BY CARLOS COSSIO
There are still millions of older
and not so old appliances that
waste too much energy in
standby mode. The device
described here helps to save
energy without compromising
Most of today’s home appliances have no genuine off switch. They are instead equipped
with standby circuitry over which users have no
direct control. The main power switch controls only
the low voltage circuitry and even when the machine
appears to be turned off, it is still consuming a few watts
of energy without any purpose.
Although solutions do really exist like the switchable
mains outlet strip, they have a distinct disadvantage in
home entertainment applications: Convenience vanishes if
you can no longer switch the device on or off simply by
zapping it with the remote control handset. Solutions of
this kind have the key advantage that hardly any power is
ever wasted on standby current. The downside is that you
can no longer wake up the appliance with its remote
■ FIGURE 1. This is the Green Standby device in action.
Just plug in the appliance in the back and connect it to the
grid to start saving energy!
control. With these semi-intelligent standby switches, you
need to press an onboard button to rouse them again,
wiping out half the attraction.
The proposed device (see Figure 1) reacts to virtually
any key press of almost every infrared remote control
on the market. It enables you to upgrade an existing
appliance with poor standby characteristics, reducing
standby current very significantly.
It doesn’t need installation or any
The interface to the outside
world comprises a 120 VAC mains
input and output together with
an infrared sensor and a power
supply. When a button is pressed
on the infrared handset and is
registered by the IR sensor, the
signal detector delivers a
trigger pulse to the circuit’s
microcontroller. This operates the
relay and the 120 VAC outlet is
powered. Additionally, current
flow is monitored for a number
of seconds. If the microcontroller
■ FIGURE 2. High level block
diagram of the Green Standby.