Theory

• Firing circuit is the simplest method to understand the firing or triggering circuit of SCR.





• The limited range of firing angle control is from 0˚ to 90˚.





• The potentiometer setting of variable resistance determines the gate voltage amplitude.





• This variable resistance increased from small value, firing angle increases because the firing angle is proportional to variable resistance.





• The half wave power output can be controlled only for 50% in this R firing circuit.





• Circuit Diagram of R firing circuit
  
  

  

  Figure 1





• The R firing circuit is shown in Figure 1.





• The corresponding stimulation waveform is shown in Figure.