This is a relatively new box, and all it basically does
is serve as a phone ringer. You have two choices for
ringers, a piezoelectric transducer (ringer), or a standard
8 ohm speaker. The speaker has a more pleasant tone to it,
but either will do fine. This circuit can also be used in
conjunction with a rust box to control an external something
or other when the phone rings. Just connect the 8 ohm
speaker output to the inputs on the rust box, and control
the pot to tune it to light the light (which can be replaced
by a relay for external controlling) when the phone rings.
__ /|
FROM PIN 2 < - -- --- ---------|(---------. .-------| |/ |
>||< |S1| |
>||< --| | |
>||< | |__|\ |
G<---------.>||<.--- \|
T1
c. Elctro magnetic transducer
Parts List
----------
U1 - Texas Instruments TCM1506
T1 - 4000:8 ohm audio transfomer
S1 - 8 ohm speaker
R1 - 2.2k resistor
R2 - External variable resistor; adjusts timing frequency
C1 - .47uF capacitor
C2 - .1uF capacitor
C3 - 10uF capacitor
L1 - Tip
L2 - Ring
L1 and L2 are the phone line.
Shift Rate:
-----------
This is the formula for determining the shift rate:
1 1
SR = --------------------- = ------------ = 6.25 Hz
(DSR(1/f1)+DSR(1/f2)) 128 128
---- + ----
B ( 1714 1500
DSR = Shift Devider Rate ratio = 128
I f1 = High Output Frequency = 1714
B_cD02 = Low Output Frequency = 1500
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