL/NTSC
6100 cooling and overclocking
Slim keyboard & Display: minimum footprint peripherals for the PizzaPlayer
Duo keyboard to ADB: more of the above
Inverting display: inc link to Pivot software
6500 subwoofer in PCC: with an LCD there might just be room Smile

Old Forums: Index and Search

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Jon wrote:
Oh, is the neck short enough to fit it in a compact Mac case? Biggrin

Damn. No. I haven't decased it yet, but in the existing casing it's about 2" too long. I'm considering making a moulded plastic rear for it, and making it look like some bastard iMac/compact chimera. Or just slicing up another compact case to make a 2" full-height extension at the rear. That would give me more room for the motherboard, power supplies, drives, etc.

Mind you, I haven't put it up against the CC yet Smile

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Dug up some useful info online for hacking my Simmons drums, including full schematics for the SDSV and chip data sheets for that and the SDS-8. There's an unimplemented resonance control on pin 10 of the SSM filter chip in the -8: from the schems looks as simple as bypassing one resistor with a pot.

I picked up a pile of voice boards for the V a while back, without the chassis. The chassis supplies a backplane connector to each voice for trigger signals, power and audio out, and routes to a mixer and individual outs. The plan is to rig up a simple PS and trig socket for the connector on one board and get that running, then investigate further mods: starting with replacing the trimpots for the "memory" voices with real pots.


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Accented triggering from digital pins - accent track triggers a global voltage boost to all pins via a separate pin and a transistor or relay or something.

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2 bit DAC using resistor ladder a la AOUT_LC.
8 bit DAC IC.

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Electronic Design on a budget
Python and VOIP on the Nintendo DS
TSlots - modular extruded aluminium construction system

Jon's picture

My father in law does the aluminum extrusion stuff. If anyone is interested he can do custom designs. He built a tower for someone at the University of Kansas recently. He's one of the best mailing sorting and folding machine repair techs in the area, too. Smile Also, he travels a lot for the repairs, so he's through Missouri, Iowa, Nebraska, Kansas, etc. often.


Oh, and if anyone calls their number you're likely to either talk to him or my wife. Say "hi" for me. Wink

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PSP external battery pack and charger

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Parallax Propellor - 8 x 80 MHz 32 bit parallel cores on one cheap microcontroller.

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Battery Soldering - includes building your own spot welder

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SD/MMC on WRT54G using floppy connector as card edge connector

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Australian Power Assist and E-bike links
massive DIY amp project gallery - pocket tube headphone amps for example. mini power supplies and other stuff

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DrBunsen wrote:

Slim keyboard & Display: minimum footprint peripherals for the PizzaPlayer
Duo keyboard to ADB: more of the above

Well here's a laptop keyboard on a PS/2 controller, so this at least looks possible.

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ok. code tags at the start and end of every line work. Sort of. Multiple spaces are reduced to one. Oh for a Preview button.

Duo Dock connector Pinout from the great pinouts.ru

Of interest:


.1 2 77-79....PR +24V EXT........Raw +24V from AC adapter
.12 29 42.....+5V MAIN OUT.......+5V regulated power
.63...........SERVEE.............-5V for SCC transceivers
.67...........+8V SOUND.........."clean" +8V for sound output
.68/70........+5V MODEM/SOUND....+5V power for modem/sound
122...........+5VEXTSENSE........+5V external sense

.40...........IOCLK..............15.6672 MHz I/O clock

.72...........SND OUT L..........Sound output left
.73...........EXT MIC FILT R.....Right in from ext mic
.74...........EXT MIC FILT L.....Left " " " "
148...........EXT MIC SEL........External microphone plugged in

.83...........ADB DATA...........ADB data
.84........../ADBPWRON............". power-on key
.95...........CPUCLK.............CPU bus clock
114........../SLOT IN............Expansion device plugged in grounds pin
137........../SWIM CS............SWIM chip select
138........../SLOT E IRQ.........Pseudo-NuBus expansion slot E interrupt
139........../PFW................Power fail warning (shutdown bit)

not shown........................guess

..6 16-18 55 60 82 85 136 150
.71..............................Sound output right?

Note: / = Active low

Connector: JAE part number JX20-152BA-D1LTH

... giving the Duo Dock direct access to the microprocessor's 32-bit address bus, 32-bit data bus, and control signals

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  • Use/make a 2MB card with identical chips to the existing ones
  • Solder it directly to the pads
  • Piggy back identical VRAM chips onto the existing ones and fly only the necessary lines to the pads
  • Replace the existing chips with 2x 2MB (32Mb) parts
  • Buy a 4MB mobo and study the differences
  • Hack a cheap 14" VGA LCD into the bezel, using the VGA out on the 'book

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Japanese mods - iMac pinouts woohoo. iMacs in LCs and tiny thin client-like cases, SE/40, shrunken LCs, second SIMM slot on LCs, imitation Cassie/Happy Hacking keyboards. Mind bending Google translation.

