A 10 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 = 1.5 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 24 V DC source drives current through a 3.3 kΩ resistor in series with two forward-biased silicon diodes. Use the constant-drop model with 0.7 V per conducting diode. Find the current I in mA.
An NPN transistor with β = 200 is biased by a base resistor RB = 1000 kΩ from the supply VCC = 12 V. The collector resistor is RC = 4.7 kΩ and the emitter is grounded. Take VBE = 0.7 V and assume the transistor is in the active region. Find the collector–emitter voltage VCE.
An NPN transistor with β = 80 has voltage-divider bias from VCC = 12 V: R₁ = 47 kΩ from VCC to the base and R₂ = 6.8 kΩ from the base to ground. The collector resistor is RC = 2.2 kΩ and the emitter resistor is RE = 2.2 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.
A diode is modelled as 0.65 V in series with 5 Ω (it conducts above 0.65 V). It is in series with a 470 Ω resistor across a 5 V supply. Find the operating current ID where the diode line meets the load line.
An NPN transistor with β = 100 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 3 times the minimum needed for saturation. Find RB in kΩ.
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