PHYS 228 Final, Spring 1996

: é June 29,1996 n iq f-. a) Sketch the digital signal waveforms corresponding to the binary ‘numbers A= 1101,B = 1001 : . and theirarithmetic sum A + B. ‘b) Compare the waveform of the sum to the output waveform of an AND gate with A and B as input - ignals.- “in. a) Using only NAND gates, devise a circuit to perform OR logic., b) Using only NOR gates, devise a circuit to perform AND logic. t t J LE1- What vatue should R be in Fig. | (see last page) to set up a diode current of 0.25 mA? IV- Figure 2 has these circuits values: V,=18V, V.=10V, R, = 270Q, and R, = 1kQ. ‘ 1 (a) ts the zener diode operating in the breakdown region? (b) IF so, what does the zener current equal? > V- (a) Determine the collecter-emitter voltage for the transistor in Fig.3, (b) What advantage does such a circuit configuration present, as far as the transistor is concemed’? at t “VIF The transistor switch circuit shown in Fig.4 is used to control the current through a relay coil. ~ The relay coil has a resistance of 200 Q and requires 20 mA to operate. - a) Does the transistor have to be in saturation to energize the relay coil? Explain. b) Ifa +4-V signal at the control input is to turn the relay on, what current is drawn from the source Virion = 0-6 V)? Pome {Nap -c) What is the minimum value of B that the transistor must have to operate the relay? / Lp et , Vif» Evaluate £,,, in the circuit shown in Fig.S,as a funetion of lime, for the marked values of circuit components, | VIEEL- Write the expression for the output voltage in terms of the input voltages for the circuit shown in Fig.6. hoot IX- What is the output voltage of the Op-Amp circuit in Fig.7? ‘$4ay ov tL 10 kf Conot u input Fig 4 a eles contacts Retas coll R