May 2021

7-Band Mono or Stereo Preamplifier

This 7-band equaliser design lets you tailor the sound of an audio channel to suit personal preferences. They can also help correct for room acoustics or deviations in loudspeaker response. The equaliser is presented as a bare board project that can be fitted to existing audio equipment or housed in a cabinet of your own. It features extremely low noise and distortion so they won’t degrade the audio, and they use rotary pots to save space and keep the cost down. Both mono and stereo versions are described – just add your own power supply. Classic through-hole PCB using discrete components means no surface mount experience is needed.

Touchscreen Car Altimeter

This project is a modified version of the Touchscreen Altimeter and Weather Station (PE, December 2018) and has been optimised for in-car use. It utilises ‘QNH’ atmospheric pressure readings for greater and more meaningful accuracy. Uses a Micromite touchscreen LCD BackPack as before.

DIY Solder Reflow Oven with PID Control (Part 2)

With surface-mount printed circuit board construction becoming more commonplace, this project will help hobbyists to make short work of soldering SMD devices onto boards without all the hassle or worries of dealing with these miniature components. This PIC-based temperature controller converts an ordinary domestic 1500W table-top oven into a solder reflow oven. It incorporates proportional/ integral/ differential (PID) control and a thermocouple amplifier to intelligently manage temperature profiles closely for successful reflowing soldering SMDs onto boards, without the risk of temperature ‘overshoot’. It can also hold the oven temperature at anywhere from 20° to 230°C, and can be used for other tasks where temperature control is important, such as curing resins, paint, glue etc.

This month, assembly and finishing off are described along with guidance for reflowing an SMD board.

  Uses surface mount chips and good soldering skills are needed for successful assembly

Make it with Micromite (Part 28):
Internet connection with an ESP32 Wi-Fi module / Part1

Over the next two months our Micromite tutor Phil Boyce will show you how to connect your Micromite Keyring Computer (MKC) to the Internet: not so much for browsing or surfing the net, but more for fetching data such as a time signal or maybe weather or astronomy information from a suitable server.  A worked example using AT commands in a terminal is included. An interesting and useful application for your MKC!

PIC n’ MIX Part 5: PIC18F Development Board

PE’s PIC expert Mike Hibbett continues his PIC development project with some final PCB design tweaks and revisions before summarising the software and hardware tools (mostly for Windows PCs) needed to build a complete PIC 18F programming and development environment.

Also in this issue:

• Techno Talk – magnetic tape hasn’t gone out of fashion, and how to check ‘dirty electricity’
• Net Work – Reolink PTZ cameras, and more space news
• Max’s Cool Beans – simulating John Conway’s Game of Life on Max’s LED array
• Audio Out – building top-quality modules for studio work, starting with a microphone preamplifier for an analogue Vocoder.
• Practically Speaking – Part 3 of this mini series by Jake Rothman on restoring old equipment continues. Many practical hints and tips are provided as Jake continues to refurbish a Leak Stereo 30 amplifier.
• Circuit Surgery – Ian Bell delves into the theory and algebra for solving a circuit: iteration load lines and simulation.

In next month’s issue:

Touchscreen Wide-range RCL Box (Part 1); Roadies’ Test Signal Generator; Low-cost, high precision Thermometer Calibrator; KickStart Part 3 – inductive components.