March 2017

Speech Timer for Contests and Debates

The perfect companion for conferences and speeches, debating societies, Toastmaster  contests and more, our Speech Timer has a 3-digit numerical timer display (58mm high digits) and a manual ending buzzer to help ensure speakers don’t overrun their time slot in an event’s running order.

Observing the rules of the Toastmaster 2015/16 Speech Contest Rule Book, this design incorporates many useful features as well as the standard green, amber and red lights of ordinary conference timers, and comes complete with a tiny infrared remote control. Count-up or countdown modes, battery or mains adaptor powered, a PIC micro design with hex file code available from our Library.

Arduino-based Fridge Monitor and Data Logger

This remote-logging design is based on an Arduino and it checks temperature and humidity in your refrigerator (or elsewhere) and logs it to a microSD card. You’ll see how much the temperature and humidity vary as the compressor cycles on and off, how often the door is opened and so on. Dual line LCD display of data. A good project for anyone interested  in learning how to use Arduino boards. It is provided as a circuit only and constructional details are left to the builder.

Solar MPPT Charger & Lighting Controller (Part 2)

This ‘maximum power point tracking’ (MPPT) solar charger/ light controller will work with 12V or 24V solar panels to charge a corresponding lead-acid or Lithium-Ion Phosphate battery. You can then use the battery to run 12V d.c. lighting or a 12V/24V 230V a.c inverter to power lighting or other moderate mains loads including high-efficient LED lighting.

In Part 2 this month, constructional details, hints and tips and setting up are described. Modifications for 24V d.c. operation are also included.

Meet the Mighty Micromite (Part 2)

If ever you wanted to start using microcontrollers but found the programming difficult, then this might be for you! The Micromite is a low-cost 32-bit MCU programmed in a Microsoft-compatible version of the BASIC interpreter, with non-volatile memory, floating point, arrays and extensive string handling to name just a few benefits.

This is a great concept for electronics hobbyists, especially those who’ve programmed in BASIC, and Micromite offers an ultra-low-cost opportunity to harness the power of microcontrollers in many projects. In Part 2 we describe the editor, the board’s I/O pins and interfacing to touch screens.

 Handy Micromite Links:

UK Micromite Shop http://micromite.org/

http://geoffg.net/micromite.html

http://www.thebackshed.com/forum/Microcontrollers

http://tera-term.en.lo4d.com

http://www.c-com.com.au/MMedit.htm

PIC n MIX Binary Clock

Building a PIC-powered LED Binary Clock, helped by lessons learned from earlier articles. Our unique series for PIC microcontroller enthusiasts.

  Please Take Note

On the stripboard layout Fig 4, for correct operation a cut is needed in the track at location M11.

Also in this issue:

• Ingenuity Unlimited – readers’ own circuit ideas
• Net Work – how to log into websites using a fingerprint scanner
• Circuit Surgery – Direct Digital Synthesis and filtering. Our in-house surgeon explains.
• LabNation Smartscope Review – looking at a pint-sized test lab that hooks to a phone or PC
• Max’s Cool Beans – Max dreams of his latest project, an air-wired brain!
• Electronic Building Blocks – more handy tips and ideas using low-cost modules that can be sourced online.
• Interface – analogue signal conditioning techniques

Next month

Microwave Leakage Detector; Arduino Multifunction-24-Bit Measuring Shield (Part 1); Battery Pack Cell Balancer; meet the mighty Micromite (Part3).