High-wattage appliances like
electric irons, ovens and heaters
result in unnecessary
power loss if left ‘on’ for hours unnoticed.
Here is a circuit that senses the
flow of current through the appliances
and gives audible beeps every fifteen
minutes to remind you of power-’on’
This is a non-contact version of current
monitor and can sense the flow
of current in high-current appliances
from a distance of up to 30 cm . It uses
transistors in the input to provide very
high input impedance (1.5 T-ohms),
very low input current (10 pA) and
high-speed switching performance.