When I measured the input resistance of some 230V AC to 12V DC transformer based power adapters, I got around 400 ohms. Isn't this quite high for the resistance of the primary winding? I expected no more than 100 ohms. The adapters are low power though (output power< 10W).
(Background story: I measured this because I heard that one way to distinguish transformer based power supplies from switched mode power supplies is to measure the input resistance. A transformer based power supply has a transformer at the input side, so you will measure the resistance of the primary winding. With a switched mode power supply, you would measure infinite or mega-ohms resistance because of the rectifier bridge and converter.)
(Background story: I measured this because I heard that one way to distinguish transformer based power supplies from switched mode power supplies is to measure the input resistance. A transformer based power supply has a transformer at the input side, so you will measure the resistance of the primary winding. With a switched mode power supply, you would measure infinite or mega-ohms resistance because of the rectifier bridge and converter.)