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Intercom circuit for 500 type phones

Started by Western Electric, March 26, 2013, 12:15:22 PM

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Western Electric

BELL SYSTEM PROPERTY
         NOT FOR SALE
       Western Electric

dsk

If you still go for 12 V battery  (who should be enough on short lines you need a slightly over the half as voltage of the zener, e.g. 7.5 V 
If you use 24V battery the 15V zener should be fine etc.

The buzzer as described in the article should be of lo current consuming type, and will be about the rest of voltage when you take e.g. 12 battery - 7.5 Zener = 4.5V buzzer. (a 5 or 6V will probably work fine) Actually a the electronics from a playing gratings card will do.  ;D  All this values are approximately, but if the total voltage of the zener's are less than the real voltage of your power-supply, it will always use power. 

dsk

Western Electric

Should I use
A.12v buzzers with 12v zeners
B. 6v buzzers with 12v zeners
C. 12v buzzers with 5.1v zeners
D. 6v buzzers with 5.1v zeners
E. none of the above
BELL SYSTEM PROPERTY
         NOT FOR SALE
       Western Electric

dsk

 ;)E

Assuming you still have 12V power, my suggestion will be 7.5V zener, and approx 5V low current beper.
If you double the voltage, double all the other values too.

dsk