September 2016

Compact Hybrid SwitchMode 100W Bench Supply (Pt 1)

This very compact bench PSU offers 0-40V up to 5A with fast and accurate current limiting. It has a 3½ digit 7-segment LED readout of current and voltage. It can be powered from any 12-24V DC supply such as a PC or laptop power supply or lead acid battery. A combination of switchmode and linear circuitry offers the added benefits of good regulation and low residual noise.

The switchmode circuitry is described this month, with more circuit and construction details in the October 2016 issue.

Speedo Corrector (Mk. 3)

If you’ve swapped your car’s instrument panel, gearbox or differential  with one from a different vehicle, then your speedo and odometer may no longer be correct. The same is true if you have fitted wheels or tyres with a different overall diameter. This Speedo Corrector project for electronic speedometers and tachometers is microcontroller based and it takes the digital speedo/ tacho signal and multiplies it up or down according to a trimpot setting, allowing you to correct the reading.

12 or 24V operation, built-in adjustment to compensate for speedo lag. PIC16F88 based, with source code downloadable from our Library.

  Note the warnings in the article about disassembling the steering wheel section which may affect your airbag.

Using this project on your car may be classed as a modification that affects your vehicle insurance.

LED Party Strobe (Mk. II)

A brilliantly simple design based upon a 230V 30W LED floodlight which can be sourced cheaply online.

It uses a MOSFET driver to flash a cheap LED floodlight at up to approx 18 Hz or so (variable). This article describes full construction along with some interesting info on LED arrays.

Introducing the Arduino
Part 8 : IR remote control

Our Arduino experts continue with their infra-red control theme by investigating means of adding IR remote control to Arduino Uno and Nano projects. IR transmitters and receivers are explored and we get to grips with the IR code library. Lastly, a multi-channel IR remote control system is described that allows you to control heating, lighting and a host of other gadgets from your armchair.

Also in this issue:

• Techno Talk – the science behind LoRa, and utility meter radio communications and eco-powering them
• Net Work – second part of a special feature charting the evolution of the Internet over the past 50 years
• Circuit Surgery – our in-house surgeon tackles the thorny aspects of a.c. bias and MLCCs (multilayer ceramic capacitors).
• PIC n MIX – continuing with our beginner’s guide to PIC microcontrollers, looking into more code basics and some simple applications for novice programmers. Everything you need to get started in PIC microcontrollers is here, so don’t miss out on this great tutorial series!
• Audio Out – our hands-on audiophile offers a retro amp-speaker combo (Part 3)
• Max’s Hot Beans – Max builds a super-PC for VR gaming with the Oculus Rift

In next month’s issue:

Arduino-based USB electrocardiogram with datalogger; Compact Hybrid SwitchMode 100W Bench Supply (Part 2), 5-Element Yagi Antenna; Teach-In 2016 (Part 9): connecting Arduino to a LAN and the Internet.