In this video, how the transistor (BJT) acts as a switch is explained with an example. Along with that, it is also explained, how to identify the saturation in BJT and what is Hard Saturation. By watching this video, you will learn the following topics: 0:00 Introduction 1:03 BJT in the Cut-off Region 2:21 How to identify the Saturation in BJT 4:31 Solved Example ( Identify the Region of Operation of Transistor ) 7:10 What is Hard Saturation in BJT 8:07 Solved Example on Hard Saturation 9:40 Transistor (BJT) as a Switch How to Identify that the BJT is operating in Saturation? When the transistor operates in Saturation then the voltage between collector and emitter terminal (Vce) is very low (typically it is 0.1 to 0.2 V), and the collector current Ic is maximum. Steps to Identify the Saturation in BJT : 1) Calculate the Ic(sat), the collector current in the saturation. (Assuming Vce = 0 ) 2) Find the base current Ib. 3) Assuming the transistor is operating in the active region, find the collector current. (Ic = β Ib) 4) If the assumed collector current is more than Ic (sat) then the transistor is operating in saturation. In this video, it is explained with the example. Hard Saturation in BJT: With the change in the external parameters like temperature, or with the replacement of the transistor the β may change. And with that change, the transistor may come out of saturation. So, to ensure the operation of BJT in the saturation region in all the conditions, the β in the saturation should be very low. Typically around 10. I,e β sat should be around 10. That means the values of base and the collector resistors should be selected such that the βsat is around 10. By ensuring this condition, it can be ensured that the transistor will operate in saturation, even if there is a change in the external parameter. Transistor as a switch : By operating the BJT in the cut-off and the saturation region, the BJT can be used as a switch. In cut-off region, the transistor offers high resistance and in saturation, it offers very low resistance. That means in the cut-off region, the BJT will act as an open circuit and in saturation, it will act as a closed switch. In this video, it is explained in detail, how the BJT can be used as a switch. The link of the other useful videos related to BJT (Playlist)    • BJT (Bipolar Junction Transistor)   This video will be helpful to everyone in understanding how the BJT can be used as a switch and how to identify the saturation in BJT. #TransistorAsSwitch #SaturationInBJT #BJTasSwitch #HardSaturation #BJT Follow my second channel: https://www.youtube.com/channel/UCGA2TO8ylVqFHpucwn_6Jlw Follow me on Facebook: https://www.facebook.com/ALLABOUTELECRONICS/ Follow me on Instagram: https://www.instagram.com/all_about.electronics/ Music Credit: http://www.bensound.com/