### Digital Electronics Objectives Part 12

221 . The segments of a seven-segment display are lettered to a clockwise direction.

222 . Current drawn when the number 8 is on an LED display is 140 mA.

223 . Current supply to a four-digit liquid crystal display that reads the number 8888 is of the order of 560 nA.

Question 224 to 227 is from fig 37

224 . Boolean expression for the output of f1 is A.

225 . Boolean expression for the output of f3 is A𝑩.

226 . Boolean expression for the output of f4 is 𝑨B.

227 . Boolean expression for the output F is A𝑩 + 𝑨B.

228 . For the circuit shown in Fig. 38 F=AB.

229 . For the circuit shown in fig. 39 the ouput F=0 when both f2 and f3 are 1.

230 . The fan out of a 7400 NAND is 10 TTL.

231 . The input of a 7420 four-input NAND gate are VA = 3.9, VB = 4.0, VC = 4.1 and VD = 3.7. the output logic level is 0.

232 . The three inputs on a 7411 AND gate IC are measured to be VA = 3.8, VB = 4.1, and VC = 4.3. The binary level of the output F will be 0.

233 . The A2 input at pin 4 of a 7400 NAND gate is +5V, and the other input B2 at pin 5 is also +5V. the logic level of the inputs and output F2 respectively areA2B2 = 11, F2 = 1.

234 . The inputs of a 7400 NAND gate are VA equals 0.2 V and VB equals 0.35 V. The logic level of output will be F = 1.

235 . In the above case 2.4 would be the minimum voltage that could be measured at F.

236 . 10 is the octal number that come after 7.

237 . 161is the weight of the second hexadecimal digit to the left of the point.

238 . Non of the above conversion is incorrect.

239 . Non of the above conversion is incorrect.

240 . Weight term is used to refer to the positional value of a digit.