Strand System CRD is based on a 30 channel Trinistor (Silicon Controlled Rectifier) unit. The channels have a capacity of 2.5 or 5kW. For 10kW, two channels are connected in parallel. Dimmers are load independent and provided with overload and surge protection. A high degree of clean-up is provided to neutralise any undesirable effects of the chopped waveform.

Three control desk systems are available to use with multiples of the standard CRD/R 30 channel racks:

• a. Standard CRD: two or four presets as schedule below with tablet switches to allow formation of 3 groups within the presets (illustrated right).
• b. Luminous CRD/L: as above but with new type internally illuminated dimmer levers giving colour display to identify groups selected. Particularly suitable for large theatre or opera installations or 200 or more channels.
• c. Memory Group C/AE: this system combines the luminous levers of CRD/L above with an automatic memory relay in such a way as to realise in an all-electric form the full range of control so long available in Strand electro-mechanical systems CD and C. Particularly suitable for control of television production lighting. (Patent applied for).