Silicon ChipContents - September 2025 SILICON CHIP
  1. Contents
  2. Publisher's Letter: Why I don’t put a space between numbers and units
  3. Feature: The Fox Report by Barry Fox
  4. Project: Compact Hi-Fi Headphone Amplifier, part one by Nicholas Vinen
  5. Feature: 0.91-inch monochrome OLED display modules by Jim Rowe
  6. Project: Two Discrete Ideal Bridge Rectifiers by Phil Prosser & Ian Ashford
  7. Feature: Max’s Cool Beans by Max the Magnificent
  8. Project: Automatic LQ Meter by Charles Kosina
  9. Back Issues
  10. Feature: Net Work by Alan Winstanley
  11. Feature: Circuit Surgery by Ian Bell
  12. Feature: Altium Designer 2025 review by Tim Blythman
  13. Project: Dual-Rail Load Protector by Stefan Keller -Tuberg
  14. Back Issues
  15. Feature: Audio Out by Jake Rothman
  16. PartShop
  17. Market Centre
  18. Advertising Index
  19. Back Issues

This is only a preview of the September 2025 issue of Practical Electronics.

You can view 0 of the 80 pages in the full issue.

Articles in this series:
  • The Fox Report (July 2024)
  • The Fox Report (July 2024)
  • The Fox Report (September 2024)
  • The Fox Report (September 2024)
  • The Fox Report (October 2024)
  • The Fox Report (October 2024)
  • The Fox Report (November 2024)
  • The Fox Report (November 2024)
  • The Fox Report (December 2024)
  • The Fox Report (December 2024)
  • The Fox Report (January 2025)
  • The Fox Report (January 2025)
  • The Fox Report (February 2025)
  • The Fox Report (February 2025)
  • The Fox Report (March 2025)
  • The Fox Report (March 2025)
  • The Fox Report (April 2025)
  • The Fox Report (April 2025)
  • The Fox Report (May 2025)
  • The Fox Report (May 2025)
  • The Fox Report (July 2025)
  • The Fox Report (July 2025)
  • The Fox Report (August 2025)
  • The Fox Report (August 2025)
  • The Fox Report (September 2025)
  • The Fox Report (September 2025)
Items relevant to "Compact Hi-Fi Headphone Amplifier, part one":
  • Compact HiFi Headphone Amplifier PCB [01103241] (AUD $7.50)
  • Dual Horizontal PCB-mounting RCA sockets (white/red) [RCA-210] (Component, AUD $2.50)
  • Compact HiFi Headphone Amplifier kit (Component, AUD $70.00)
  • Compact HiFi Headphone Amplifier PCB pattern (PDF download) [01103241] (Free)
  • Compact HiFi Headphone Amplifier panel drilling diagram (Panel Artwork, Free)
Articles in this series:
  • Compact HiFi Headphone Amp (December 2024)
  • Compact HiFi Headphone Amp (December 2024)
  • Compact HiFi Headphone Amp (January 2025)
  • Compact HiFi Headphone Amp (January 2025)
  • Compact Hi-Fi Headphone Amplifier, part one (September 2025)
  • Compact Hi-Fi Headphone Amplifier, part one (September 2025)
Articles in this series:
  • El Cheapo Modules From Asia - Part 1 (October 2016)
  • El Cheapo Modules From Asia - Part 1 (October 2016)
  • El Cheapo Modules From Asia - Part 2 (December 2016)
  • El Cheapo Modules From Asia - Part 2 (December 2016)
  • El Cheapo Modules From Asia - Part 3 (January 2017)
  • El Cheapo Modules From Asia - Part 3 (January 2017)
  • El Cheapo Modules from Asia - Part 4 (February 2017)
  • El Cheapo Modules from Asia - Part 4 (February 2017)
  • El Cheapo Modules, Part 5: LCD module with I²C (March 2017)
  • El Cheapo Modules, Part 5: LCD module with I²C (March 2017)
  • El Cheapo Modules, Part 6: Direct Digital Synthesiser (April 2017)
