BSR Controls

The smallest stand-alone trigger in the world can fire the largest thyristor you would ever use!

ezytrigger logo


  • The AT 416 EZYTrigger converts high-voltage thyristors (up to 8KV) into optically controlled devices
  • The unit triggers with only 10mA into a fibre-optic transmitter diode
  • Required gate current is derived from the anode of the thyristor via a controlled current source of 2.5A
  • There is no need for an additional isolated power source for gate drive

The unit should be mounted in close proximity to the thyristor with leads as short as possible. If the unit is mounted directly on the heatsink, it is recommended that it be positioned on the heatsink with the same potential as the cathode of the thyristor. This minimizes interference from fastrising high-voltage spikes from the mains. For the same reason, other leads should be kept away from the body of the trigger unit.

Although the unit will operate successfully with the minimum control current of 5mA, it is recommended that the control current be increased to 10mA to allow for ageing of the optical components. If simultaneous triggering is required for a number of series-connected thyristors, it is advisable to use pulse shaping for the transmitter input. An RC network with a time constant of 10μs can be used to create an initial current of 20mA, decaying to 10mA. It is also advisable to maintain the control signal during the required conduction period of the thyristor.

Thyristor Trigger

Thyristor Trigger


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BSR Controls CC - South Africa . P.O.Box 427 . Clanwilliam . South-Africa . 8135 . +27 27 482 1611