This page has a link to the projects I am have constructed. Some of the pages are still under construction and only the relevant schematic without description and test results is shown.

The projects described are free to use, modify and or distribute. However the original author must be referenced. The author is indemnified from any responsibility when using these projects.  Use them at your own risk

Motobox – Motobox is a generic motor controller for Stepper, DC and Servo Motors. It can be addressed very easily by sending ASCII based commands from the terminal. The module is able to monitor itself and has overcurrent protection. It can drive up to 2A per channel and has two channels. It was published in Elector Magazine in the July/August issue in 2007.

Active Load – This project is used to test power supplies up to 1A. It has a bar graph display output for quick viewing of the load current as well as a BNC connection to an oscilloscope to see how the power supply reacts to load transients

Oscilloscope Impedance Convertor – There are cases when the oscilloscope has only a 50ohm input and one needs to interface a 1Mohm probe with it. This circuit creates an impedance conversion from 1Mohm to 50ohm with the introduction of minimum distortion. It also has output protection as it does not allow the output to go above 1V. For 1 10:1 probe this allows an effective input of 10V peak. The bandwith of the circuits rolls off after 30MHz. A increased bandwidth version is on the way.

Precision DC amplifier – This project is a low bandwidth amplifier (100kHz) which is primary designed to amplify low voltage signals in the region of 1mV. It features offset voltage trimming and low noise regulators

Lock in Amplifier – This is a demonstration project to show the capabilities of a lock in amplifier. It consists of two modules, a 20KHz transmitter with the ability to be modulated 1Hz and a receiver that is tuned to lock at the 20kHz waveform. The receiver is designed with a Phase Locked Loop (PLL) so that no connection is needed between the modules. Another option is to bypass the PLL and use a bandpass filter with a comparator to increase the regenerate the carrier frequency improve the overall range. It is a very good didactic project. This is a Work in progress

Versatile Power Supply – This is a fixed output power supply entirely design using switched mode convertors. The outputs are +12V, +5V, -12V, -5V. Any plugpack d.c. supply that has a voltage greater than 13.4V will do. The maximum output current depends on the maximum load current of the d.c. supply.

Various small projects

Bicycle Alarm

Bicycle Alarm with low power battery flasher

Simple speedometer