December 2024

Raspberry Pi-based Clock Radio

This project combines Bluetooth and Internet connectivity with the power of a Raspberry Pi to produce a modern digital alarm clock/ radio fit for the 21^st Century. It automatically adjusts for the correct time so you need never accidentally sleep in again. A built-in audio amplifier with digital volume control can drive internal or external speakers, and using Bluetooth you can stream your favourite music stations from a smartphone or other device.

Many more features are available including web browser access and versatile alarms (20 in all), auto-dimming display and it’s also a Bluetooth media player. Part One this month describes the circuitry, with constructional details following next month.

The VGA PicoMite

With the low-cost Raspberry Pi Pico board, some standard components and our new firmware, you can build this amazingly capable ‘boot to BASIC’ computer. It offers 16-colour VGA, a PS/2 keyboard and runs programs from an SD card. It uses our popular MMBasic interpreter.

Secure Remote Switch (Part 1)

We present a UHF remote switch that uses a rolling code system for improved security. Applications include garage door, electric gate controls and much more besides. Up to 16 professional keyfob transmitters can be used with each receiver, and it has a range of about 22m (line of sight). The receiver has a 12/ 24V relay output and an ‘on-timer’ option ranging from 250ms to 4.5 hours. This month, circuitry and options are described with construction following in Part Two next month.

Multi-channel Volume Control (Part 2)

This sophisticated multi-channel digital volume control can handle up to 20 independent channels and has a colour touchscreen and IR remote control, with OLED add-on controller as an option. We continue this project with Part Two, which describes the construction and setting up of the circuitry.  Note, surface mount components are used and good soldering skills are needed to construct it successfully.

6GHz Attenuator Review

This digitally-programmable module is available off the shelf, so we decided to review one. It can attenuate signals from 1MHz to 6GHz in 0.25dB steps. It’s controlled with five pushbuttons and has a compact OLED screen. What was the verdict? Check out this special review to find out!

All About Capacitors

The humble capacitor is probably the most widely-misunderstood passive  component. This special feature is a mammoth dissertation describing the principles, construction, production and use of fixed and variable capacitors of all types. If you’re getting into electronics, this is a must-read primer on the fundamentals of capacitance.

ZPB30A1 60W Programmable DC Load review

This ready-made constant-current load module from China promises a 1-30V 60W programmable load and battery capacity tester. Using a separate 12V 500mA supply, the MOSFET power driver is fan-cooled and it can draw 0.1 – 9.99A in 10mA increments. We put one through its paces in this special review article.

Also in this issue:

• The Fox Report – comments on how over-amplication can ruin the sound of live performances.
• Net Work – a look at the life and influence of F.J. Camm, the founding Editor of many ‘Practicals’ magazines in Britain.
• Max’s Cool Beans – in the last in the current series of Arduino Bootcamps, Max describes component-level serial data digital principles.
• Techno Talk – the hitherto-unwritten history of the Gerber file, and many more musings.
• Circuit Surgery – continuing an intensive primer on the principles of digital signal processing (DSP).

Next month

High-performance Microphone preamplifier; Model Railway Points controller; USB to PS/2 Converter and much more besides. Contents may be subject to change.