In the late 80's SCR units were improved, and a new switching unit was developed - the power cube. This power cube or solid-state-relay (SSR) includes two SCR units and an optocoupler, installed in a hybrid electronic circuit. The optocoupler is a miniaturized control system which combines a light emitting device (LED) with a phototransistor. The control signal causes the LED to emit light, and the phototransistor reacts to the light and switches the SCR on. This system enables a more precise control, since the optic control signal is isolated from the mains and their destabilizing effect on electronic signals. The power cube is a small component which is easy to install and relatively inexpensive. Maintenance of the dimmer is considerably easier, as in case of failure, the entire power cube is simply replaced. Power cubes have become the standard switching device used in most dimmers. A typical power cube units installed in a Compulite dimmer.

Zero – Crossing

The zero crossing mechanism can be susceptible to false triggering from noise on the power time. This can cause completely unpredictable behavior as flashing, pulsing or half-waving.

Noise (Lamp/Dimmer/Choke/RFI)

SCR switching systems can generate considerable noise - both acoustic and electromagnetic, a result of the abrupt and frequent interruptions in the current wave. The frequent switching causes the filament to vibrate, creating a hum known as lamp singing, it also reduces the lamp life. Another unsolicited by-product of the switching, is electromagnetic noise which can cause disturbances to various electrically powered systems which are susceptible to electromagnetic interference. This is especially apparent in sound systems which respond audibly to radio frequency interference. One of the solutions commonly implemented is the connection of sound systems to separate power lines which are not part of the lighting system.