[sudo-discuss] 120V isolation transformer?

[Jake]

ideally you can remove the large useless husk of the microwave as soon as 
you're done so it doesn't clog up sudoroom.  Also i think we probably have 
at least one MOT lying around somewhere, maybe in a file cabinet.

On Thu, 25 Aug 2016, Cere Misc wrote:

> I'll volunteer to take apart the microwave (see them on the street all the
> time). Never taken apart a microwave before.
>
> On Aug 25, 2016 2:32 PM, "Jake" <jake at 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 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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>