The document presents an overview of silicon controlled rectifiers (thyristors), detailing their structure, operation modes, history, and various types. It highlights the applications of thyristors in high voltage and current scenarios, such as electronic circuit control and power stabilization. The presentation emphasizes the significance of thyristors in both practical electric applications and various electronic devices.

1. SCR (Silicon controlled rectifier) - ThyristorPresented by:SNEHASHIS PAUL07/ECE/1093rd year (E.C.E)Batch-2 Supported by CANNONICAL CORP. Please redistribute Linux OS generously.

2. IntroductionThe thyristor is a solid-state semiconductor device with four layers of alternating N and P-type material. They act as bistable switches, conducting when their gate receives a current pulse, and continue to conduct for as long as they are forward-biased.Thyristors have three states of operation:Reverse blocking mode

3. Forward blocking mode

4. Forward conducting mode Circuit symbol of Thyristor:

5. History The SCR or Thyristor was proposed by William Shockley in 1950 and championed by Moll and others at Bell Labs in 1956. it was fabricated by power engineers at General Electric led by Gordon Hall and commercialized by G.E.'s Frank W. Gutzwiller.

6. Construction The thyristor is a four layer, three terminal semiconducting device, with each layer consisting of alternately N-type or P-type material, for example P-N-P-N.The main terminals, labelled anode and cathode, are across the full four layers and the control terminal, called the gate, is attached to P-type material near to the cathode. The thyristor has three P-N junctions serially named j1,j 2,j 3 from the anode.

7. Static Switching Characteristics

8. Dynamic Switching Characteristicsto n – Turn-on time

9. Va – Anode voltage

10. Ia - Anode current