Arny's ABX device proven defective! [Archive]

Robert Morein

October 10th 05, 04:39 AM

From http://www.electronicstalk.com/news/mat/mat150.html

"A further noise variable that can specifically affect small AC voltages can
be observed with reed contacts and with relays constructed according to the
reed principle - designs with their contact springs in the magnetic field of
the relay coil."
When the contact is closed there is a damped oscillation with a frequency of
between 2 and 3kHz, corresponding to the inherent resonant frequency of the
tongues.

"However a typical level for standard contacts can be extremely significant
on very low-level signal switching circuits."

Once again, Arny and his amphibian sidekick are caught in the quagmire of
unscientific thought and sloppy design.

IN FULL:

----------------------------------------------------------------------------
-----------------------------------------------------
The choice of an electromechanical relay to be included in a low-level
signal circuit can be a crucial factor in determining the levels of
electrical noise within an application.

In basic terms, the electromechanical relay is a comparatively simple
component and when included in an application, it is somewhat governed by
its inherent operating characteristics.

When small DC or AC voltages are switched with electromechanical relays,
noise can be generated, causing possible corruption of the signals to be
switched due to heating and material effects.

Specific constructional techniques during the circuit design, along with a
careful selection of materials by manufacturers, can be employed in order
for such noise generation to be significantly lowered, if not completely
eliminated.

Electrical noise levels occur because of the unavoidability of transition
points between materials along the paths travelled by the signal.

The transition points are always a compromise between the practicalities of
the relay design, compared against an ideal electrical characteristic.

This is due to manufacturing requirements that dictate that the metal
connections are routed into the interior of the relay via sealed or moulded
glass entry points moulded into the metal casing.

To prevent mechanical stress between the glass insulation and the PIN
passing through it when the temperature changes, the coefficients of thermal
expansion of the two materials must be matched.

Unfortunately, this results in the use of contact materials that produce
noise voltages if heated.

The effective temperature differences largely depend on temperature
distribution within the relay and thereby on the relay construction and the
geometry of the connections.

Moreover, the manufacturers' datasheets only very rarely give information on
the thermo electromotive force of relays.

Bret Ludwig

October 10th 05, 05:02 AM

Robert Morein wrote:
> From http://www.electronicstalk.com/news/mat/mat150.html
>
> "A further noise variable that can specifically affect small AC voltages can
> be observed with reed contacts and with relays constructed according to the
> reed principle - designs with their contact springs in the magnetic field of
> the relay coil."
> When the contact is closed there is a damped oscillation with a frequency of
> between 2 and 3kHz, corresponding to the inherent resonant frequency of the
> tongues.
>
> "However a typical level for standard contacts can be extremely significant
> on very low-level signal switching circuits."
>
> Once again, Arny and his amphibian sidekick are caught in the quagmire of
> unscientific thought and sloppy design.

Yeah, but who gives a ****? You aren't going to use his box anyway.

Robert Morein

October 10th 05, 05:10 AM

"Bret Ludwig" > wrote in message
oups.com...
>
> Robert Morein wrote:
> > From http://www.electronicstalk.com/news/mat/mat150.html
> >
> > "A further noise variable that can specifically affect small AC voltages
can
> > be observed with reed contacts and with relays constructed according to
the
> > reed principle - designs with their contact springs in the magnetic
field of
> > the relay coil."
> > When the contact is closed there is a damped oscillation with a
frequency of
> > between 2 and 3kHz, corresponding to the inherent resonant frequency of
the
> > tongues.
> >
> > "However a typical level for standard contacts can be extremely
significant
> > on very low-level signal switching circuits."
> >
> > Once again, Arny and his amphibian sidekick are caught in the quagmire
of
> > unscientific thought and sloppy design.
>
>
> Yeah, but who gives a ****? You aren't going to use his box anyway.
>
Responsibility for this device weighs heavily on those who push it. Arny
should have spent his time synthesizing flu viruses.

ScottW

October 10th 05, 06:28 AM

"Robert Morein" > wrote in message
...
>
> From http://www.electronicstalk.com/news/mat/mat150.html
>
> "A further noise variable that can specifically affect small AC voltages
> can
> be observed with reed contacts and with relays constructed according to
> the
> reed principle - designs with their contact springs in the magnetic field
> of
> the relay coil."
> When the contact is closed there is a damped oscillation with a frequency
> of
> between 2 and 3kHz, corresponding to the inherent resonant frequency of
> the
> tongues.
>
> "However a typical level for standard contacts can be extremely
> significant
> on very low-level signal switching circuits."
>
> Once again, Arny and his amphibian sidekick are caught in the quagmire of
> unscientific thought and sloppy design.
>
> IN FULL:
>
> ----------------------------------------------------------------------------
> -----------------------------------------------------
> The choice of an electromechanical relay to be included in a low-level
> signal circuit can be a crucial factor in determining the levels of
> electrical noise within an application.
>
> In basic terms, the electromechanical relay is a comparatively simple
> component and when included in an application, it is somewhat governed by
> its inherent operating characteristics.
>
> When small DC or AC voltages are switched with electromechanical relays,
> noise can be generated, causing possible corruption of the signals to be
> switched due to heating and material effects.
>
> Specific constructional techniques during the circuit design, along with a
> careful selection of materials by manufacturers, can be employed in order
> for such noise generation to be significantly lowered, if not completely
> eliminated.
>
> Electrical noise levels occur because of the unavoidability of transition
> points between materials along the paths travelled by the signal.
>
> The transition points are always a compromise between the practicalities
> of
> the relay design, compared against an ideal electrical characteristic.
>
> This is due to manufacturing requirements that dictate that the metal
> connections are routed into the interior of the relay via sealed or
> moulded
> glass entry points moulded into the metal casing.
>
> To prevent mechanical stress between the glass insulation and the PIN
> passing through it when the temperature changes, the coefficients of
> thermal
> expansion of the two materials must be matched.
>
> Unfortunately, this results in the use of contact materials that produce
> noise voltages if heated.
>
> The effective temperature differences largely depend on temperature
> distribution within the relay and thereby on the relay construction and
> the
> geometry of the connections.
>
> Moreover, the manufacturers' datasheets only very rarely give information
> on
> the thermo electromotive force of relays.

Robert,
Do you have a clue as to what these guys mean when then mean "small signal"
?

Solar flares probably disrupt their measurements... do you have a problem
with solar flares adversely affecting your hi-fi?

When Middius farts... you may be experiencing power ripple for days.
George...try to contain yourself as Robert is contemplating his hi-fi
performance,
and don't even think about lighting one off again...poor Robert will be
toast. His relays will oscillate indefinitely.

ScottW