StarTTY - turns any text terminal capable device into a configurable online information kiosk/display.

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Free samples of electronic components, enclosures etc - where to get them and how.

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A whole bunch of pinouts including some of the really obscure Apple ones.

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Mini-PCI to PCI adapters amongst other things from http://www.costronic.com.tw/

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This article at hardmac *claims* it has the complete pinouts and conversions for an iMac DV ATX mod, but I can't get to the last page to find the pdf. Bugger. Archive.org ain't helping either.

Jon's picture

I was able to open the last page, and got the .pdfs, and I used the FF "Save Page" feature to create a local copy of the third page. Let me know if you still need them, and I can send them your way.

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The overclocking hacker's best friend - square wave oscillators with variable frequencies.

LTC6903 1kHz-68MHz Serial Port Programmable Oscillator


  • 1kHz to 68MHz Square Wave Output
  • Frequency Error less than 1.1%, 0.5% typical
  • 0.1% Resolution
  • 2.7V to 5.5V
  • SPI (LTC6903) or I²C (LTC6904) Serial Interface
  • no external components other than a power supply bypass capacitor


  • Precision Digitally Controlled Oscillator
  • Power Management
  • Direct Digital Frequency Synthesis (DDS) Replacement
  • Replacement for DAC and VCO
  • Switched Capacitor Filter Clock

So that will OC every 68k Mac fairly handily. Imagine a self-clocking Mac, software controlling its own clock via the serial port.

And for anything faster, there's:

LTC6905 17MHz-170MHz Resistor Set Oscillator


  • One External Resistor Sets the Frequency
  • 17MHz to 170MHz ±0.5% Typ
  • 2.7V to 5.5V Supply

Which takes care of anything up to the last series of G4s. Add a pot - dial a frequency!

And those two little magical words - "Request Samples"

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The shelving and workbench is complete. Everything is up off the floor and on shelves awaiting sortage. Two bays, one 2.4m high 2.4m long and 0.86m deep, one 3x2.8x0.9. Photos to follow.

Now on the hunt for an oscilloscope and soldering station.

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I just discovered that LightSoft's 68k/PPC Assembly workshop is free and open source as per 2003... It's amazing!


Their docs page looks nice as well - ADB programming... fancy that!



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Don't forget to hunt down that serial in to 12 PWM outs IC.

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Simple PC Data capture addon for analogue oscilloscopes.

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DrBunsen wrote:
...hacking my Simmons drums... SDSV ... and the SDS-8.

...voice boards for the V ... without the chassis.

... starting with replacing the trimpots [on the 8] with real pots.

Just ordered a +/-15V DC power supply that'll fit in 3U, for the V boards.

A thought: small slider pots on the SDS-8 should fit beside the existing knobs without finger interference.

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AndrewMartens wrote:
While working on my MBHP SID project / I started looking into some hybrid digital/analog synth projects./

Using SSM and CEM chips makes designing analog circuitry easier, but there's not many of them to go around. Fortunately, there exists the LM13700 OTA (operational transconductance amplifier). There are some simple circuits out there (for example, the 13700 datasheet) that illustrate how to use half of one chip as a VCA. One 13700 can also be used at a 12 dB (2-pole) filter - chain two of them for a 24 dB filter!

If one searches Google for "Juergen Haible Wasp Filter Clone", you'll find a clone of the filter section from the Wasp. I'm planning to swap out the no-longer-available CA3080s with a 13700 filter section.


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Now this is interesting: this fellow has built himself a SCSI RAM-disk and a SCSI PCMCIA drive from scratch, using AVR microcontrollers. I wonder if this could be a starting point for further SCSI-to-X hacking.

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That is so cool. SCSI ramdisk, I could have used one of those on my 6100 Biggrin

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I have also found some very nice ASK modulated chips that could be used for extending a ComLynx like communication to wireless connectivity. This would be baud-rate independent up to around 62000 bauds.

These chips are used in remote keys for cars.



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Comrades, the Central Committee of the Colour Classic Carnage Project is proud to present the glorious Five Year Plan:

  • Beige G3 motherboard laying flat sideways in custom tray
  • 10.4" LCD with ebay VGA controller board or:
  • 8.4" VGA/AV LCD TV
  • G4 ZIF @ 466MHz
  • 768 MB RAM
  • ATX power supply from a 1U rack server or a MiniITX DC-DC board
  • Slot loading DVD from an iMac or 'Book
  • Performa TV/AV board (and FM if I can find it) on PERCH hack
  • 2 x 2.5" laptop drives in a RAID
  • USB/Firewire
  • External plug for original floppy drive
  • Harman Kardon stereo speakers from an iMac
  • Subwoofer (possibly internal)
  • Integrated UPS/battery power

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AV Digitizer Options v.1.0b1

Download the file called "Plug-in_Digitizer11.hqx"

Thanks to tmtomh in this thread