  • El Cheapo Modules, Part 6: Direct Digital Synthesiser (April 2017)
  • El Cheapo Modules, Part 7: LED Matrix displays (June 2017)
  • El Cheapo Modules, Part 7: LED Matrix displays (June 2017)
  • El Cheapo Modules: Li-ion & LiPo Chargers (August 2017)
  • El Cheapo Modules: Li-ion & LiPo Chargers (August 2017)
  • El Cheapo modules Part 9: AD9850 DDS module (September 2017)
  • El Cheapo modules Part 9: AD9850 DDS module (September 2017)
  • El Cheapo Modules Part 10: GPS receivers (October 2017)
  • El Cheapo Modules Part 10: GPS receivers (October 2017)
  • El Cheapo Modules 11: Pressure/Temperature Sensors (December 2017)
  • El Cheapo Modules 11: Pressure/Temperature Sensors (December 2017)
  • El Cheapo Modules 12: 2.4GHz Wireless Data Modules (January 2018)
  • El Cheapo Modules 12: 2.4GHz Wireless Data Modules (January 2018)
  • El Cheapo Modules 13: sensing motion and moisture (February 2018)
  • El Cheapo Modules 13: sensing motion and moisture (February 2018)
  • El Cheapo Modules 14: Logarithmic RF Detector (March 2018)
  • El Cheapo Modules 14: Logarithmic RF Detector (March 2018)
  • El Cheapo Modules 16: 35-4400MHz frequency generator (May 2018)
  • El Cheapo Modules 16: 35-4400MHz frequency generator (May 2018)
  • El Cheapo Modules 17: 4GHz digital attenuator (June 2018)
  • El Cheapo Modules 17: 4GHz digital attenuator (June 2018)
  • El Cheapo: 500MHz frequency counter and preamp (July 2018)
  • El Cheapo: 500MHz frequency counter and preamp (July 2018)
  • El Cheapo modules Part 19 – Arduino NFC Shield (September 2018)
  • El Cheapo modules Part 19 – Arduino NFC Shield (September 2018)
  • El cheapo modules, part 20: two tiny compass modules (November 2018)
  • El cheapo modules, part 20: two tiny compass modules (November 2018)
  • El cheapo modules, part 21: stamp-sized audio player (December 2018)
  • El cheapo modules, part 21: stamp-sized audio player (December 2018)
  • El Cheapo Modules 22: Stepper Motor Drivers (February 2019)
  • El Cheapo Modules 22: Stepper Motor Drivers (February 2019)
  • El Cheapo Modules 23: Galvanic Skin Response (March 2019)
  • El Cheapo Modules 23: Galvanic Skin Response (March 2019)
  • El Cheapo Modules: Class D amplifier modules (May 2019)
  • El Cheapo Modules: Class D amplifier modules (May 2019)
  • El Cheapo Modules: Long Range (LoRa) Transceivers (June 2019)
  • El Cheapo Modules: Long Range (LoRa) Transceivers (June 2019)
  • El Cheapo Modules: AD584 Precision Voltage References (July 2019)
  • El Cheapo Modules: AD584 Precision Voltage References (July 2019)
  • Three I-O Expanders to give you more control! (November 2019)
  • Three I-O Expanders to give you more control! (November 2019)
  • El Cheapo modules: “Intelligent” 8x8 RGB LED Matrix (January 2020)
  • El Cheapo modules: “Intelligent” 8x8 RGB LED Matrix (January 2020)
  • El Cheapo modules: 8-channel USB Logic Analyser (February 2020)
  • El Cheapo modules: 8-channel USB Logic Analyser (February 2020)
  • New w-i-d-e-b-a-n-d RTL-SDR modules (May 2020)
  • New w-i-d-e-b-a-n-d RTL-SDR modules (May 2020)
  • New w-i-d-e-b-a-n-d RTL-SDR modules, Part 2 (June 2020)
  • New w-i-d-e-b-a-n-d RTL-SDR modules, Part 2 (June 2020)
  • El Cheapo Modules: Mini Digital Volt/Amp Panel Meters (December 2020)
  • El Cheapo Modules: Mini Digital Volt/Amp Panel Meters (December 2020)
  • El Cheapo Modules: Mini Digital AC Panel Meters (January 2021)
