A variable gain hybrid-cascode amplifier stage followed by separate feedback amplifier stage, as used for amplifying the output from AD9850 DDS module as the basis for an HF signal generator.

An ESP8266 WIFI module interfaced to a relay allows for a 1000W/240v swimming-pool filter pump to be remote controlled. It turns on and off automatically depending on how much energy is available from the solar system. Software includes NodeMCU general-purpose telnet server, and Perl client utility.

A quick tutoral guide to setting up a Linux development environment for the ESP8266 WIFI enabled microcontroller. Intended for someone who might have just taken delivery of their first module and is wonder where to start. Covers hardware, firmware, C SDK, and NodeMCU Lua.

Suitable for morse code beacons, repeater idents and the like, this library is implemented as a state machine and hence allowing for other processing to be done whilst the morse is being set.

Made by bending a coat hanger, this antenna is for 70cm and can be scaled for UHF CB. It works well, especially considering how quick and easy it is to make.

An interactive map showing Australian amateur radio repeaters. Navigate as required and click on a repeater-site icon to display frequency, ctcss and other details and notes. Display all repeaters or select by band.

The concepts behind direct digital synthesis (DDS) can be explained without the need for complex maths nor heavy-duty digital electronics theory. This tutorial describes how DDS works in simple and easy to understand terms.

A half-wave end-fed for 2m is built from PVC pipe and a couple of meters of RG58 coax. This easily reproducible design from VK2ZOI can be made quickly and performs well. The addition of some tinfoil and sticky tape turns this into a dual-band 70cm collinear.

A self contained programming adapter for PRM80 series radios that is built into a DB9 to RJ45 convertor using a miniature MAX3232 module for level convertion. Power is obtained from the radio via the programming cable.

A DIY build of VK2BTL's sensitive field strength meter circuit design, using parts from an old CB SWR meter. Ideal for testing antenna, radio control and handheld transmitters.