Body
Mick! Your comment about some people dying from pranks! True Story!
Back in the early 80s a pastor at a Duncanville Church (suburb of
Dallas) was preforming a live Baptism at his church on a typical Sunday
morning! His audio amp was the old vintage single end class A push-pull
tube amp. As he descended into the Baptism pool in front of
congregation and flipped on the hand held mic switch has was instantly
fried by 450VDC plate voltage on chassis ground. Coroners report showed
that an electrolytic cap in the HVDC plate power supply had gone to
ground in effect energizing chassis at the 450VDC potential. All those
vintage amps had the old two pin 120VAC plugs before the 3 pin safety
grounds we now have.
http://www.angelfire.com/electronic/funwithtubes/Amp-Power_Supply.html
Having gone through DeVry Electronics back in 1953, I totally understood
the lethality of such an event!
On 11/3/2018 7:55 PM, Mick [email protected] [EVGRAY] wrote:
>
> Norm,
>
> The interconnects used for home audio should be illegal for bad sound,
> but even a properly designed mic cable with an XLR on each end with a
> hot a cold and a shield one will notice only on female side the shield
> connects to the chassis of the connector. It is a single shield run
> on #1 to both sides though as the connections are designed balanced
> for just the reason you mentioned.
>
> XLR's are the best connector for long run connections but I make my
> own cable with silver plated aircraft cable with teflon insulation, a
> pain to work with but sound is great.
>
> For short single ended runs the RCA end sucks and it should have been
> BNC or the extra small microwave connectors that look like mini BNC's
> If one removes the RCA connectors and replaces with BNC and high
> quality aircraft cable and the rest of the gear is good enough one
> will notice the difference. Networking cable Cat 5 or 6 can also
> sound great as speaker cable.
>
> The story gets worse though as the old tube guitar amp had a switch
> that would toggle chassis ground between either connector on the power
> connection for the purpose of preventing ground loops when some live
> show venue had the outlets wired with hot and neutral reversed. Well
> when that guitarist also happens to be a vocalist and touched a mic
> stand with the ground switched wrong it was not pretty if the shield
> was run to both chassis of the connectors. This was an old soundman
> trick to get back at the rude ego asshole guitar players using the
> special fully grounded mic cable. I am sure some people died from
> this prank where 220 was used.
>
>
> On 11/3/2018 4:46 PM, Norman Wootan [email protected] [EVGRAY] wrote:
>>
>> Mick! Just had to laugh at your remark about floating grounds in the
>> recording studio! Ha! Ha! Way back when I was learning about fine
>> audio, I ran a shielded line level audio cable to hook two sound
>> systems together, about 100 ft run. When I turned on the systems and
>> selected line in on the 2nd system, I had the prettiest motor boat
>> you ever heard! Lol Yep! I had grounded both ends of a shielded
>> cable and got a good example of a ground loop!
>>
>>
>> On 11/3/2018 4:54 PM, Mick [email protected] [EVGRAY] wrote:
>>>
>>> Norm,
>>>
>>> Thanks for that.
>>>
>>> I love Mr Calrsons lab, I could happily live there for quite awhile
>>> with all that awesome vintage gear. I have seen isolation
>>> transformers wired like that and it's so insane but I am used to
>>> testing all the grounding points. When building a recording studio
>>> we have to float all the grounds so they are single point at the
>>> service panel and not looped anywhere else. Often they are lifted
>>> at the outlet j-box due to the lack of control in a prewired
>>> building. Ironically we also used to use autoformers for all of the
>>> light dimmers to prevent noise, so we often referred to the variacs
>>> as light dimmers.
>>>
>>> I still don't completely trust a scope on an isolation transformer
>>> even if the ground is properly isolated/ lifted due to the somewhat
>>> rare magnetic emp events we are talking about like when I kicked off
>>> all my ground faults in the house through one.
>>>
>>>
>>> On 11/3/2018 2:03 PM, Norman Wootan [email protected] [EVGRAY] wrote:
>>>>
>>>> Mick! Here is a helpful video regarding scopes and isolation
>>>> transformers on the test bench!
>>>>
>>>> https://www.youtube.com/watch?v=XBsQ3sZ45Fk&feature=youtu.be
>>>>
>>>> https://www.youtube.com/watch?v=xaELqAo4kkQ
>>>>
>>>>
>>>> On 11/3/2018 12:36 PM, Mick [email protected] [EVGRAY] wrote:
>>>>>
>>>>> Norm,
>>>>>
>>>>> Thanks for the nudge in the right direction. Now the process
>>>>> demands repeating with a totally isolated battery source
>>>>> configured the same way. Funny how I was concentrating on
>>>>> isolating and connecting saturated inductive charge without the
>>>>> first magnetic variable taken into account.
