Important Notes This receiver went offline on August 10th, 2025, due to extensive storm damage. I have not yest decided if I will re-create it at all, or bring it back in a different form. I am leaving this information here because this receiver setup was very low noise, and quite performant over the years it was in operation. VLF E-Field Receiver This page is a summary of my current E-field receiving system, and is constantly being updated as I try different experiments to improve the system.

7-Segment Hexadecimal Display Driver If you build your own microcomputers, or repair older ones (see bus display below), you have probably run into the need to display hexidecimal values on a 7-segment LED display. An internet search will quickly turn up a few options: the MC14495, EP/EEP-ROMS, GALs, and discrete logic. Each of these solutions have advantages and disadvantages: The MC14495 uses a lot of current (up 10 100ma per display), and they cost over $10 each EPROMS/ROMS work just fine, but tend to have larger DIP packages, and require external components (current limiting resistors).

PS/2 Keyboard to Parallel Adapter Older machines and single-board computers, particularly ones from the mid-to-late ’70s through the very early ’80s often used a parallel keyboard input. It was very common during this time for a hobbyist to ‘roll their own’ system with parts from different sources. Keyboards with a 7 or 8 bit parallel ASCII output were available from several sources, but are no longer manufactured. Occasionally you will see one on eBay, but usually for an exorbitant price.

Motivation I enjoy collecting older computers, particularly ones from the mid-to-late 1970s through the early 1980s that run CP/M. Machines from this period commonly have 8" or 5.25" floppy drives. Finding working 8" or 5.25" floppy drives is becoming increasingly difficult. So is finding media. To address this problem for his Atari ST, Jean-Fancois Del Niro created HxC2001, which is a hardware-based floppy drive emulator. Over time support for different drive types and floppy image formats has been added.

Binterm - An Ultra-Simple Terminal Program I work on a wide variety of microcontroller-based systems. My preferred development platforms for cross-compiling are Linux and Mac OS X. Frequently, I need interact with the serial port on the microcontroller system for development and testing purposes. Both Linux and Mac OS support the ‘screen’ command natively. You can use the screen command to connect serial devices like this: screen /dev/serial.device 9600 (or whatever baud rate is necessary) That works just fine, as long as you dont need to dump the output from your microcontroller (uC) system in hex, log it to a file, or any number of other functions.

Motivation Recently, I began a project to build a (reasonably) accurate 3-axis magnetometer. One of the challenges in building a magnetometer is calibrating it with a known magnetic field. Creating a known magnetic field requires using a calibration coil with a known current flowing through it. If you want to make multiple (and consistent) measurements, it is very convenient to have the current under computer control…and that is where the Programmable Current Sink (PCS) got its’ start.

The ionosphere and geophysics have always been “hobbies” of mine. Recently, I began a project to build a 3-axis magnetometer. The first iteration of this project uses FG-3+ fluxgate sensors available from FG Sensors. These sensors are very similar to the sensors once produced by Speake & Co (long out of business). The FG-3+ sensors output a variable period square wave based on the magnetic field strength and direction. The frequency of this square wave typically ranges between 40kHz to over 120kHz.