The No. 1 UK Magazine for electronics technology and computer projects
EPE's web site is ten years old this month! Our Internet service was originally launched in the mid 1990's to provide FTP access to source code files, which we decided to make freely available for downloading at a time when interest in microcontrollers was emerging. A very basic web site was added in 1996, followed by online secure ordering of subscriptions, and then a shopping cart. EPE Online was launched as a downloadable version of the magazine available to anyone with Internet access.
We have uploaded the original version of the EPE web site here.
Studio 350W Power Amplifier Module (Part 1) A superbly designed low distortion amplifier that has some real grunt! The Studio 350 is a rugged power amplifier module capable of delivering 200W r.m.s. into an 8-ohm load and 350W r.m.s. into a 4-ohm load. Frequency response -1dB at 15Hz and 60kHz at 1W. Input sensitivity 1.75V for 200W into 8 ohms. Harmonic distortion typically 0.002% at normal listening levels. S/N -122dB unweighted (22Hz to 22kHz).
In Part One, the design background, technical specifications and oscillograms are given. Constructional details in Part 2, next month.
1 Watt Luxeon LED power supply Want to power one or more Luxeon 1 Watt star white LEDs from a 12V battery or a DC plugpack? This circuit is an experimenter's power supply constructed from standard parts. It allows for dimming as well. It will power up to four 1W Luxeon Stars. Straightforward to build, full constructional details are included. 
Through-Glass Alarm - initially devised to assist traders to comply with the UK Disability Discrimination Act, this device is a close-range proximity sensor that enables e.g. a disabled person to place their hand over a sensor plate that is mounted on the other side of a pane of glass (door/ window).Uses the glass as a capacitor dielectric. Alerts staff inside via a large LED that their attention is required. Vandalproof and weatherproof design, no moving parts, with other applications possible.
Fridge Door Alarm If you have ever forgotten to close a fridge or commercial freezer door fully, you will know how easy it is to spoil food accidentally. Our Fridge Door Alarm is a compact device that detects light that falls in the compartment area. Most fridges have an interior light, but even if it does not, as long as there is some ambient light in the room that the alarm can react to, the unit will operate correctly. The built-in piezo alarm will sound if the ambient light is present for longer than the preset period, and will continue to sound until the door is closed. 
Also in this issue: PIC n MIX - understanding data sheets. Techno Talk - the Quest for green volts. Interface - more on a Visual Approach to producing virtual controls. Circuit Surgery - timing formulae for 555 timers. Net Work (the internet page) on how to destroy personal data on your hard disk. Order your copy now! Available at all good newsstands, or on subscription.