Hi All,
Recently I started to learn electronics, and saw a measurement method to determine GND and VCC pin.
So basically there is a few unknown pins on a PCB circuit. The guy first used a multimeter to probe the pin against GND and measured a resistance value of 0 ohm. Next, he probe the same pin against a VCC point on the board from a IC chip. The measurement is 100 ohms. Lastly, he switched on the device, and measured the voltage of the pin to be 0V. He went on to derived that the pin is actually a GND pin.
Similarly, the guy used a multimeter to probe another pin against GND and measured a resistance value of 100 ohms. Next, he probed the same pin against a VCC point on the board from a IC chip. The measurement is 0 ohm. Lastly, he switched on the device, and measured the voltage of the pin to be 3.3V. He went on to derived that the pin is actually a VCC pin.
I thought about it but still could not wrap my head around how this method works.Would you guide me to understand the logic behind it? Thank You.
Recently I started to learn electronics, and saw a measurement method to determine GND and VCC pin.
So basically there is a few unknown pins on a PCB circuit. The guy first used a multimeter to probe the pin against GND and measured a resistance value of 0 ohm. Next, he probe the same pin against a VCC point on the board from a IC chip. The measurement is 100 ohms. Lastly, he switched on the device, and measured the voltage of the pin to be 0V. He went on to derived that the pin is actually a GND pin.
Similarly, the guy used a multimeter to probe another pin against GND and measured a resistance value of 100 ohms. Next, he probed the same pin against a VCC point on the board from a IC chip. The measurement is 0 ohm. Lastly, he switched on the device, and measured the voltage of the pin to be 3.3V. He went on to derived that the pin is actually a VCC pin.
I thought about it but still could not wrap my head around how this method works.Would you guide me to understand the logic behind it? Thank You.
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