May 2012

Compact High-Performance 12V Stereo Amplifier

It might be small but this 12V stereo amplifier packs quite a punch for its size – 20W per channel into 4 ohms with low distortion at lower outputs of typically 0.03%. It will easily run from a small, portable SLA (sealed lead acid) battery, and it uses just two IC’s. Phono input, 500mV r.m.s. into 8.3k. The 12V amplifier is straightforward to assemble if you have some soldering experience. It comes to you in a fully-detailed colour 12 page article so you can assemble the project with confidence. Just the thing for mobile events, street performances, 12V alarms systems and more.

Low-Power Car/ Bike USB Charger

This 12V USB charger will recharge many 5V USB devices from a car or motorcycle supply. It benefits from a remarkably low quiescent current (160µA) that enables it to be permanently connected to a 12V battery, provided the USB device is unplugged to prevent drainage. Output current 525mA maximum. 12V 300mA input. Details of charging Apple devices also included.

High Quality Digital Audio Signal Generator (Part 3)

This sophisticated digital test gear has a backlit LCD display and TOSLINK and coax S/PDIF digital outputs with two analogue audio outputs as well. Generates sine, square, triangle and two sawtooth waveforms, 1Hz to 24kHz.  THD 0.06% (internal DAC) or 0.0006% (ext DAC). Switch between S/PDIF 20-bit and AES/EBU 24-bit modes. PICmicro PIC33FJ based. In Part 3 this month, the operation of this sophisticated project is described.

Solar-Power Lighting Controller (Part 1)

Need lighting when there’s no power source? A self-contained sun-powered sealed lead acid (SLA) charger and high-efficiency lighting are the answer. This self-contained solar control unit boasts high efficiency, three stage charging and Maximum Power Point Tracking. It uses a 5W solar panel with 3-stage charging and is ideal for l.e.d. lighting powered by a 12V SLA battery. Can be controlled by a PIR, switched or by ambient light turn-on. Lamp timer included. Details of a 3-LED lamp are also described. PIC 16F88 powered, free source code available from our Library. Many applications including security or pathway lighting, sheds and more. Next month, constructional details are provided along with suggestions for an LED light.

Jump Start (Part 1)

A brand new series aimed at the beginner in electronics. All the way through to 2013 we’ll offer simple “seasonal” projects that electronics novices can build with confidence. Each circuit uses the popular and powerful ‘Circuit Wizard’ software package as a design, simulation and printed circuit board layout tool to help explore their operation and customise them on-screen. (See our previous Teach-In series for an introduction to Circuit Wizard.)

Our simple circuits are described step by step and include a printed circuit board that can be purchased from our PCB Service as normal, or you can etch your own from the artwork provided. You can also customise the PCB in Circuit Wizard.

Jump Start is the modern way of introducing electronic principles and the project this month is based around a moisture detector circuit. It can be adapted using the techniques described to become a rain alarm or plant-pot moisture monitor. If you’re new to electronics and want to learn and explore all the basics, then Jump Start is for you! Jump in!

Also in this issue:

• • Techno Talk on the latest trends in electronics, mobile and radio technology
  • Circuit Surgery answers more readers’ queries and explores the intricacies of driving triacs
  • Practically Speaking – hands-on workshop advice for hobbyists points the way on panel labelling
  • PIC n MIX – an altitude indicator using chipKIT Arduino, PS and a Nokia phone LCD.
  • Net Work – investigating GeoIP, which claims to pinpoint your location from your IP address, and a summary of current online frauds to watch out for.