  • El Cheapo Modules: Mini Digital AC Panel Meters (January 2021)
  • El Cheapo Modules: LCR-T4 Digital Multi-Tester (February 2021)
  • El Cheapo Modules: LCR-T4 Digital Multi-Tester (February 2021)
  • El Cheapo Modules: USB-PD chargers (July 2021)
  • El Cheapo Modules: USB-PD chargers (July 2021)
  • El Cheapo Modules: USB-PD Triggers (August 2021)
  • El Cheapo Modules: USB-PD Triggers (August 2021)
  • El Cheapo Modules: 3.8GHz Digital Attenuator (October 2021)
  • El Cheapo Modules: 3.8GHz Digital Attenuator (October 2021)
  • El Cheapo Modules: 6GHz Digital Attenuator (November 2021)
  • El Cheapo Modules: 6GHz Digital Attenuator (November 2021)
  • El Cheapo Modules: 35MHz-4.4GHz Signal Generator (December 2021)
  • El Cheapo Modules: 35MHz-4.4GHz Signal Generator (December 2021)
  • El Cheapo Modules: LTDZ Spectrum Analyser (January 2022)
  • El Cheapo Modules: LTDZ Spectrum Analyser (January 2022)
  • Low-noise HF-UHF Amplifiers (February 2022)
  • Low-noise HF-UHF Amplifiers (February 2022)
  • A Gesture Recognition Module (March 2022)
  • A Gesture Recognition Module (March 2022)
  • Air Quality Sensors (May 2022)
  • Air Quality Sensors (May 2022)
  • MOS Air Quality Sensors (June 2022)
  • MOS Air Quality Sensors (June 2022)
  • PAS CO2 Air Quality Sensor (July 2022)
  • PAS CO2 Air Quality Sensor (July 2022)
  • Particulate Matter (PM) Sensors (November 2022)
  • Particulate Matter (PM) Sensors (November 2022)
  • Heart Rate Sensor Module (February 2023)
  • Heart Rate Sensor Module (February 2023)
  • UVM-30A UV Light Sensor (May 2023)
  • UVM-30A UV Light Sensor (May 2023)
  • VL6180X Rangefinding Module (July 2023)
  • VL6180X Rangefinding Module (July 2023)
  • pH Meter Module (September 2023)
  • pH Meter Module (September 2023)
  • 1.3in Monochrome OLED Display (October 2023)
  • 1.3in Monochrome OLED Display (October 2023)
  • 16-bit precision 4-input ADC (November 2023)
  • 16-bit precision 4-input ADC (November 2023)
  • 1-24V USB Power Supply (October 2024)
  • 1-24V USB Power Supply (October 2024)
  • 14-segment, 4-digit LED Display Modules (November 2024)
  • 0.91-inch OLED Screen (November 2024)
  • 14-segment, 4-digit LED Display Modules (November 2024)
  • 0.91-inch OLED Screen (November 2024)
  • The Quason VL6180X laser rangefinder module (January 2025)
  • The Quason VL6180X laser rangefinder module (January 2025)
  • TCS230 Colour Sensor (January 2025)
  • TCS230 Colour Sensor (January 2025)
  • Using Electronic Modules: 1-24V Adjustable USB Power Supply (February 2025)
  • Using Electronic Modules: 1-24V Adjustable USB Power Supply (February 2025)
  • Low-cost electronic modules: 8×16 LED Matrix module (July 2025)
  • Low-cost electronic modules: 8×16 LED Matrix module (July 2025)
  • Modules: Thin-Film Pressure Sensor (August 2025)
  • Modules: Thin-Film Pressure Sensor (August 2025)
  • 0.91-inch monochrome OLED display modules (September 2025)
  • 0.91-inch monochrome OLED display modules (September 2025)
Articles in this series:
  • Max’s Cool Beans (January 2025)
  • Max’s Cool Beans (January 2025)
  • Max’s Cool Beans (February 2025)
  • Max’s Cool Beans (February 2025)
  • Max’s Cool Beans (March 2025)
  • Max’s Cool Beans (March 2025)
  • Max’s Cool Beans (April 2025)
  • Max’s Cool Beans (April 2025)
  • Max’s Cool Beans (May 2025)
  • Max’s Cool Beans (May 2025)
