Practical
Electronics
Volume 54. No. 11
November 2025
ISSN 2632 573X
Contents
Projects and Circuits
Capacitor Discharger by Andrew Levido
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Here is an often-requested project: an easy and safe way to discharge capacitors,
large and small, including those used to store rectified mains (up to about 400V
DC). It’s inexpensive, easy to build and simple to use.
5MHz, 40A Current Probe by Andrew Levido
18
A current probe with a decent bandwidth is a must-have for circuit design and
troubleshooting, especially if you own an oscilloscope. This one adds minimal
series resistance and has plenty of bandwidth for undistorted current waveforms.
3D Printer Filament Dryer, part two by Phil Prosser
34
This design uses simple hardware to keep 3D printer plastic filament warm, driving
moisture out and keeping it out. That’s important for consistent printing results,
especially with PLA or Nylon filament. This month we cover building and testing it.
Series, Features and Columns
Teach-In 12.1: the World of Wireless by Mike Tooley
8
The first instalment in our new 2026 series of Teach-In, “Introduction to Radio and
Wireless Technology”, covers radio frequencies, radio wave propagation, the history of radio communications and a Hands-On modern ‘crystal set’ radio to build.
Max’s Cool Beans by Max The Magnificent
26
Weird & Wonderful Arduino Projects: building a ‘retro’ gaming console. This part, #11,
concentrates on driving 7-segment displays using shift registers.
Techno Talk by Max The Magnificent
42
Bone-conduction headphones, RealSense depth cameras & Eyesynth NIIRA headsets.
Circuit Surgery by Ian Bell
44
Measuring the frequency response of a circuit using a PC sound card, part two.
This month we’re using Room EQ Wizard (REW) to meaures frequency responses.
Net Work by Alan Winstanley
52
Net Work is back again, this time covering Britain’s troubled energy market, eBay’s
attempt to re-invent itself, plus handy test meters and low-cost gadgets from China.
The Life of Nikola Tesla, part two by Dr. David Maddison
58
Nikola Tesla was a prolific inventor, engineer, futurist and essayist. He spoke eight
languages and had a wide range of interests. Despite his ‘mad scientist’ vibe, his
contributions to our modern industrial civilisation are significant.
Audio Out by Jake Rothman
68
The “Transmium” fuzz box is based on germanium transistors. It’s ideal for adding
character to electric guitars and basses, but it could be used with other instruments.
Regulars and Services
Made in Australia & the UK.
Written in Britain, Australia,
the USA and Ireland.
Editorial
Many SSDs have a limited lifespan no matter what
Reader services – Editorial and Advertising Departments
Practical Electronics Back Issue DOWNLOADS – 2024 now available!
Subscribe to Practical Electronics and save money
Practical Electronics PCB Service
PCBs for Practical Electronics projects
Classified ads and Advertiser index
Next month! – highlights of our next issue of Practical Electronics
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Read everywhere.
© Silicon Chip Publications Pty Ltd 2025
Copyright in all drawings, photographs, articles, technical
designs, software and intellectual property published in
Practical Electronics is fully protected, and reproduction
or imitation in whole or in part are expressly forbidden.
The December 2025 issue of Practical Electronics will be
published on Wednesday, 5th of November, 2025 (see p80).
Practical Electronics | November | 2025
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