The switching command for the
SCR
is provided by low-votage
electronic control
signals or by digital signals when the
lighting control
system is computerized. These are very small currents of low-voltage generated by the potentiometers of the lighting
control board
and are typically around 10V. The
control signal
is responsible for the ignition circuit, or driver, of the dimmer which switches the SCRs on.
When the signal is at full voltage, the dimmer will produce the full rated
voltage
(100%), and when the signal is at half, the dimmer will produce half of the rated
voltage
(50%).
Because of this direct relationship between the
control signal
and the
voltage
produced by the dimmer,
SCR
dimmers are called analogue dimmers.
The driver's function is to translate the
voltage
sent by the
potentiometer
into switching commands for the SCR. The driver also functions as a sort of pacemaker, synchronizing the operation of the two SCRs so that their ignition is at the same point in time relative to the beginning of each cycle.
