[ale] Need an Ethernet cutoff relay

[Alex Carver]

That relay isn't suitable for GHz performance however.  RF relays are a
much different form factor than standard SPST (1a) or SPDT (1c) poles.
A regular n-PST or n-PDT has the poles all arranged in parallel planes
like those in the PDF you linked while the armature carrying the moving
contact is connected to the housing pins using braided wire loops or
short sections of stranded wire.  That kind of construction isn't good
for crosstalk, attenuation, or signal balance.

An appropriate module would have to use something like these:
https://omronfs.omron.com/en_US/ecb/products/pdf/en-g6k_2f_rf.pdf

It would be one relay per pair but the DPDT contacts are arranged in a
planar configuration symmetrically around the centerline of the relay
rather than the vertical planes of a standard power relay.  That ensures
minimum crosstalk and also keeps the signals isolated.  The moving
contact is also altered, there's no wire to the housing pin.  Instead
there are four contacts arranged in pairs with a moving bar.  Two of the
contacts are connected together and the other two are the normally open
and closed contacts.  The bar pushes one way to connect a shared contact
wtih the NO contact and then pushes the other way to connect the shared
contact with the NC contact.  No wire loop and precision armatures means
the electrical distance from one pin to another is identical so the
circuits stay balanced.

I'd be making one of these myself but I don't want to spend weeks of
running calculations to get the PC board designed properly for matched
length, matched impedance, and low loss.  If I had PC board software
like Altium it can do those computations on the fly as I draw the traces
and enforce whatever requirements I have on the board design.  I also
don't have $5k to drop on a copy of Altium. :)

On 2021-07-31 09:02, Jim Kinney wrote:
> https://www.morssmitt.com/uploads/files/catalog/products/datasheet-d8-relay-module-v3-2.pdf
> 
> They have a normally open 8 pole relay that can kill everything a cat6 wire can handle. Output the off signal to rpi or arduino with relay hat to drive the higher voltage relays on the wire.
> 
> On July 31, 2021 4:41:29 AM EDT, Alex Carver via Ale <ale at ale.org> wrote:
>> Gah, no X-10.  No remote control either.  This is going to be a
>> hardwired kill-switch application that has to be manually reset.  If
>> the
>> camera gets knocked off the wall, the switch will open and won't close
>> even if they plug the camera back in.
>>
>> On 2021-07-29 09:18, Bob Toxen via Ale wrote:
>>> Great idea.  X-10 remote control could be used to kill power.
>>> X-10 can, of course, be controlled by computer, phone, or otherwise.
>>>
>>> On Thu, Jul 29, 2021 at 10:26:56AM -0400, Phil Turmel via Ale wrote:
>>>> If you can't find anything else, consider a small brainless
>>>> unmanaged POE switch and kill its power.
>>>>
>>>> On 7/26/21 2:18 PM, Alex Carver via Ale wrote:
>>>>> I've been searching for over a week now with no luck.
>>>>>
>>>>> What I'm looking for is a small-ish (DIN rail mount would be ideal)
>>>>> relay device that accepts a signal and will completely cut off all
>> four
>>>>> pairs of an Ethernet connection.   It should at least be shielded
>> (so no
>>>>> cheap switch boxes from Amazon adorned with Brother P-Touch labels,
>>>>> those are also manual push buttons :) ).
>>>>>
>>>>> Some of the closest I've gotten are A/B switches but they're in
>> desktop
>>>>> cases and are just too big.
>>>>>
>>>>> Purpose:
>>>>> I am going to be installing a VoIP door station to replace the
>> doorbell
>>>>> button. It's a PoE unit so I do need all the pairs. It has several
>>>>> additional I/O and power ports for various uses, one of which
>> provides a
>>>>> steady 12 VDC when the unit is up. I plan to link this to a
>> latching
>>>>> relay in such a way that if the 12 VDC suddenly disappears (e.g.
>> someone
>>>>> took a baseball bat and adjusted the camera angle), it will break
>> the
>>>>> Ethernet lines to the exposed patch cable making it a dead cable
>> which a
>>>>> computer can't use.
>>>>>
>>>>> The box itself doesn't need the latching relay, it just needs a
>> simple
>>>>> relay that is either on or off with the application of signal. 
>> I'll
>>>>> take care of the latching part separately with other external
>> relays.
>>>>>
>>>>> I just can't seem to find anything like this.  Just for fun I tried
>> an
>>>>> industrial PoE injector that I had handy which takes 24 VDC in but
>> the
>>>>> data lines are passed right through the unit so even with it off it
>>>>> doesn't stop the drop from working as a minimum 10/100 (two pair)
>> port.
>>>>> _______________________________________________
>>>>> Ale mailing list
>>>>> Ale at ale.org
>>>>> https://mail.ale.org/mailman/listinfo/ale
>>>>> See JOBS, ANNOUNCE and SCHOOLS lists at
>>>>> http://mail.ale.org/mailman/listinfo
>>>>>
>>>>
>>>> _______________________________________________
>>>> Ale mailing list
>>>> Ale at ale.org
>>>> https://mail.ale.org/mailman/listinfo/ale
>>>> See JOBS, ANNOUNCE and SCHOOLS lists at
>>>> http://mail.ale.org/mailman/listinfo
>>> _______________________________________________
>>> Ale mailing list
>>> Ale at ale.org
>>> https://mail.ale.org/mailman/listinfo/ale
>>> See JOBS, ANNOUNCE and SCHOOLS lists at
>>> http://mail.ale.org/mailman/listinfo
>>>
>>
>> _______________________________________________
>> Ale mailing list
>> Ale at ale.org
>> https://mail.ale.org/mailman/listinfo/ale
>> See JOBS, ANNOUNCE and SCHOOLS lists at
>> http://mail.ale.org/mailman/listinfo
>