Voltage indicators???

[Perion]

Everyone has seen or maybe used those inexpensive AC voltage indicators that
beep or light a neon lamp when help close to an ungrounded "hot" conductor. I'm
wondering - do they just sense the varying electric field around the conductor?
Since they don't require any current flow in the conductor they're can't be
using any magnetic field component.

Perion

 

[Charles Perry]

Everyone has seen or maybe used those inexpensive AC voltage indicators
that
beep or light a neon lamp when help close to an ungrounded "hot"
conductor. I'm
wondering - do they just sense the varying electric field around the
conductor?
Since they don't require any current flow in the conductor they're can't
be
using any magnetic field component.

Perion

Yes, most of them detect the electric field. I say "most" because it would
not surprise me if there is a product that does it differently, but I only
know of products that use the electric field.

Charles Perry P.E.

 

[Charles Perry]

| Everyone has seen or maybe used those inexpensive AC voltage indicators
that
| beep or light a neon lamp when help close to an ungrounded "hot"
conductor. I'm
| wondering - do they just sense the varying electric field around the
conductor?
| Since they don't require any current flow in the conductor they're can't
be
| using any magnetic field component.

Are you touching the metal part of that indicator when you operate it?
I think that is part of the key. It could be sensing static voltages
being drawn off through it to your body.

The ones I have seen are all plastic. No metal to touch (good thing too
since you are using it near energized conductors).

Charles Perry P.E.

 

[Charles Perry]

On Wed, 13 Oct 2004 08:06:24 -0400 Charles Perry

| Yes, most of them detect the electric field. I say "most" because it
would
| not surprise me if there is a product that does it differently, but I
only
| know of products that use the electric field.

Got any schematics so I don't have to destroy one? My big curiosity is
if it sees the AC as 60 Hz or 120 Hz. If I built two detectors like it
and fed the rectified signal via an LED, with each on oppose sides of a
120/240 circuit, would the LEDs alternate "railroad crossing style" at
60 Hz or would they just blink in unison at 120 Hz?

No. I don't have any schematics. I would imagine finding one wouldn't be
impossible. I don't think they care about frequency. The ones I have used
have a battery and thus the LED lights via DC current, not induced AC from
the field.

Charles Perry P.E.

 

[Charles Perry]

On Wed, 13 Oct 2004 20:06:58 -0400 Charles Perry
|
| |> On Wed, 13 Oct 2004 08:06:24 -0400 Charles Perry
|>
|> | Yes, most of them detect the electric field. I say "most" because it
|> would
|> | not surprise me if there is a product that does it differently, but I
|> only
|> | know of products that use the electric field.
|>
|> Got any schematics so I don't have to destroy one? My big curiosity is
|> if it sees the AC as 60 Hz or 120 Hz. If I built two detectors like it
|> and fed the rectified signal via an LED, with each on oppose sides of a
|> 120/240 circuit, would the LEDs alternate "railroad crossing style" at
|> 60 Hz or would they just blink in unison at 120 Hz?
|>
| No. I don't have any schematics. I would imagine finding one wouldn't
be
| impossible. I don't think they care about frequency. The ones I have
used
| have a battery and thus the LED lights via DC current, not induced AC
from
| the field.

It's not the frequency I care about. What I want to do is set up 2 of
them
on 2 hot wires, one fed by a red LED and one fed by a green LED, and have
a
3rd device receiving those LED blinks determining if the wires represent
opposite or same phase. Or maybe even phase angle.

I understand what you want, but there are no "blinks" with the normal
devices. The LED goes full on via a DC voltage when an electric field of
the correct parameters is detected.

You need to keep in mind that what you would be "detecting" would be an
e-field that was the sum of the sources. I doubt you could distinguish one
line from the other if both were energized.

Charles Perry P.E.