Question 5.12: Figure 5-22a shows a voltage-polarity tester. It can be used...

Electronic Principles

Figure 5-22a shows a voltage-polarity tester. It can be used to test a dc voltage of unknown polarity. When the dc voltage is positive, the green LED lights up. When the dc voltage is negative, the red LED lights up. What is the approximate LED current if the dc input voltage is 50 V and the series resistance is 2.2 kΩ?

5-22a

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