  • Max’s Cool Beans (June 2025)
  • Max’s Cool Beans (June 2025)
  • Max’s Cool Beans (July 2025)
  • Max’s Cool Beans (July 2025)
  • Max’s Cool Beans (August 2025)
  • Max’s Cool Beans (August 2025)
  • Max’s Cool Beans (September 2025)
  • Max’s Cool Beans (September 2025)
Articles in this series:
  • Win a Microchip Explorer 8 Development Kit (April 2024)
  • Win a Microchip Explorer 8 Development Kit (April 2024)
  • Net Work (May 2024)
  • Net Work (May 2024)
  • Net Work (June 2024)
  • Net Work (June 2024)
  • Net Work (July 2024)
  • Net Work (July 2024)
  • Net Work (August 2024)
  • Net Work (August 2024)
  • Net Work (September 2024)
  • Net Work (September 2024)
  • Net Work (October 2024)
  • Net Work (October 2024)
  • Net Work (November 2024)
  • Net Work (November 2024)
  • Net Work (December 2024)
  • Net Work (December 2024)
  • Net Work (January 2025)
  • Net Work (January 2025)
  • Net Work (February 2025)
  • Net Work (February 2025)
  • Net Work (March 2025)
  • Net Work (March 2025)
  • Net Work (April 2025)
  • Net Work (April 2025)
  • Net Work (September 2025)
  • Net Work (September 2025)
Articles in this series:
  • Circuit Surgery (April 2024)
  • STEWART OF READING (April 2024)
  • Circuit Surgery (April 2024)
  • STEWART OF READING (April 2024)
  • Circuit Surgery (May 2024)
  • Circuit Surgery (May 2024)
  • Circuit Surgery (June 2024)
  • Circuit Surgery (June 2024)
  • Circuit Surgery (July 2024)
  • Circuit Surgery (July 2024)
  • Circuit Surgery (August 2024)
  • Circuit Surgery (August 2024)
  • Circuit Surgery (September 2024)
  • Circuit Surgery (September 2024)
  • Circuit Surgery (October 2024)
  • Circuit Surgery (October 2024)
  • Circuit Surgery (November 2024)
  • Circuit Surgery (November 2024)
  • Circuit Surgery (December 2024)
  • Circuit Surgery (December 2024)
  • Circuit Surgery (January 2025)
  • Circuit Surgery (January 2025)
  • Circuit Surgery (February 2025)
  • Circuit Surgery (February 2025)
  • Circuit Surgery (March 2025)
  • Circuit Surgery (March 2025)
  • Circuit Surgery (April 2025)
  • Circuit Surgery (April 2025)
  • Circuit Surgery (May 2025)
  • Circuit Surgery (May 2025)
  • Circuit Surgery (June 2025)
  • Circuit Surgery (June 2025)
  • Circuit Surgery (July 2025)
  • Circuit Surgery (July 2025)
  • Circuit Surgery (August 2025)
  • Circuit Surgery (August 2025)
  • Circuit Surgery (September 2025)
  • Circuit Surgery (September 2025)
Articles in this series:
  • Audio Out (January 2024)
  • Audio Out (January 2024)
  • Audio Out (February 2024)
  • Audio Out (February 2024)
  • AUDIO OUT (April 2024)
  • AUDIO OUT (April 2024)
  • Audio Out (May 2024)
  • Audio Out (May 2024)
  • Audio Out (June 2024)
  • Audio Out (June 2024)
  • Audio Out (July 2024)
  • Audio Out (July 2024)
  • Audio Out (August 2024)
  • Audio Out (August 2024)
  • Audio Out (September 2024)
  • Audio Out (September 2024)
  • Audio Out (October 2024)
  • Audio Out (October 2024)
  • Audio Out (March 2025)
  • Audio Out (March 2025)
  • Audio Out (April 2025)
  • Audio Out (April 2025)
  • Audio Out (May 2025)
  • Audio Out (May 2025)
  • Audio Out (June 2025)
  • Audio Out (June 2025)
  • Audio Out (July 2025)
  • Audio Out (July 2025)
  • Audio Out (August 2025)
  • Audio Out (August 2025)
  • Audio Out (September 2025)
  • Audio Out (September 2025)
