A 5 V DC source is connected through resistor R₁ = 1.5 kΩ to a node X. From node X to the source’s negative terminal there are two parallel paths: resistor R₂ = 10 kΩ, 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 12 V Zener diode is fed from 15 V through a 330 Ω resistor, with no load connected. Find the current IR in the resistor.
An NPN transistor with β = 200 has voltage-divider bias from VCC = 20 V: R₁ = 47 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 current IC in mA.
A 5.1 V Zener regulator is fed from 20 V through 330 Ω and supplies a 1000 Ω load. Find the Zener current IZ.
A 3.3 V Zener regulator has a 680 Ω series resistor. The input can rise to 13 V, and the load may be disconnected. Find the largest power PZ,max the Zener must dissipate.
An NPN transistor with β = 200 switches a 100 Ω load resistor connected between VCC = 9 V and its collector. The emitter is grounded. The base is driven from a 3.3 V logic output through a base resistor RB. Take VBE = 0.7 V and VCE(sat) = 0.2 V. For reliable switching, design for a base current 4 times the minimum needed for saturation. Find RB in kΩ.
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