February 2024

Active Mains Soft Starter (Part 1)

High start-up or ‘inrush’ current surges can be disruptive or even dangerous, causing damaging ‘brownout’ voltage dips, blowing light bulbs or electronics, or tripping the circuit breaker when power is first applied. This super-intelligent Active Soft Starter overcomes this, by ramping up current slowly when power is first applied. This can also reduce the unnerving ‘kick’ you get from many power tools such as angle grinders when they switch on. The design has a 10A continuous rating and offers the constructor six startup rates from 500mS to 10S. PIC microcontroller-based, with source code downloadable from our website.

Warning! Mains voltage is present throughout the circuitry.  Extreme care must be taken at all times to avoid accidental electric shock

Advanced SMD Test Tweezers (Part 1)

This astonishing piece of test gear will find a place in any advanced constructor’s toolkit. Our latest Advanced SMD Test Tweezers are a major upgrade of our earlier tweezer designs (October 2022 and May 2023 issues), offering more functionality, higher resolution measurements and a larger, higher resolution OLED display. More importantly, there are new measuring modes including an oscilloscope, voltmeter and an I/V curve plotter. Even a tone/ square wave generator is bundled in as well.

We hope our screenshots whet your appetite! Circuit principles are described in Part One this month, with purchasing, assembly and calibration details following in Part 2 next month.

Active Subwoofer (Part 2)

Fabrication and final assembly details of the Active Subwoofer are shown this month as we install the internal 180W amplifier and complete all the interwiring.

Also in this issue

• Techno Talk – Max ponders trends in chip fabrication and density, and possibly a ‘chiplet-based’ future using multiple silicon chips contained in one device.
• Net Work suggests some interesting and unusual hand and power tools available on import, plus there’s an AI-generated ‘influencer’ and more news from the space programme.
• Max’s Cool Beans – Arduino Bootcamp (Part 14). Max continues with his foray into the world of the Arduino with ideas for using them with ultrasonic sensors.
• Circuit Surgery – continuining an intensive primer on the principles of frequency shifting and superheterodyning receivers.
• MitchElectronics – Part 3 – Introducing the op amp. Basic principles of operational amplifiers are clearly explained along with some practical applications.
• Audio Out – investigating high quality discrete buffer circuits including FET, Darlington and valve (vacuum tube) applications.

Next month

Advanced SMD Test tweezers (Part 2);  Active Mains Soft Starter (part 2); Digital Volume Control Potentiometer. Contents may be subject to change.