Practical Electronics Volume 54. No. 9 September 2025 ISSN 2632 573X Contents Projects and Circuits Compact Hi-Fi Headphone Amplifier, part one by Nicholas Vinen 4 This Headphone Amplifier is easy to build, sounds great, is inexpensive and fits into a compact case. It’s ideal for beginners or those who want to get the best out of a set of traditional wired headphones. It’s plugpack-powered, so no mains wiring is required. Two Discrete Ideal Bridge Rectifiers by Phil Prosser & Ian Ashford 18 This simple circuit uses just a handful of transistors, diodes and resistors. But it still provides a very useful function: active rectification of the output of a centre-tapped transformer or combining two DC supplies with low losses. Automatic LQ Meter by Charles Kosina 34 A Q Meter is an indispensable tool for anyone contemplating RF design. This new design features two instruments in one, measuring inductance from 0.1 to 999μH and Q from 10 to 300 with a test frequency from 100kHz to 90MHz! Dual-Rail Load Protector by Stefan Keller-Tuberg 60 It disconnects a load from its power supply if the voltage is reversed or too high. It also disconnects the load if it draws current above the adjustable trip level. Its dual-rail support means it can work with devices like audio amplifiers with a split supply. Series, Features and Columns The Fox Report by Barry Fox A reasonably priced solution for high-quality analog audio to digital conversion. 3 0.91-inch monochrome OLED display modules by Jim Rowe 12 Small monochrome OLED display modules have become widely available at a low cost in the last few years. This one measures just 37.5 × 11.5 × 4.5mm but has a useful 128 × 32 pixel display that’s either white or blue. Techno Talk by Max The Magnificent 16 We take breadboards for granted, but the modern version evolved over several decades. Max’s Cool Beans by Max The Magnificent Weird & Wonderful Arduino Projects, part 9: a crash course in digital logic. 26 Net Work by Alan Winstanley 44 The return of my occasional column brings news of trends in smart meters, the onslaught of Chinese-made electric vehicles, and tempts readers into trying Temu. Circuit Surgery by Ian Bell 48 Topics in digital signal processing – Implementing DSP on a microcontroller, part 4. It is finally time to implement an FIR low-pass filter on our microcontroller board. Altium Designer 2025 review by Tim Blythman 56 We look at the features and improvements added to this EDA software in its last update. Audio Out by Jake Rothman 70 You can now easily build my cascode amplifier using this custom-designed PCB. Regulars and Services Made in Australia & the UK. Written in Britain, Australia, the USA and Ireland. 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 October 2025 issue of Practical Electronics will be published on Tuesday, 4th of September 2025 (see p80). Practical Electronics | September | 2025 Editorial Values and units shouldn’t be separated Reader services – Editorial and Advertising Departments Subscribe to Practical Electronics and save money Practical Electronics Back Issue DOWNLOADS – 2024 now available! Practical Electronics PCB Service PCBs for Practical Electronics projects Classified ads and Advertiser index Next month! – highlights of our next issue of Practical Electronics 2 2 43 69 76 79 80 Renewals paid by PayPal, Visa and Mastercard are now handled via our website: www.electronpublishing.com 1