Electronics > Beginners
wierd resistor
boy2018:
i would be very happy if someone could help me with this one to find out what is the fuction of this resistor
ArthurDent:
There is capacitance coupling between the primary and secondary of the transformer and the secondary will float at some voltage unless it is actually referenced to ground. In this case the neutral is ground (earth) potential so a high value resistor, typically 1 to 3 Mohm, will drain this voltage to ground. Often used in laptop or other linear power supplies with no 3rd ground pin on the line cord.
JS:
Bad if something is wired backwards in the mains line, won't hurt you but you will feel it. Luckily for living organisms, resistors like to fail open and not shorted.
JS
boy2018:
--- Quote from: ArthurDent on August 30, 2018, 11:25:40 pm ---There is capacitance coupling between the primary and secondary of the transformer and the secondary will float at some voltage unless it is actually referenced to ground. In this case the neutral is ground (earth) potential so a high value resistor, typically 1 to 3 Mohm, will drain this voltage to ground. Often used in laptop or other linear power supplies with no 3rd ground pin on the line cord.
--- End quote ---
My only issue with that is that the plug terminals weren't polarized, so if you plugged it in upside-down, you'd make everything live at mains potential . So i request someones help with this one :)
Zero999:
The resistor should be a high so the leakage current will be too low to cause a shock, even if the polarity of the mains is reversed.
This resistor is probably used for ESD purposes, i.e. to stop static electricity from building up on something.
What's the power supply from?
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