Jeff Duntemann's Technology Projects 
1979: The COSMAC IMP (Inexpensive Matrix Printer.) I designed and built a simple thermal printer for the COSMAC ELF computer, using all COSMAC parts and a little OEM printhead from TI. I offered the circuit as a project article to Popular Electronics (which had published the ELF in 1976) but PE said the Elf's time had passed.
1979: The COSMAC IMP (Inexpensive Matrix Printer.) I designed and built a simple thermal printer for the COSMAC ELF computer, using all COSMAC parts and a little OEM printhead from TI. I offered the circuit as a project article to Popular Electronics (which had published the ELF in 1976) but PE said the Elf's time had passed.
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1979: A top view of the IMP's circuitry.
1979: A top view of the IMP's circuitry.
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1979: My first true home computer, an Intersystems DPS-1 S-100 mainframe with a 1 MHz (!!) 8080 CPU, 32K RAM, a pair of DS/DD 8" diskette drives, and several I/O ports. The large-screen display worked well with WordStar, and the Diablo daisy-wheel printer gave me letter-quality output. The lashup atop the DPS-1 was a stepper motor driven through TO-3 switching transistors from a parallel port on the computer.
1979: My first true home computer, an Intersystems DPS-1 S-100 mainframe with a 1 MHz (!!) 8080 CPU, 32K RAM, a pair of DS/DD 8" diskette drives, and several I/O ports. The large-screen display worked well with WordStar, and the Diablo daisy-wheel printer gave me letter-quality output. The lashup atop the DPS-1 was a stepper motor driven through TO-3 switching transistors from a parallel port on the computer.
Viewed: 5852 times.

1982: This is my electronics bench/ham shack in Rochester, NY. I put it next to the cold water entry and had a really good earth ground for radio work. It was, of course, a horrible mess at all times.
1982: This is my electronics bench/ham shack in Rochester, NY. I put it next to the cold water entry and had a really good earth ground for radio work. It was, of course, a horrible mess at all times.
Viewed: 7525 times.

1990: I built a 3V4 BCB regen out of Harry Zarchy's book Using Electronics. Good for BCB; not enough gain for SW.
1990: I built a 3V4 BCB regen out of Harry Zarchy's book Using Electronics. Good for BCB; not enough gain for SW.
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1990: Bottom view of the Zarchy 3V4 regen.
1990: Bottom view of the Zarchy 3V4 regen.
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1992: A general-purpose audio amplifier for test purposes, based on the LM386 half-watt amplifier IC. It's basically an audio signal tracer, and I use it to amplify audio generated by receiver lashups that lack audio sections.
1992: A general-purpose audio amplifier for test purposes, based on the LM386 half-watt amplifier IC. It's basically an audio signal tracer, and I use it to amplify audio generated by receiver lashups that lack audio sections.
Viewed: 5174 times.

Inside view of the LM386 audio amp. I don't know what the plastic box was originally for, but it had a speaker in it and I got it for a dollar at the Flagstaff hamfest.
Inside view of the LM386 audio amp. I don't know what the plastic box was originally for, but it had a speaker in it and I got it for a dollar at the Flagstaff hamfest.
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11/95: George Ewing and I in my Arizona garage/workshop/ham shack, which I had designed and recently completed. It was heavily insulated and air conditioned, with a 2" conduit for antenna cabling to the roof, and 220V for my lathe.
11/95: George Ewing and I in my Arizona garage/workshop/ham shack, which I had designed and recently completed. It was heavily insulated and air conditioned, with a 2" conduit for antenna cabling to the roof, and 220V for my lathe.
Viewed: 7027 times.

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