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joebog1 · 11th Feb 2018, 11:32 pm

Once the transformer has "charged up" to maximum flux the current should be very low, magnetising current only in fact. The transformer is 40 watts, but say its inefficient we can call it 50 watts. Magnetising current should be so small the lamp limiter ( depending on bulb wattage) shouldnt glow. I would " expect" maybe 3 or 4 watts for magnetising current only.
As far as the hum goes, it may be that the case its mounted in is making the noise ??
The last is just a suggestion.

Joe

11th Feb 2018, 11:32 pm	#11
joebog1 Banned Join Date: Jun 2015 Location: Mareeba, North Queensland, Australia Posts: 2,704	Re: HV PSU Question Once the transformer has "charged up" to maximum flux the current should be very low, magnetising current only in fact. The transformer is 40 watts, but say its inefficient we can call it 50 watts. Magnetising current should be so small the lamp limiter ( depending on bulb wattage) shouldnt glow. I would " expect" maybe 3 or 4 watts for magnetising current only. As far as the hum goes, it may be that the case its mounted in is making the noise ?? The last is just a suggestion. Joe