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#127249 05/13/01 06:49 PM
Joined: Oct 2000
Posts: 5,392
S
sparky Offline OP
Member
Ok, bear with me here as this Q may really not be worthy of the theory area.
[Linked Image]

Some time ago i was apprenticed to an individual who liked to use those little two wire testers,( before volt-tics) the ones with the small lighted end that are $1.19 at any hardware store.

The proper way to use these is to touch each lead to what is being tested, however, we used these to determine the hot wires by holding one lead, touching hots with the other.

The result being a dimmer lit tester on contact with the hot conductor.

so did the 'circuit' have to be completed, or was the tester lit by other means???

[Linked Image]

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#127250 05/14/01 12:28 AM
Joined: Nov 2000
Posts: 2,236
Likes: 1
Member
I came across a screwdriver looking thing with a small bulb in it. A metal cap on the end of the handle was for the sparky to touch while testing hots similar to a volt tic , but actually touching a hot, metal part; like the one you describe, the light would burn with a faint, yellow glow with voltage present. Unlike the tester Steve mentioned, this device was designed to be used this way.

A circuit using your body as the return path? Got me...

[Linked Image]


[This message has been edited by sparky66wv (edited 05-14-2001).]


-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI
#127251 05/14/01 02:20 PM
A
Anonymous
Unregistered
For such a tiny little tester, I think that the capacitance and very modest dissipation of a human body is all that is needed to complete the circuit.

I recently purchased a piezoelectric grill lighter. I was slightly amused to find that it will arc to almost any substantial conductor even though there is clearly no low impedance return path.

#127252 05/14/01 02:59 PM
Joined: Nov 2000
Posts: 2,236
Likes: 1
Member
Dspark,
(I promise not to flame you here, this is out of my league!)

If the body is acting as a capacitor, would the light eventually stop glowing when we've reached our charged capacity? Then should we be careful about discharging ourselves? Is dissapation is the main factor preventing this from being the case?

I'm asking here, and I don't fully understand capacitance, so be easy on me!


[This message has been edited by sparky66wv (edited 05-14-2001).]


-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI
#127253 05/14/01 04:43 PM
A
Anonymous
Unregistered
Quote
(I promise not to flame you here, this is out of my league!)

Okay. (I didn't see where you conceded that 180 degrees out of phase is correct.)

But If I'm wrong, flame away. It's more likely that I'll remember.

Quote
If the body is acting as a capacitor, would the light eventually stop glowing when we've reached our charged capacity?
No. Since it is AC, I would venture that we are also discharging at a roughly equal rate.

And charge dissipates slowly no matter how insulated we may try to be. If you get too charged, the ions will leave on your breath.


I think the following is a "complete" circuit:

{60 Hz AC ungrounded conductor} +++ {LED} +++ {moderate value capacitor} +++ {no connection, i.e., air}

A human body serves as a moderate capacitor.

Quote
Then should we be careful about discharging ourselves?
No. In no case that I can imagine would a dangerously large charge collect from household voltages.

Quote
Is dissapation is the main factor preventing this from being the case?
I think the alternating current is the main reason.


Quote
I'm asking here, and I don't fully understand capacitance, so be easy on me!
I don't understand it either. That's why I'm not fully answering. Like I said, I was somewhat amused by the apparently open circuit piezoelectric spark.

Electric cattle fences will also light up neon bulbs "open circuit".

#127254 05/21/01 07:42 PM
Joined: May 2001
Posts: 5
R
Junior Member
Cheaper indicators , biult off-shore, use a 75V gas discharge tube which can give a visible indication at quite low current. Units employing Led's often have to pulse the part using a diac-like device discharging a fair sized capacitor (10nF) when it hits ~32V, to get visibility.

#127255 05/21/01 08:41 PM
A
Anonymous
Unregistered
>a fair sized capacitor (10nF)
Any idea of the capacitance per pound of living human body?


[This message has been edited by Dspark (edited 05-23-2001).]


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