On Aug 25, 2016 2:32 PM, "Jake" <jake@spaz.org> wrote:

this is definitely a decent way to do it.

microwave transformers are constructed with all the E's on one side and all the I's on the other, and then welded together with a thin bead.  This means that using an angle grinder with an abrasive cutting disk (and safety gear!) you can cut the weld so that you can remove the bottom of the transformer.  Then you remove the high-voltage winding and install another primary winding with a similar number of turns as the original primary.  If you have two identical microwave oven transformers (MOTs) you can just open both and move the primary from one to the other.

If you add a variac you can tune the voltage, but you could also do that by putting multiple connections along the last part of one of the primaries, and then a rotary switch to select between them.

the important part is that the transformer isolates the equipment so that people are less likely to die in your hackerspace.

On Thu, 25 Aug 2016, Cere Misc wrote:

Take apart a microwave and use it’s core to create a isolated set of
windings at whatever ratio then connect it to a variac?

On Wed, Aug 24, 2016 at 3:58 PM, Jake <jake@spaz.org> wrote:

https://en.wikipedia.org/wiki/Voltage_regulator#Constant-vol
tage_transformer

On Wed, 24 Aug 2016, hol@gaskill.com wrote:

Just out of curiosity, can you share a bit more about waveform

distortion?  Was just looking at schematics for a 12-pulse converter and
different winding configurations
https://en.wikipedia.org/wiki/HVDC_converter#Twelve-pulse_bridge
On 2016-08-19 01:24, robb wrote:

ty for trying to save my life, jake

On Thu, Aug 18, 2016 at 11:05 PM, Jake <jake@spaz.org> wrote:

does sudoroom have an isolation transformer?  it's something that plugs

into a regular outlet and outputs the same voltage, but it's isolating.

we have a couple of universal AC converter boxes which provide 240VAC
when you plug them into 120VAC but they are "autotransformers" and they
don't isolate.

I want us to have an isolating transformer so that when people
experiment with AC-powered devices, they are much less likely to suffer a
lethal shock and die.

note:  some voltage-regulator transformers are isolating, but since
they distort the waveform in order to achieve the voltage stabilizing, they
are not ideal for our purposes.

thank you,
-jake
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