21. Suppose that you wish to observe a 1KHZ sine wave of 0.25V amplitude (0.5 vp
ID: 2291800 • Letter: 2
Question
21. Suppose that you wish to observe a 1KHZ sine wave of 0.25V amplitude (0.5 vp-p). Which of the following would be a good choice for horizontal and vertical scales? A. B. C. D. 10 mS per division horizontal and 3 V per division vertical 100mS per division horizontal and 0.1 V per division vertical 1uS per division horizontal and 0.1 V per division vertical None of these is a good choice vcC R14 VCC VCC 180KO TL072ACP LED1 N4149 C4 10ko 10LuF R7 1 200 Figure 7 22. Given the circuit above, which of the following is plausible? With a suitable choice of component values for R14 and R15, the LED can be made any brightness at full signal, but it may still be on with no signal The value of C4 has no effect on the maximum LED current. The value of the threshold voltage for Q1 is unimportant as long as R7 is chosen correctly Most of the voltage drop in the output circuit consisting of R7, Q1, and LED1 will occur across LED1 A. B. C. D.Explanation / Answer
21 )
For 1kHz sin wave
The time is =1/f
=10-3 seconds
=1 ms
Hence the one with near to 1 ms division in horizontal scale is preffered
Now , for vertical scale
it is given
0.5 V peak to peak
Hence scale with divison of 0.1 V is perfect
However among all the options nothing matches both the above conditioins hence D option is appropiate
Rest according to application Answer may vary
22)
A is correct option because it will decide the value of opamp / comparator output which ultimately drives the circuit hence the brightness is controlled
In B option it is wrong because Voltage due to C4 will Affect Q value
In C option The value of Q is important and with R7 it changes the current in circuit but Q gives the range of current variation
In D option It depends on current and impednace values
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