LED
Flashlights - Two dazzling designs for LED torches, featuring a simpler
hi-bri red LED version suitable for reading by, and a more sophisticated
switched-mode circuit for an ultra-bright white LED version. Battery operated,
efficient portable designs sure to impress your friends.
Perpetual
Projects Continuing with our mini circuits which use a modest solar
panel to charge a "Gold Cap" capacitor during the day, which in
turn powers a mini circuit "for ever"! This month a Loop Burglar
Alarm, Touch Door Light (illuminates e.g. a keyhole at night for a short
duration) and Perpetual Rain Alarm are described, based on the solar-power
supply of the July issue.
Water
Monitor - How much does it cost to keep your garden watered? To find
out, build our Water Monitor, a PIC-controlled water flow measurement and
auto shut-off device. You can also program in the cost of water per cubic
metre and the Water Monitor will display the cumulative water consumption
and cost on its LCD display. Requires PIC16F84 (source code available free
from EPE's FTP site), plus an RS WaterFlow Sensor/ Solenoid Valve. 12V d.c.
operated.
50
or 60 Hz Synchronous Clock Driver - due to popular demand, we present
a dual frequency mains circuit which converts 230V a.c. 50 Hz British mains
supply to a 115V a.c. 60Hz one suitable for powering imported synchronous
clocks. Can also be modified for use overseas, to operate British 230V 50Hz
equipment on a 115V 60Hz supply. Also in this issue, Ingenuity Unlimited (readers' own circuit ideas), New Technology Update trends in component package sizes. Circuit Surgery describes the use of decoupling capacitors in parallel. Net Work — The Internet Page — looks forward to satellite internet connections.Special feature — Controlling Flight — an insight into how electronics helps maintain air safety.