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Inverter Transformer As Power Supply

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Just salvaged the transformer from APC UPS BE500-IN 500VA. Can I use it to build a power supply?
My interest on this transformer is for the high current rating (we all need one for high power projects). Should the idea be legitimate, the secondary of the transformer can be connected to AC wall outlet to get at least 12+12VDC 10A current and cut costs on switching power supplies for our laboratories.
The positive terminal of the battery is connected to the centre tap of the 12-0-12V primary alone. Tracing the circuit suggests some half-wave rectifier system keyed from a relay. Obviously, the battery is charged from steeped-down AC wall outlet supply somehow and the absence of any other transformer points to my apprehension.
Please advise...
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Post the schematic of the inverter for us to see if its transformer is big and operates at a low frequency or is small and operates at a very high frequency.

Modern UPS circuits use a tiny ferrite high frequency transformer. It will blow up if connected to the low frequency mains.


Well-Known Member
Yes this can be used.

I salvaged a similar transformer from an old Kensington 1000 VA UPS.

Usually these UPS's use a separate smaller transformer for charging the battery.


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audioguru and RCinFLA, thank you very much for your reply.
The 'transformer is big and operates at a low frequency'. I fed the primary with 50Hz 5-0-5V square wave at 50% duty cycle with 10A maximum current available and the secondary was at...
1. 300V under no load drawing 1A average current at the primary,
2. 275V under Phillips lamp (rated 15W 220V) drawing 2A average current at the primary.
Building an inverter with success, as you see, I need to reverse this phenomenon. What I know is transformers follow reciprocity theorem (constant power at both sides). The DC resistance of primary is 0.01Ohm and secondary is 0.7Ohm (though inductance, and hence AC resistance is unknown).
I had enough of the beginner's fascination with inverters. Now what interests me is a low voltage high current power supply for He-Ne lasers. Interests in resonance, anyone? If not, such a power supply is, still, indispensable.
Please review my former post and advise...
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