JUNE 2023

Arduino Programmable DC Load

This programmable load is ideal for testing power supplies, driver circuits and current sources. It handles up to 70W continuous at up to 15V and 4.7A. The project uses an Arduino shield that is easy to understand, build and operate. It can be controlled manually or automated to suit your application. Some limitations of the circuit are outlined in the article.

500W Power Amplifier (Part 3)

This part describes the power supply configuration (with 800VA toroidal transformer)  and the complete assembly details. Copious clear illustrations and photographs will enable constructors to complete this sophisticated amplifier with confidence.

Images shown with insulating perspex cover removed from the capacitor bank.

The ±80V (160V) DC supply across the filter capacitor bank is potentially lethal. Take steps to insulate it using eg Perspex sheet. The capacitor banks also retains charge after powering down and takes time to discharge.

High-Power Buck-Boost LED Driver

This constant-current adjustable regulator is specially designed to drive low-cost 12V LED panels that are now available from China. It outputs 7-34V DC at up to 8A and provides the optimal conditions to drive typical small LED arrays.

Uses surface-mount components throughout. Good soldering skills are required to complete this project successfully.

CJMCU-7620 Gesture Recognition Module

An investigation into the practicalities of this specialist module that can easily be hooked to an Arduino or Micromite. Now you can experiment with the detection and sensing of basic hand gestures, sweeping from any direction as well as clockwise and anti-clockwise motion.

Audio Out

This month our analogue audio expert examines the mechanics of potentiometers in detail, showing common failure modes and workarounds.

Review – EEVBlog 121GW

This features offers a real-world review of this crowdsourced true RMS DMM that incorporates data logging and Bluetooth amongst its features.

Also in this issue:

• Techno Talk – Max muses on technology that comes in different shapes and sizes
• Net Work – how modern online transacting creates all manner of problems for those without Internet access; the spread of ‘dark patterns’ that try to manipulate our behaviour; dropping in on live auctions, and a critical warning for eBay sellers.
• Max’s Cool Beans – Arduino Boot Camp (Part 6) – more coding techniques and basics explained.
• Circuit Surgery – op.amp comparator circuits
• Make it with Micromite – utilising a Philips Hue hub as part of a smart light controller

Next month

Spectral Sound MIDI Synthesiser; MOS Air Quality Sensors; Multimeter Checker & Calibrator.