October 2022

SMD Test Tweezers

This clever device can measure the values of SMD  resistors and capacitors, and it will show diode and LED polarities as well as measuring their forward voltages. The self-contained test probe is powered by an onboard coin cell and it has a high-contrast OLED screen to display the readings. Auto power on/off, the OLED display shows the coin cell battery voltage when no component is connected. PIC micro powered with source code available for download.

Tele-com Telephone Intercom

This is a retro-style intercom system that’s designed to re-purpose traditional telephones that have a bell ringer. It allows two such telephones to be connected to form a ‘private line’ and it has all the features needed to utilise them whether in the UK, USA or Australia/ NZ. Selectable international bell ringing cadence. It can be run ‘off grid’ using two 12V batteries. The circuit uses discrete through-hole components throughout and is straightforward to build.

Touchscreen and Remote Digital Preamp with Tone Controls (Part 2)

This preamp offers audiophiles the best of both worlds, combining the benefits of digital control with the low noise and distortion of an analogue design. A classic Baxandall-type volume and tone control circuit based around op.amps is used in conjunction with high-quality digital potentiometers that provide the adjustments. The fully-featured project has a Micromite colour touchscreen and remote control and offers better than CD sound quality. Part One last month described the circuitry and constructional details, setup and operation are provided in Part Two this month.

Using cheap Asian electronic modules:
Self-contained 3.8GHz Digital Attenuator

We try an off-the-shelf digitally programmable RF attenuator module that can be utilised with RF signals ranging from 1MHz to 3.8GHz by  0-31dB in 1dB steps. Built-in microcontroller and OLED display.

Make it with Micromite: A simple PicoMite GPS tracker

Our super series based around the marvellous Micromite BASIC programmable module continues with a GPS tracker utilising the PicoMite. Configuration and programming details are included.

Net Work

Our long-established column covering Internet, networking and general technological trends investigates a whole-home mesh WiFi system at a price that sounds too good to be true. And there’s exciting news about Britain’s expanding space launch program. Don’t forget to check the Net Work online blog every month, with clickable links already made for you.

Electronic Building Blocks
Selecting and using actuators

More electronics fundamentals are explained, this month we show how to use servos and linear and rotary actuators in control circuitry.

Also in this issue:

• Techno Talk – shining some light on the risk from solar flares
• The Fox Report – Barry Fox exposes Ofcom’s farcical complaints system
• Net Work – a whole-home mesh WiFi system for £20! And more space news.
• Circuit Surgery – continuing an intensive primer on digitally-controlled resistance
• Max’s Cool Beans – Lixie displays and more miscellaneous musings
• Audio Out – Transformers in audio (Part 3)
• KickStart – getting to grips with low-power op.amps (Part 10)
• Electronic Building Blocks – How to use servos and linear and rotary actuators

Next month

USB Cable Tester; Model Railway Carriage Lights; Pocket Weather Station;  Self-contained 6GHz Digital Attenuator. Contents subject to last minute change.