January 2025

High-quality Microphone pre-amp

This compact but high quality microphone preamplifier offers a flat frequency response, very low distortion, low noise and adjustable gain. It offers switchable 48V phantom power as well. The inputs and outputs are protected against most forms of abuse and the pre-amp operates from a common 9V power pack.  The circuit is built on a pcb using discrete through-hole components.

USB to PS/2 Keyboard and Mouse Adaptor

Although USB keyboards have been around for some 20 years, numerous devices still use the PS/2 interface. It’s easy to use with a microcontroller, so kit-form computers like the VGA PicoMite includes a PS/2 port. Using this adaptor, you can connect a USB keyboard to a VGA PicoMite or anything else that needs a PS/2 keyboard.

Raspberry Pi-based Clock Radio (part 2)

As we explained in last month’s issue, this new clock radio can also act as a media player, as shown above with an iPad, and it also has a multitude of alarm options. It utilises a Raspberry Pi to show the time on a traditional-style seven-segment LED display. Classic 74HCT discrete logic chips are sure to appeal to constructors young and old. Full constructional details and operating instructions are provided in this month’s article.

Secure Remote Mains Switch (part 2)

This new Secure Remote Switch uses rolling codes for high security. The DC-powered receiver can be mounted almost anywhere, and multiple transmitters can be used. We offer designs for both module-based and discrete component transmitters with a key fob form factor. This month, there’s more theory and full constructional details.

The History of Electronics (part 1)

The technology of microelectronics is advancing at an ever-increasing rate, so we thought that it was high time that we revisited the origins of electronics and the stories of its many inventors, discoveries and inventions. Static electricity is first observed and recorded some 500 years BCE, so that’s where the first part of this informative six-part reference series begins.

Quason VL6180X Laser RangeFinder

This special feature examines applications for the VL6180X laser rangefinder and light level sensor. It uses infra-red light to accurately sense the proximity of objects up to 100mm away. The tiny surface-mount module is also likely to be of interest to anyone involved with robotic devices.

Introduction to Precision Electronics (part 1)

This is the first article in a series that aims to cover the basics of precision electronics design. Topics covered include precision op.amps, instrumentation amplifiers, signal switching and noise, and real-life components are used to demonstrate the concepts in a practical way.

NEW SERIES! Max’s Cool Beans
Weird & Wonderful Arduino projects
Part 1: DIP LED bar graph displays

Max tackles some of the practicalities of using LEDs and bargraph displays, tutorials and exercises designed with Arduino users in mind.

Also in this issue:

• Net Work: the origins of Veroboard. Tracing the history of the development in the 1960s of the single most critical product that enabled hobby electronics to flourish, and is still widely used at the present day. Details of the original patents and early press photos are included.
• The Fox Report: how to avoid being fobbed off or misled by a plague of AI bots.
• Techno Talk: how sophisticated test equipment has become more affordable and is now well within the reach of many hobbyists.
• Circuit Surgery: continuing an intensive primer on digital signal processing and signal filtering in the digital domain.

In the February 2025 issue

Laser communicator, mains power-up sequencer; model railway points controller. Contents may be subject to change.