Category: Hobbies

  • Timing concerns of delay line style memory

    Timing concerns of delay line style memory

    I was getting bent out of shape that I needed to somehow reconstruct the system clock out of the data stored inside a delay line. But fooling around with an old discrete delay line simulation in a circuit simulator by replacing the giant stack of flip flops with a proper length delay line shows that…

  • Audio Digital Delay with DRAM and Arduino

    Audio Digital Delay with DRAM and Arduino

    Aka “ADDDA” or “AuDiDeDrAr” or “aww dee dee drawer” or “A3DA” I’ve had this idea bouncing around in my head that you could use 1-bit wide DRAM as a delay line if you simply counted up through it’s addresses, reading and writing as you go. 1-bit wide DRAM like the M3764 have separate pins for…

  • National Semiconductor 4510 Mathematician

    National Semiconductor 4510 Mathematician

    I have a small collection of vintage calculators that I stumbled into collecting. I found one at a garage sale, and then one was given to me, then I found a neat one on eBay for a good price… Before I knew it, I was a calculator collector. I actually use most of them despite…

  • From the notebook: Tape Transports

    From the notebook: Tape Transports



    Todays notebook sketch is some ideas for building a tape “transport” – the mechanical bits that move the tape around in the right way and at the right tension. I have a weird fascination with magnetic storage media and tape in particular. It was a key technology in computing for decades and it has more…

  • Prototype Game of Life Synth Module



    Conway’s Game of Life (CGoL)has always fascinated me. It is probably the most well known of all cellular automata and also probably the most intuitive. Yet even simple patterns can turn into complex sequences of shapes, patterns, and noise. Years ago, when learning about the HTML5 WebAudio API, I came across a fun little demo…

  • Ray Diagram: Now with Measurements

    Ray Diagram: Now with Measurements



    I’ve continued to work on the optical ray diagram tool prototype. I added a way to measure the effective focal length (EFL) of the lens system. It isn’t automatic, but by adjusting the parameters you can align an intersection at the optical axis and read off the EFL. Obviously this should be a one button…

  • Early 90s Camera Teardown

    Early 90s Camera Teardown



    Over the weekend I tore down an old RCA Super8 camcorder. It came with a power supply but it had already been damaged in the past. The viewfinder showed text over static and the tape mechanism just made a horrible squealing sound. I was interested in perhaps using the imager somehow but it seems to…

  • Prototype Eurorack Frequency Modulation Synth Module

    Prototype Eurorack Frequency Modulation Synth Module

    I have a few prototype Eurorack modular synth modules in the works. I tend to get them working well enough to be musically interesting and then move to work on the next prototype. It’s not because I don’t plan on finishing them – it’s more that all the biggest questions are answered and I want…

  • Z80 Single Board Computer

    Z80 Single Board Computer

    Because the first assembly language I learned was for my TI graphing calculator, I’ve have a soft spot for the Z80 CPU. It’s a nice 8 bit architecture and widely used in pre-MSDOS machines. The Apple II used a 6502 but more or less all the “business class” machines ran CP/M on a Z80. It…

  • Analog meter synth module

    Analog meter synth module

    I haven’t shared much about my modular synth, but I really should. I’ve created several custom synth modules – even designing PCBs and custom 3D printed faceplates for them. The circuit design is also my own although heavily inspired by the very helpful synth DIY community. There’s only so many ways to build an Arduino-based…