Chapter Questions
What are the operating modes of the 555 timer?
In Fig. 13-6(a), $R_A=R_B=10 \mathrm{k} \Omega$ and $C=0.1 \mu \mathrm{F}$. Find (a) $t_{\text {high }}$; (b) $t_{\text {low }}$; (c) frequency of oscillation.
Using the graph of Fig. 13-7, estimate the free-running frequency of oscillation $f$ if $\left(R_A+\right.$ $\left.2 R_B\right)=1 \mathrm{M} \Omega$ and $C=0.02 \mu \mathrm{F}$.
What is the duty cycle in Problem 13-2?
In Example 13-1, $R_A$ and $R_B$ are increased by a factor of 10 to $68 \mathrm{k} \Omega$ and $33 \mathrm{k} \Omega$. Find the new frequency of oscillation.
In Fig. 13-8, $R_A$ and $R_B$ are each reduced to $5 \mathrm{k} \Omega$. What is the effect on (a) the duty cycle; (b) the period $T$ of the output?
In Fig. 13-9, at what value should the $10-\mathrm{k} \Omega$ resistor be set for a $2-\mathrm{kHz}$ output from the $B$ 555 ?
Capacitor $C$ is changed to $0.1 \mu \mathrm{F}$ in Fig. 13-10. Calculate (a) the center frequency $f_c$ when $E=0 \mathrm{~V}$; (b) the frequency shift for $E= \pm 2 \mathrm{~V}$.
In Fig. 13-11(a), $R_A=100 \mathrm{k} \Omega$ and $C=0.1 \mu \mathrm{F}$. Find $t_{\text {high. }}$.
$R_A$ is changed to $20 \mathrm{k} \Omega$ in Example 13-5. Find $t_{\text {high }}$.
In Example 13-6(b), what value of $R_A$ is required to divide a 1-kHz signal by 2 ?
Refer to Example 13-7. How long will the following output terminals stay low? (a) pin 1; (b) pin 2; (c) pin 5; (d) pin 6 .
In Fig. 13-16(a), $T$ is set for $1 \mathrm{~ms}$ and pins 2, 4, 6, and 8 are connected to the output bus. Find the timing interval.
In Problem 13-13, the odd-numbered pins, 1, 3, 5, and 7, are connected to the output bus. Find the timing interval.
In Example 13-9, $C$ is changed to $0.1 \mu \mathrm{F}$ and $R$ to $500 \mathrm{k} \Omega$. Find (a) the time base period; (b) the timing cycle for switch positions shown in Fig. 13-18; (c) the maximum timing cycle.
In Example 13-10, what frequencies are present at pins (a) 5 ; (b) 6 ; (c) 7 ; (d) 8 ?
In Fig. 13-21, only switches to pins 1,2,3, and 4 are closed. Find the output frequency.