Projects

Projects

Spectrum Analyser

This DC to 50 MHz spectrum analyser uses a standard oscilloscope for display. Dynamic range is better than 70dB using the received signal strength indicator (RSSI) of an FM demodulator IC.

Telephone Exchange

This miniature, 8-line home telephone exchange (PABX) works with standard telephones and features high-quality, user-friendly progress tones and AC ringing. The exchange is all solid-state: no relays.

Mark 1 FORTH Computer

A microcoded stack computer built from discrete logic.

Mark 2 FORTH Computer

Here's another, this time using bitslice and programmable logic devices.

What is FORTH?

Visual Basic Profiler

Here's a software project. This profiler will help you optimise the performance of middle-tier Visual Basic DLLs running under ASP, Microsoft Transaction Server (MTS) on NT4 and Component Services (COM+) on Windows 2000. You can also profile VB Form executables.

Wireless Thermostat

Over the mains carrier current remote control for central heating. Unusually for me, this project was mounted in a box!

Ethernet Receiver

Capturing 10BASE-T Ethernet packets using PLL clock recovery.
Left: a capture transient on the VCO control line.

Fractional-N frequency synthesizers

15-25 MHz Fractional-N Synthesizer with 1 Hz steps
Fast & accurate behavioral PLL Simulator
Reducing PWM distortion phase noise in fractional-N synthesizers (PDF)
Fractional-N Frequency Synthesizer my first attempt

Magnetic Core Memory

An experiment to observe the sense output whilst flipping the state of a single bit in an early Univac III magnetic core memory plane.

Spread Spectrum Link

Experimental direct sequence spread spectrum (DSSS) voice link.

Avalanche Pulse Generator

500 pico-second rise and fall time with one transistor!

Delta Loop Antenna

A water-resistant back-garden HF receiving loop for general shortwave listening.

Huff & Puff VFO Stabiliser

A "fast" Huff & Puff VFO stabiliser using a CPLD.

A Portable Duplex Radio-Telephone (PDF)
Lewis and Milner; THE WIRELESS ENGINEER; September, 1936.

"A practical system of duplex radio-telephony [...] in which each set is made alternately transmitter and receiver at a supersonic frequency. The interrupted oscillation provides super-regenerative amplification [...] The quench frequency must be selected according to the distance between the sets."