Electronics

Belying my education as an electrical engineer, I have done little in the way of my own commercial electronic circuit design, be it analog or digital. (While I was at Cadence Design Systems I did have quite a bit of exposure to some cool designs, though.) I do tend to tinker quite often with various electronic projects. Over the years, I’ve done some strange and bizarre things:

Voyetra Eight

My biggest project at present is restoring and repairing my Octave-Plateau Electronics International (OEI) Voyetra Eight analog synthesizer and its VPK-5 5-octave controller keyboard. It’s such a big project, it has its own website.

PC Engine Greenhouse

Probably my most famous and ambitious project, the PC Engine Greenhouse is/was an attempt to provide a programmable “brick” to help develop new games for your PC Engine / TurboGrafx-16 / Duo.

The Greenhouse (as it affectionately came to be known) started off as a hack of the standard Xilinx XC4000 protoboard. This version had 2 megabits of battery-backed SRAM, and was capable of playing back basic trial images (such as the CD-ROM System 2.0 card.) It also had a HuCard slot for reading images as well.

The Greenhouse v2 was a project to manufacture 25 of the Greenhouse units with some improved specs, including 8 megabits of SRAM, a faster parallel port interface, a self-contained battery system, and would be based off of the less-expensive XC3000 chip. 18 months of on-and-off development time went into the Greenhouse v2, including a custom PCB and lots of hardware hacking. In the end, I was unable to devote any more time to the project, and it has been put on indefinite hold. Those individuals who contributed a small sum towards its creation were fully reimbursed. In the event that I’m able to locate time to complete its development (which will require etching a new set of double-sided PCBs), an announcement will be posted here as well as on the Turbo Mailing List.

Various & Sundry Projects

Over the years, I’ve worked on some interesting other mini-projects, such as an SCA receiver (a sideband on your FM dial), various interfaces to my old Apple //e (such as thermocouples, D/A converters, and LEGOs, before the advent of Mindstorms), my very own VCR “Rabbit” (my first etch-my-own PCB project!), and even turning my Timex Sinclair 1000 into a home lighting controller! (I’ll try and post schematics of this sometime . . . it mainly involves the 16KB memory port and a few SCRs . . .

7 thoughts on “Electronics

  1. Hello Joan,
    Great to find your site and your info on the Voyetra – The LDC initials on the circuit boards
    belong to me – I did all the board layouts for the machine in the early 80’s working
    with Carmine(hardware) and Bruce(software) I knew at the time it was a machine ahead of it’s time. I have one now that is working fine and I love seeing your passion in restoring yours. Just wanted to say hi – your entire site is fun.
    Lance

  2. Hi Joan,

    Thanks for hosting the Voyetra 8 info. I recently created what I call the Simplified Guide to the Voyetra 8, and would be happy to share it with you and others if you would like to add it to your Voyetra 8 page. It’s a 127k PDF file summarizing the V8 procedures along with illustrations. Email me if you would like to host the file.

    Thanks,
    Jered

  3. Hi Joan,

    Thanks very much for your Voyetra-8 documents. I’m having some trouble tracking down some issues with my Rev4. I can’t get STORE to work, and I’ve checked obvious things like the memory protect switch. I even tried to clean up the solder joints on both the memory protect switch and the STORE button. When I had the V8 open, I got a patch to store once, but it’s hard for me to figure out what’s going on. Any ideas?

    I’d love to get this thing fully tuned up and serviced, but I worry about shipping it across the country. And then there’s the cost. :-)

    Anyway, I’m glad to see your work on the Internet keeping these awesome synthesizers alive.

  4. Hi Tom,

    The most frequent source of failure on these devices is the backplane. Try removing and reseating every card. After you reseat them, wiggle them side to side to ensure the connections are stable. Also double-check any ribbon cable connections.

    It may be that the scanner for the front panel is missing that switch due to a bad line. I don’t have the schematics in front of me so I’ll have to get back to you on this.

  5. Hi Joan,

    I’m just starting to restore an old Voyetra-8, and I’m very happy to find your page on the machine! Thank you! if you have any information on a forum or on some people to contact to share information, I’m really interested! Patrick

  6. hi joan,
    thanks a lot for your collection of files about the voyetra eight, its a really great ressource!
    ive been searching a V8 for quite a while, now if have the chance to buy a rev4 which seem to have some minor (?) issues. thats why im looking now for every bit of technical information about it, especially some schematics…
    there is a yahoo group about the voyetra (if your not already a member it would be great to see you there), would it be ok for you if we save your files there as well?
    and do you still have the contact to lance who posted here, i think he may be a great source of information about the synth as well.
    the v8 is a really amazing synth, it would be great if we could help peoples to keep it alive!
    thanks and stay tuned
    kris

  7. Joan,

    I’m wondering if you’re the same Joan who posted in 1999 about acquiring a couple of Sun 1’s. If so can you drop me a line… I’m in the middle of a Sun 1 restoration and am wondering what happened to the units (and if you have info/docs that you can share…)

    Thanks.

    Earl

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