Chapter Questions
Refer to Example $5-I$ and Fig. $5-I$. Assume that $I_{F S}=1 \mathrm{~mA}$ and meter winding resistance $R_m=1 \mathrm{k} \Omega$. If $E_i=-1.0 \mathrm{~V}$ and $R_i=1 \mathrm{k} \Omega$, find (a) $I_m$; (b) $V_o$.
A I-mA movement, with $R_m=1 \mathrm{k} \Omega$, is to be substituted in the circuit in Fig. 5-2. Redesign the $R_i$ resistors for full-scale meter deflection when (a) $E_i= \pm 6 \mathrm{~V} \mathrm{dc;}$ (b) $E_i=$ $6 \mathrm{~V} \mathrm{rms} ;$ (c) $E_i=6 \mathrm{~V} \mathrm{p-p;} \mathrm{(d)} E_i=6 \mathrm{~V}$ peak.
In Fig. P5-3 complete the schematic wiring between op amp, diodes, and milliammeter. The current through the meter must be steered from right to left.
Calculate a value for $R_{i d c}$ in Fig. P5-3 so that the meter reads full scale when $E_i=5 \mathrm{~V}$ and the range switch is on the $5-\mathrm{V}$ position.
Consider that the range switch is in the 5-V position in Fig. P5-3. Calculate values for the following resistors to give a full-scale meter deflection of $5 \mathrm{~V}$ : (a) $R_{\text {irms }}$ for $E_i=5 \mathrm{~V} \mathrm{rms}$; (b) $R_i$ p-p for $E_i=5 \mathrm{~V}$ p-p; (c) $R_i$ peak for $E_i=5 \mathrm{~V}$ peak.
With the circuit conditions shown in Problem 5-4, (a) which diodes are conducting? (b) Find $V_o$. Assume that diode drops are $0.6 \mathrm{~V}$.
For the constant-current source shown in Fig. P5-7, (a) draw the current direction, the emitter arrow, and state if the transistor is $n p n$ or $p n p$; (b) find $I$; (c) find $V_L$.
If $V_o=11 \mathrm{~V}$ and $E_i=5 \mathrm{~V}$ in Fig. 5-3, find $V_z$.
$I_1$ must equal $20 \mathrm{~mA}$ in Fig. $5-4$ when $E_i=-10 \mathrm{~V}$. Find $R_i$.
Define a floating load.
In Fig. 5-5, $E_2=0 \mathrm{~V}, R=10 \mathrm{k} \Omega$, and $R_L=5 \mathrm{k} \Omega$. Find $I_L, V_L$, and $V_o$ for (a) $E_i=-2 \mathrm{~V}$; (b) $E_1=+2 \mathrm{~V}$.
In Fig. 5-5, $E_1=0 \mathrm{~V}, R=10 \mathrm{k} \Omega$, and $R_L=1 \mathrm{k} \Omega$. Find $I_L, V_L$, and $V_o$ for (a) $E_2=-2 \mathrm{~V}$; (b) $E_2=+2 \mathrm{~V}$.
In Fig. 5-5, $E_1=E_2=-5 \mathrm{~V}$, and $R=R_L=5 \mathrm{k} \Omega$. Find $I_L, V_L$, and $V_o$.
Replace $V_z$ in Fig. 5-6 with a $900-\Omega$ resistor. Find $I_L$.
Sketch an op amp circuit that will draw short-circuit current from a signal source and convert the short-circuit current to a voltage.
A CL5M9M photocell has a resistance of about $10 \mathrm{k} \Omega$ under an illumination of $2 \mathrm{fc}$. If $E_i=$ $-10 \mathrm{~V}$ in Fig. 5-9, calculate $R_f$ for an output $V_o$ of $0.2 \mathrm{~V}$ when the photoconductive cell is illuminated by $2 \mathrm{fc}$.
Change multiplier resistor $m R$ in Fig. 5-10 to $49 \mathrm{k} \Omega$. Find $I_L$.
A solar cell that has a maximum short-circuit current of $0.1 \mathrm{~A}=I_{S C}$ is installed in the circuit in Fig. $5-12$. (a) Select $R_F$ to give $V_o=10 \mathrm{~V}$ when $I_{S C}=0.1 \mathrm{~A}$. (b) A $50-\mu \mathrm{A}$ meter movement is to indicate full scale when $I_{S C}=0.1 \mathrm{~A}$. Find $R_{\text {scale }}$ if $R_M=5 \mathrm{k} \Omega$.
Resistor $R_i$ is changed to $10 \mathrm{k} \Omega$ in Example 5-14. Find the phase angle $\theta$.
Design a phase shifter to give a $-90^{\circ}$ shift at $1 \mathrm{~Hz}$. Choose $C_i$ from $0.001,0.01,0.1$, or 1.0 $\mu \mathrm{F}$. $R_i$ must lie between 2 and $100 \mathrm{k} \Omega$.
Design a $-90^{\circ}$ phase shift at $1590 \mathrm{~Hz}$. Then for your design, calculate (a) $\theta$ at $15 \mathrm{~Hz}$; (b) $\theta$ at $15 \mathrm{kHz}$.
Calculate the net current through $R_f$ in Fig. 5-14(a) if the AD590 temperature is $100^{\circ} \mathrm{C}$. Then find $V_o$.
Calculate the net current through $R_f$ in Fig. $5-14(\mathrm{~b})$ when the temperature is $100^{\circ} \mathrm{F}$. Find $V_o$.
Calculate the value of $R_f$ in Fig. 5-14(a) to design a signal conditioning circuit that interfaces with a microcontroller's $A / D$ converter. The voltage range of the converter is 0 to $5 \mathrm{~V}$.
Use a simulation program and design an integrating circuit. The input sugnal is$$e_{\text {in }}=1 \sin 2000 \pi t \mathrm{~V}$$
Use a simulation program and design a differentiating circuit. The input signal is (a) sine wave of $500 \mathrm{~Hz}$ and a peak value of $0.2 \mathrm{~V}$; (b) square wave of $500 \mathrm{~Hz}$ and a peak value of $0.2 \mathrm{~V}$; (c) cosine wave of $500 \mathrm{~Hz}$ and a peak value of $0.2 \mathrm{~V}$.