Tuesday, November 30, 2010

Another variac/variable DC supply for the bench, this one shows the mark of DIY so I figure I should check it out before using it.

We have no need of sleek, streamlined bullshit here.

I begin to wonder if this wasn't completely thrown together by someone, as the 200 VA 24 volt step down transformer (in black) and and huge choke are designed to carry current far in excess of what the 2.25 amp autotransformer can deliver (2.25 amps being its design limit no matter what voltage it delivers).

The rectifier for the DC side illustrates gargantuan over design..

..while the profusion of electrical tape and some of the taps illustrate haste. This thing is certainly a cobbler hammered out on some freaks workbench, should be right at home once I dress the bare wires and introduce it to some compressed air.

Here's a nice hook-up diagram for a variable autotransformer. Wall voltage is wired across either 1 and 2 (allowing a 0-120 volt range) or 1 and 4 (allowing a step up to 0-132 volt range) actual voltages are going to hinge what you have at the wall, the 1-2 = 100% and 1-4 = 110%. Output is at terminal #3 (variable hot) and terminal #1 (neutral).

Here's a shot of the markings on the choke, mainly because I like the distortions incurred by taking a shot through the perforated steel.


the road dogg said...

Really enjoying these posts.

crochambeau said...

Thanks! I'm enjoying writing them, makes for a good combo.