Converting a 12VDC 20A switched PSU to 12V AC , possible ?

hi guys, I have some nice switched supplies from a server rack, 12VDC 20A .
I need an AC source , roughly 12V 20A. I wonder if it would be possible to just rip out some rectifier parts and have a powerful AC supply , just like you can do with a linear supply.
thanks in advance , Dre

permeke:
hi guys, I have some nice switched supplies from a server rack, 12VDC 20A .
I need an AC source , roughly 12V 20A. I wonder if it would be possible to just rip out some rectifier parts and have a powerful AC supply , just like you can do with a linear supply.
thanks in advance , Dre

At what AC frequency do you require? Your switching PSU runs at several kHz. and is NOT using a sine wave to generate the voltage being rectified and filtered to give DC.

Paul

And what is the magical device that needs 12V 20A AC?

well, I need to drive a large electromagnet for resonating purposes

What are the specs of that "electromagnet"
Maybe a >=250watt class-D car booster amplifier can be used.
Leo..

Wawa:
What are the specs of that "electromagnet"
Maybe a >=250watt class-D car booster amplifier can be used.
Leo..

maybe that's not such a bad idea.
Need to measure but the coil is 3 ohm something so a 1000W amp could do

permeke:
hi guys, I have some nice switched supplies from a server rack, 12VDC 20A .
I need an AC source , roughly 12V 20A. I wonder if it would be possible to just rip out some rectifier parts and have a powerful AC supply , just like you can do with a linear supply.
thanks in advance , Dre

No. Definitely no. SMPS are complex beasts and the whole circuit feedback loop relies on the DC
output rail being sampled and compared to a reference voltage.
And anyway the switching frequency will be way above what you are expecting for 12VAC and totally
inappropriate for an electromagnet.

Why is a simple 12V output mains transformer not suitable? Just cost?

MarkT:
No. Definitely no. SMPS are complex beasts and the whole circuit feedback loop relies on the DC
output rail being sampled and compared to a reference voltage.
And anyway the switching frequency will be way above what you are expecting for 12VAC and totally
inappropriate for an electromagnet.

Why is a simple 12V output mains transformer not suitable? Just cost?

good question. I need to find a 12V 30A trafo

Wawa:
What are the specs of that "electromagnet"
Maybe a >=250watt class-D car booster amplifier can be used.
Leo..

Hey Wawa, did a simple test and I must say it works pretty good .

One question though, do I need a kind of snubber circuit on the coil to protect the amp ?
my childish brain says no since a speaker coil does the same.

If the amp is ready made aka designed to drive a speaker, no. Probably has clamping diodes to the rails already.