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• DRAM modules

  Keith • 03/03/2024 at 14:37 • 0 comments

  I have a large stock (132 pieces) of 72-pin SIMM packaged DRAM modules. Some PC service engineer probably kept them thinking they would be useful, then technology moved on and PCs no longer used them. 

  However, they are likely to be 5V and potentially useful to retro computer builders who want more RAM than a few SRAM chips can provide. They certainly save a lot of wiring. 

  Let me know if you have any idea what they might be used for. 

  The 32-bit wide data bus might be useful for video frame buffers. An MC6845 CRTC could fetch four bytes at a time instead of one, thereby quadrupling the horizontal pixel resolution. 

  I don't have the time to sort them out by memory size, I have one labelled 8 MB (2M x 32-bit) and the rest are unlabelled, but if you need a particular size I could have a look for one.

  I also have sixty-six 30-pin SIMMS, such as 1M x 9 or 4M x 9 bits. These are only byte-wide data but the connections are on 0.1" pitch and thus easier for connecting to prototyping board.

• Peltier dehumidifier

  Keith • 09/18/2022 at 21:56 • 0 comments

  A Peltier with a heat sink on each side. A fan cools the hot side and the cold side drips condensation.

  Here is the hot side:

  Here is the cold side:

• DC servo motor

  Keith • 09/17/2022 at 22:51 • 0 comments

  Some of my neighbours left a treadmill in the recycling area. The council do not deal with anything more than mixed cardboard, paper, plastic bottles and compostable waste.

  Armed with a powered screwdriver, I dismantled it and took the steel to the scrapyard. Some electronics went to e-waste but there was a massive DC servo motor and I know how expensive those things are.

• Integrated circuits

  Keith • 09/17/2022 at 21:58 • 0 comments

  ...

• Stepper motors

  Keith • 09/16/2022 at 00:31 • 0 comments

  Mitsumi Stepper motor M68SP-3

  12V 48R = 0.25A, 3W. 1.8 °/step.

  Connections look like unipolar

  1 brown
  2 black
  3 orange
  4 yellow
  5 red (common to 1 and 2)
  6 red (common to 3 and 4)

  I think it came out of a 3.5" floppy drive, for positioning the head.

  Other motors

  Four large one are from a very old line printer. Flat ones from 5.25" floppy drives.

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