A microprocessor based thyristor firing control PCB with both Phase Angle and Burst Firing options.

Suitable for ac/dc resistive/inductive loads, via thyristor pairs on 3-phase stacks
No external phasing transformers required
Analogue control inputs 0-5Vdc and 4-20mA current loop
Digital isolated control, opto-coupled +5 → +25Vdc
Selectable current limit with LED indication
Over-current latching trip to 150% LED indication
Selectable resistive/inductive loads
Selectable phase reversal
Output status indication

The number of complete mains cycles during fixed repeating periods (typically 1 to 10 seconds) is varied, thus altering the duty cycle or on-/off-time ratio. Trigger pulses coincide with the zero-crossing times of the mains supply thus ensuring no RFI is produced when using resistive loads.