To All, I need to power an amp that draws just under 1.5 amps at 110 volts. I measured the current it draws when powered from my variac. The voltage to the amp should be within 5% according to the documentation. The voltage in my house measures 122 volts to 126 volts, varying during the day. So bucking 12 volts should be fine. I am looking at a 120 volt to 12 volt center tapped 5 amp rated xmfr at PartsExpress. The VA of the xmfr is not listed in the description. I want to connect this xmfr in buck configuration. Since I will be bucking 12 volts at approx 1.5 amps this equals 18 VA. At least that's how I remember how to calculate VA from connecting big buck xmfrs to one of my machines several years ago. I think the 12 volts at 5 amps secondary means that the xmfr is 60 VA. But I'm not sure because it is center tapped. It shouldn't make any difference, right? If I used the center tap and just bucked 6 volts then the VA rating would be 30, wouldn't it? Thanks, Eric

- posted
5 years ago