[rescue] Re: 48v 15 amp power supply kit?

Michael Thompson m_thompson at ids.net
Wed Aug 6 07:18:57 CDT 2003

There is reason that the -48VDC telecom power supplies are expensive. They
are really rectifiers not power supplies. They are designed to be connected
to the DC load and a string of lead acid batteries. The battery charging
circuitry is fairly complex and varies the charging current based on
available power and the battery's temperature. It also has a low voltage
disconnect relay and alarm circuits.

Telecom equipment is designed to run at a minumum of -36VDC and a maximum
of -58VDC or -72VDC. If you can find an unregulated -48VDC power supply
that doesn't have a battery charging circuit it should be inexpensive. Take
a look at some of the feroresonant designs.

>Me and a buddy and toying around with the idea of building a rack mount
>AC-to-DC power supply.
>We thought if there was enough interest we could throw some kits
>together for other interested gear-heads.  We'd prolly have to see it as
>a kit (minimal soldering and assembly), but most of the stuff would be
>Is this anything that people would be interested in?
>What features would you like to see?
>We're shooting for a price between $130 and $200 depending on how much
>regulation and power conditioning we have to build in.
>p.s. He's an EE freak and I did some ac-to-dc stuff in school.

Michael Thompson
E-Mail: M_Thompson at IDS.net

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