>>>>>
>>>>> I have had no problem creating the event with my grid power source
>>>>> and even warned Sven that an isolation transformer will not always
>>>>> protect his scope when messing around with this energy. My scope
>>>>> probe sitting on a bench shot me in the leg when I walked by when
>>>>> performing the experiments from my bench supply. The bench supply
>>>>> has an isolation transformer of sorts. Being it is torroidal there
>>>>> is more inter-winding capacitive coupling and mutual inductance
>>>>> than with the proper EI transformer though there is at least the
>>>>> electrostatic shield and galvanic isolation.
>>>>>
>>>>> Thanks for that reference. the Brit guy was funny, although I'm
>>>>> very familiar with iso transformers in audio work used for
>>>>> galvanic isolation and balancing to eliminate common mode noise.
>>>>>
>>>>>
>>>>> On 11/3/2018 4:42 AM, Norman Wootan [email protected] [EVGRAY] wrote:
>>>>>>
>>>>>> Mick! Your DUH reference is funny! To understand Isolation,
>>>>>> best to study and understand the Isolation Transformer. The
>>>>>> super high quality ones are built to eliminate noise and DC
>>>>>> components that effect sensitive instruments like EEG and EKG
>>>>>> instruments. This will give you an idea as to construction and
>>>>>> purpose::
>>>>>>
>>>>>> https://en.m.wikipedia.org/wiki/Isolation_transformer
>>>>>>
>>>>>> A little tutorial as to how they work!
>>>>>>
>>>>>> https://www.youtube.com/watch?v=sfzy5IQMzyc&feature=youtu.be
>>>>>>
>>>>>> https://www.youtube.com/watch?v=14kPQif9P7c&feature=youtu.be
>>>>>>
>>>>>> https://toroid.com/Products/Medical-Isolation-Transformers
>>>>>>
>>>>>> The 230VAC, 5 HP locked rotor experiment was an example of
>>>>>> electrically isolated electrical circuitry when mains contactor
>>>>>> was opened since there was no neutral involve. There is magnetic
>>>>>> and capacitive coup[ling only The dielectric insulation was not
>>>>>> compromised therefore no electrical connection. The Chinese
>>>>>> motor experiment was isolated, (electrically) when the reversing
>>>>>> action was in transient. (Floating neutral) since there is a line
>>>>>> neutral in the 120VAC input.
>>>>>>
>>>>>>
>>>>>> On 11/2/2018 2:44 PM, Mick [email protected] [EVGRAY] wrote:
>>>>>>>
>>>>>>> Norm,
>>>>>>>
>>>>>>> Since you have performed mass research on this event would you
>>>>>>> concur
>>>>>>> with my long distance observation that the event is not only due to
>>>>>>> charge isolation but inclusive of a magnetic connection from
>>>>>>> source in
>>>>>>> addition to the saturated and lifted inductive load?
>>>>>>>
>>>>>>> Your bell buzzer and bell transformer acting as an isolation
>>>>>>> transformer.
>>>>>>>
>>>>>>> Both motor experiments, the small Emerson type and the HVAC unit
>>>>>>> with
>>>>>>> only two hot's no neutral, must have been powered by an isolation
>>>>>>> transformer of some type also such as the utility step down for the
>>>>>>> neighborhood or dedicated delta or wye for commercial or even
>>>>>>> acted as
>>>>>>> such from the dual windings of the HVAC motor.
>>>>>>>
>>>>>>> Have you reliably produced the NS from any type of isolated battery
>>>>>>> system, or in all such cases was there a magnetic connection to
>>>>>>> an earth
>>>>>>> bonding in another spot?
>>>>>>>
>>>>>>> My thoughts being one side of a transformer acting as a source is
>>>>>>> grounded and the secondary side isolated so that the only
>>>>>>> conceivable
>>>>>>> ground bonding on the sink might be considered as magnetic aside
>>>>>>> from
>>>>>>> the bonded motor frame or what not producing the reconnection.
>>>>>>>
>>>>>>> I may be pissing up a rope notwithstanding the NS seems to be
>>>>>>> predicated
>>>>>>> on a B field connection somewhere in the source feed though the
>>>>>>> neutral
>>>>>>> is isolated electrically.
>>>>>>>
>>>>>>> Perhaps this is a simple "Duh" to you that you had already
>>>>>>> figured out
>>>>>>> assuming everyone else at least this smart. Either way it does
>>>>>>> create
>>>>>>> an interesting position in which to view 3 phase and
>>>>>>> transformers with
>>>>>>> an extra resonant winding.
>>>>>>>
>>>>>>> By the way, ironic your implication that the large medical isolation
>>>>>>> transformers create a heretofore unknown vector of extreme danger.
>>>>>>>
>>>>>>> Mick
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
>