[sudo-discuss] 120V isolation transformer?

[Jake]

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 at spaz.org> wrote:
>
>> https://en.wikipedia.org/wiki/Voltage_regulator#Constant-vol
>> tage_transformer
>>
>> On Wed, 24 Aug 2016, hol at 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 at 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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>>>>>
>>>>
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