[Boatanchors] Are 400 Hz variac's good for anything but a real 'boat anchor'

[Scott Johnson]

John-
To append the last rely, don't throw it out-it is still a nice toroidal
inductor, and can be used to advantage in filter circuits, and even hefty
DC/DC converter by adding a secondary winding.  I have made spot welding
transformers from standard 10A 60Hz variacs by removing the slider,
insulating the exposed winding with insulating varnish, and winding on a few
turns of welding cable, for example, a 120v 10 A variac yielded a 5V 200 A
spot welder, and the variac was junk anyway, since it had been dropped and
all the bakelite and cast aluminum was broken.  Winding a few turns of heavy
(or bi/tri filar) wire, center tapped, will allow you to make that 400Hz
unit into a 12VDC step up converter transformer, add feedback windings and a
couple of beefy FETs, and yer done!

Scott W7SVJ

-----Original Message-----
From: boatanchors-bounces at puck.nether.net
[mailto:boatanchors-bounces at puck.nether.net] On Behalf Of John Hurst
Sent: Sunday, July 17, 2011 8:58 AM
To: 'Robert Groh'; 'Boatanchors List'
Subject: Re: [Boatanchors] Are 400 Hz variac's good for anything but a real
'boat anchor'

The issue is core saturation. If you run it at a lower input voltage, 18 V
or so you can still run it at 10 amps out. It's still not too useful, but
you could use it with a transformer for a variable filament supply or low
voltage power supply.

60/400*120V = 18V

John,KU6X

-----Original Message-----
From: boatanchors-bounces at puck.nether.net
[mailto:boatanchors-bounces at puck.nether.net] On Behalf Of Robert Groh
Sent: Saturday, July 16, 2011 8:59 PM
To: Boatanchors List
Subject: [Boatanchors] Are 400 Hz variac's good for anything but a real
'boat anchor'

Some wise guy at a hamfest today left me a 120 V, 10A, 400 Hz variac as a
'present'.  I know darned well you can't pull much amperage out of them due
to the small core saturating but can you pull much of anything in amps? I'm
inclined to just yank off the knob and dial scale and pitch the rest.

By the way, if anyone wants this for the cost of shipping, they can have it.

73
Bob, WA2CKY
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