April 2007 Issue
A summary of this month's contents.
Students' 20W Amplifier
Great sound from this inexpensive and easy to build 20W single channel amplifier module. This low distortion amplifier is based on a single chip LM1875 and for a modest design has a very respectable specification. A separate split power supply board is also described. Our 20W amplifier module offers unbeatable value and simplicity of construction and is the perfect choice for many audio-related projects. As always, we include all assembly and testing details to enable you to construct this project with full confidence.
- S/N of 105dB
- Distortion < 0.04% for 1kHz @ 20W
- Frequency response 14Hz to beyond 100kHz.
- Output short-circuit proof
- Thermal overload protection
Star High Power LED Power Supply
This cleverly designed project allows a Luxeon-type Star high power LED to run safely from a 12V supply. The intelligent way of powering high power Star-type LEDs and the ideal choice for cars, caravans and boat owners, the 'switching' design is far more power efficient than a brute-force linear supply, and means longer battery life. Extra protection included to prevent excessive discharge: avoids the risk of flattening the battery.
- Powers one or two 1 Watt or 3 Watt Stars, or a single 5W Star.
- High efficiency switching regulator design means minimum battery drain
- Low Battery cutout feature operates at 11.5V
- Input polarity and transient voltage protection
- Output short circuit proof
- Perfect for automotive or marine use.
Recommended for skilled and experienced constructors as some delicate soldering skills are required to complete this project successfully. We include all wiring and construction information as usual.
PIC Polyphonium (Part 2)
In the second part of this PIC-powered Windows programmable musical project, we describe the construction of the LED Display Control Interface. The dot matrix-style module displays the notes that are being played by the Polyphonium. The Note, Octave and relative on-time are shown.
SMS Controller (Part 2)
This Atmel microcontroller based project allows you to control equipment anywhere using SMS (text messaging) and an old Nokia mobile phone and prepaid Simcard account. In Part Two this month, the circuit checking routines and method of use are described.
USE A PREPAY PHONE ACCOUNT ONLY. PLEASE READ CAREFULLY THE SYSTEM LIMITATIONS AND CAUTIONS SECTION IN THE ARTICLE, TO AVOID INCURRING UNNECESSARY EXPENSE ON TEXT MESSAGES.
Also in the April 2007 issue of Everyday Practical Electronics magazine: Ingenuity Unlimited (readers' own circuit ideas); Techno Talk on how automotive electronics look set to change. Circuit Surgery describes active current measurement techniques. Net Work (the Internet column) suggests a biometric USB drive that lets you access your protected websites, with a fingerprint-swipe.
PCB artwork pcb0407.zip
As from July 2013 issue PCB artwork is available free to subscribers only.
Non-subscribers may purchase artwork files for a nominal sum. Please contact our Orders Dept for information or to place an order.
EPE Printed Circuit Boards
We can supply ready-made printed circuit boards (8-digit order codes) to the original design specification via mail order or from our Online Shop.