A 6 V DC source is connected through resistor R₁ = 330 Ω to a node X. From node X to the source’s negative terminal there are two parallel paths: resistor R₂ = 680 Ω, and a silicon diode with its anode at X. Use the constant-drop model with 0.7 V. Find the diode current ID in mA.
A white LED with a forward voltage of 3 V runs from a 5 V supply through a series resistor. Find the resistance R that sets the LED current to 5 mA.
An NPN transistor with β = 120 has voltage-divider bias from VCC = 15 V: R₁ = 68 kΩ from VCC to the base and R₂ = 22 kΩ from the base to ground. The collector resistor is RC = 3.3 kΩ and the emitter resistor is RE = 1.2 kΩ. Take VBE = 0.7 V and use the Thévenin equivalent of the divider (do not neglect the base current). Find the collector current IC in mA.
An NPN transistor with β = 150 has voltage-divider bias from VCC = 20 V: R₁ = 82 kΩ from VCC to the base and R₂ = 10 kΩ from the base to ground. The collector resistor is RC = 5.6 kΩ and the emitter resistor is RE = 1.5 kΩ. Take VBE = 0.7 V and use the Thévenin equivalent of the divider (do not neglect the base current). Find the collector–emitter voltage VCE.
A 3.3 V Zener regulator must supply up to 40 mA to a load. The input can drop to 18 V, and the Zener needs at least 2 mA to regulate. Find the largest series resistance Rmax that keeps it regulating.
A 3.3 V Zener regulator must supply up to 10 mA to a load. The input can drop to 24 V, and the Zener needs at least 2 mA to regulate. Find the largest series resistance Rmax that keeps it regulating.
Full step-by-step solutions: practise this topic on examproblems.com.