July 2007 Issue

A summary of this month's contents.

Video Reading Aid

Displays enlarged text on a TV or video monitor . Our electronic aid is designed for those having impaired sight or those who just want to make life a little easier for themselves. It combines a small monochrome CMOS TV camera with a videoprocessor, which boosts the contrast and allows users to select either a positive or negative enlarged image on a TV or monitor. All details are contained along with full photography in our ten page constructional article.

 

SMD components – good soldering skills are necessary.

 

Digi-Flash Slave

This opto coupled slave flash drive can help you radically improve the results from flash photography, by using a second 'slave' flash triggered by your camera's built in flash. A simple way of enhancing indoor photography or portraiture.

 

MiniCal 5V Calibration Standard

How accurate is your digital voltmeter? Find out with this simple yet accurate DC voltage reference. If your meter fails the grade, the reference can be used as the calibration standard too.

As a bonus, a crystal-locked frequency reference is included that doubles as a crystal checker.

Specification:

  • 5.000V ± 0.02% voltage standard
  • 192.3mV ± voltage standard (optional ±0.1% or ±0.04%)
  • Two ±0.1% resistor standards (optional ±0.01%)
  • Crystal locked frequency reference
  • Crystal checker.

 

Lead-Acid Battery "Zapper"

A simple circuit designed to extend the working life of liquid electrolyte lead acid batteries, by dissolving the lead sulphate crystals that form on their plates.

The circuit is powered by the battery itself or by a charger, and "zaps" the battery with a series of high voltage pulses. It may sometimes rejuvinate some batteries that have sulphated due to lack of use, however it cannot possibly rejuvinate a battery that is simply worn out.

 

HIGH VOLTAGES ARE GENERATED BY THIS CIRCUIT. DO NOT CONNECT DIRECTLY TO A CAR BATTERY IF INSTALLED IN A VEHICLE. PLEASE READ THE ARTICLE WARNINGS CONCERNING THE DANGERS POSED BY HYDROGEN GAS EMITTED BY LEAD ACID BATTERIES.

 

This issue also includes The Power of Mechatronics (Part 2) - controlling motors. Practically Speaking - our handy hints page on semiconductor identification. Circuit Surgery Linear Voltage Regulators and Capacitors (Part 1). Using MPLAB (Part 2); Net Work - the Internet page on the benefits of importing direct from the USA. Ingenuity Unlimited - readers' own circuit ideas.

 

 

PCB artwork pcb0707.zip

 

PCB artwork

 

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.

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