Connecting old telephones...

[Larrchild]

Lets not forget that the Cooper Time Cube is merely one of these with transducers on each end. And look how cool They sound!

1 foot/ms

 

[PRR]

> I need a "Bat-phone" hotline arrangement ... our facility is not averse to "kitschy" ...akin to the red hot-line between the Russian and American... I don't want to bring the "real" phone network system into these rooms.

Ah! Here's all you need, plus a Czech alphabet!

http://www.sportsmansguide.com/cb/cb.asp?a=256367

Czech Military Field Phone Set. Phones have handset and hand-crank. Need D batteries (not included). Check the Czech phone alphabet on top of the phones. Case ...made of tough bakelite material. Set is made by Tesla

 

[Larrchild]

My dad looked at the rooftops of northeast Detroit in 1948 and saw no tv antennae. So his new tv repair shop offered antenna installation. They used those crankup field telephones on every install to aim the antenna, with one guy on the roof and one at the set.

Later as a kid, I used them to play army and call in imagined airstrikes.=)

 

[Guest]

[quote author="PRR"]The nearly-right way, plus signaling, for two phones:

[/quote]
Some modification, which may work:

xvlk

 

[PRR]

> may work:

My very dim memory is that if you put too much current through a carbon mike, the carbon grains are welded together and stop working.

The cold resistance of the lamp is much lower than the hot resistance.

I assumed that if the hot resistance were selected for the proper working current (and sensitivity) in the mikes, the cold-surge would damage the capsules.

Therefore I suggested a fixed resistor and lamps too small to give the mikes trouble.

Also my plan needs 3 wire, I believe your plan needs 4. True, most US telephone cable is 4-wire, and most new studios have plenty of 8-wire ethernet cable. However I think my plan would work in 2-conductor plus shield cable, which studios are full of.

The ex-Military set uses just two wires, using high-voltage low-frequency signaling (ringer)

The signaling could be disabled if there is another signal method, like the loudspeaker intercom that was mentioned. Mine would work that way if the lamps are omitted.

 

[SSLtech]

Been a long time getting back on this one, but I just built another version of this for location recording... Works VERY well indeed.

I used PRR's circuit with a 30V supply (±15V bench supply, ignoring 0 Volts) and the call-alert lights were LEDs with 3.3k ½-Watt resistors in series.

I wired it so that the far-end unit connects through an XLR, and I use a spare line in the multipair snake to run the phone. The light at the far end is mounted in a line termination box with the phone cord socket in it. I labeled the light "Hey, YOU!!!" and it works flawlessly. I'm now able to communicate with the orchestra/choir/band conductor without having to sprint two hundred feet down the corridor from the control room into the chapel.

Best of all, I can plug in any analog phone I want, for kitschy occasions.

Cheap, easy and incredibly useful!!!

Keith

 

[NewYorkDave]

It's a good thing you used PRR's circuit, because whatever the hell it was that I drew seems to have vanished :?
(I guess that's another loss from the twin-x server crash).