Contents
Vol.38, No.02
February 2025
10 Open-Source Software
There is a vast array of quality open-source software available, much of
which is also free. We detail the different kinds of software available for
various jobs such as video, image & audio editing, productivity, CAD etc.
By Dr David Maddison, VK3DSM
Computer software
24 Mini UPS Module
This mini uninterruptible power supply (UPS) module provides continuous
9-12V DC <at> 10W. It’s suitable for smaller devices like a WiFi router, and it
only requires a single lithium-ion cell connected to its 50 x 20mm PCB.
By Jim Rowe
Using electronic modules
40 Antenna Analysis, Part 1
Learn how antennas work and how to design matching circuits for them.
In this first part, we cover the fundamentals, reactance, Smith charts and
other related topics.
By Roderick Wall, VK3YC
Radio antennas
72 Precision Electronics, Part 4
In this fourth installment in the series, we look at how to extend the
current measurement range of our current-sense circuit. We can do that by
switching between two or more shunt resistors.
By Andrew Levido
Electronic design
32 High-Bandwidth Differential Probe
This high-bandwidth and high-voltage Differential Probe is great to use
with a ‘scope. With a max common-mode and differential-mode voltage of
±400V DC and rechargeable battery, it’s perfect for your test bench.
By Andrew Levido
Test equipment project
58 The PicoMite 2
The newest MMBasic interpreter for the Raspberry Pi Pico 2 and “W” variant
is a comprehensive programming environment. It’s not only faster with more
memory, it also has built-in support for HDMI video, USB keyboards, mice etc.
By Geoff Graham & Peter Mather
Raspberry Pi Pico project
64 IR Remote Control Keyfob
This infrared (IR) remote control is one of the smallest we’ve made yet. It
has three buttons that can be programmed wirelessly via NFC (near-field
communications) and it works with many of our other projects.
By Tim Blythman
Remote control project
80 Programmable Frequency Divider
This Divider/Counter reduces the frequency of an incoming signal by
a factor of 3 to 21,327,000 and can be configured via USB. The input
frequency can be 300Hz to 77MHz and is powered from 5-12V DC <at> 20mA.
By Nicholas Vinen
Test equipment project
Project
Page 32
High-Bandwidth
Differential Probe
Antenna Analysis
and Optimisation
Part 1: Page 40
PicoMite 2
Page 58
for the Raspberry Pi Pico 2
2
Editorial Viewpoint
5
Mailbag
31
Subscriptions
46
Circuit Notebook
48
Mini Projects
71
Silicon Chip Kits
88
Serviceman’s Log
94
Online Shop
95
Vintage Radio
100
Silicon Chip Kits
101
Ask Silicon Chip
103
Market Centre
104
Advertising Index
104
Notes & Errata
1. IR repeater
1. Power control for vehicle accessories
2. Power supply transformer tap switching
1. Wireless flashing LEDs
2. Transistor tester
TRF-One AM radio by Dr Hugo Holden
