Figure P2.43 shows how a BJT can be used to turn on a light-emitting diode (LED) under the control of a logic signal A. Specifi cally, when A 5 L (5 0 V) the BJT is off, and so is the LED; when A5H (5...

Figure P2.43 shows how a BJT can be used to turn on a light-emitting diode (LED) under the control of a logic signal A. Specifi cally, when A 5 L (5 0 V) the BJT is off, and so is the LED; when A5H (5 5 V) the BJT saturates and the LED glows. (a) Assuming the BJT has F(min) 5 50, VBE(sat) 5 0.8 V, and VCE(sat) 5 0.1 V, specify standard 5% values for R1 and R2 to make the LED glow with a current ID 5 10 mA and a voltage drop VD 5 1.5 V. (b) Design a circuit that accepts a logic input B and causes the LED to glow when B 5 L (5 0 V), but causes it to be off when B 5 H (5 5 V).