Most homes today have at
least a few infrared remote controls, whether they be for the
television, the video recorder, the stereo, etc. Despite that fact, who
among us has not cursed the light that remained lit after we just sat
down in a comfortable chair to watch a good film? This project proposes
to solve that problem thanks to its original approach. In fact, it is
for a common on/off switch for infrared remote controls, but what
differentiates it from the commercial products is the fact that it is
capable of working with any remote control.
Therefore, the first one you find allows you to turn off the light
and enjoy your movie in the best possible conditions. The infrared
receiver part of our project is entrusted to an integrated receiver
(Sony SBX 1620-52) which has the advantage of
costing less than the components required to make the same function.
After being inverted by T1, the pulses delivered by this receiver
trigger IC2a, which is nothing other than a D flip-flop configured in
monostable mode by feeding back its output Q on its reset input via R4
and C3. The pulse that is produced on the output Q of IC.2A makes IC.2B
change state, which has the effect of turning on or turning off the LED contained in IC3.
This circuit is an opto triac with zero-crossing detection which
allows our setup to accomplish switching without noise. It actually
triggers the triac T2 in the anode where the load to be controlled is
found. The selected model allows us to switch up to 3 amperes but
nothing should stop you from using a more powerful triac if this model
turns out to be insufficient for your use. In order to reduce its size
and total cost, the circuit is powered directly from the mains using
capacitor C5 which must be a class X or X2 model rated at 230 volts AC.
This type of capacitor, called ‘self-healing’, is the only type we
should use today for power supplies that are connected to ground.
‘Traditional’ capacitors, rated at 400 volts, do not really have
sufficient safety guarantees in this area. Considering the fact that the
setup is connected directly to the mains, it must be mounted in a
completely insulated housing. A power outlet model works very well and
can easily be used to inter-space between the grounded wall outlet and
that of the remote control device.
Based on this principle, this setup reacts to any infrared signal
and, as we said before, this makes it compatible with any remote
control. On the other hand, it has a small disadvantage which is that
sometimes it might react to the ‘normal’ utilization of one of these,
which could be undesirable. To avoid that, we advise you to mask the
infrared receiver window as much as possible so that it is necessary to
point the remote control in its direction in order to activate it.
Author: Christian Tavernier – Copyright: Elektor Electronics Magazine