The red box generates three sets of tones to simulate currency.  ALL redbox 
tones are a combination (DTMF) of 1700 + 2200.  A nickel is a 60 ms tone.  A 
dime is 2 60 ms tones, separated by a 60 ms pause.  Finally, the quarter is a 
COMBINATION of 5 35 ms tones, each one separated by a 35 ms pause.

Each time the pushbutton is pressed, it triggers half of IC1,
configured as a monostable multivibrator to energize the rest of the circuit 
for a length of time determined by the setting of the coin selector switch.  
This in turn starts the other half of IC1, configured as an astable 
multivibrator, pulsing on and off at regular intervals at a rate determined 
by the 50k pot between pins 12 and 13.  The output of the astable thus 
alternately powers of IC2, configured as a square wave oscillator, providing 
the required 1700hz and 2200hz to the op amp which acts as a buffer to drive 
the speaker.

   For alignment, a frequency counter and triggered sweep oscilloscope are 
extremely handy (but not absolutely necessary.)

   Install a temporary jumper from +9v supply to pin 14 of IC2 and 
temporarily disconnect the 0.01uF capacitors from pins 5 and 9 of IC2. Power 
up the circuit.  Measuring the output from pin 5 of IC2 with the frequency 
counter, adjust the 20k pot between pins 1 and 6 for an output of 1700hz.  
Now adjust the 20k pot between pins 8 and 13 for an output of 2200hz from pin 
9 of IC2.  Remove the temporary jumper and re-attach the capacitors to pins 5 
and 9.  (Note: if no frequency counter is available, the outputs can be 
adjusted by ear one at a time by zero-beating the output tone with a computer 
generated tone of known precision.)

   Next, temporarily disconnect the wire between pins 5 and 10 of IC1. Set 
coin selector switch in the "N" (nickel) position.  With the oscilloscope 
measuring the output from pin 9 of IC1, adjust the 50k pot between pins 12 
and 13 of IC1 for output pulses of 60 millisecond duration.  Reconnect the 
wire between pins 5 and 10.  (Note: If no scope is available, adjust the 
pulse rate by ear using computer generated tones for comparison.)

The remaining adjustments are made by ear.

   Leave the selector switch in the "N" position.  Adjust the 50k pot 
labelled "Dime" for a quick double beep each time the pushbutton is pressed.

   Finally, set the selector to "Quarter".  Adjust the 50k pot labelled 
"Quarter" until exactly 5 very quick beeps are heard for each button press.  
Don't worry if the quarter beeps sound shorter and faster than the nickel and 
dime ones.  They should be.

   If all went well to this point, your red box should be completely aligned 
and functional.  A final test should now be conducted from a payphone using 
the DATL (dial access test line) coin test.  Dial 09591230 and follow the 
computer instructions using the red box at the proper prompts.  The computer 
should correctly identify all coins "simulated" and flag any anomalies.  With 
a little discretion, your red box should bring you many years of use.  
Remember, there's no such thing as spare change.!

Parts list for Red Box

Semiconductors
--------------

(2)556 dual timer
(1)741 Op Amp
(1)1N914 Switching Diode

Resistors
---------

(6)10k           (1)4.7k
(2)100k
(4)50k PC Mount Potentiometer
(2)20k Multi-Turn Potentiometer

Capacitors
----------

(10)0.01uF        (1)1.0uF
(2)10.0uF Electrolytic

Miscellaneous
-------------

(2)14 Pin Dip Socket
(1)8 Pin Dip Socket
(1)3-position Rotary Switch
(1)Momentary Push-Button Switch(normally open)
(1)SPST Toggle Switch
(1)Speaker or Telephone Earpiece Circuit Board
(1) Box
(1) 9v Battery Clip
Mounting Hardware


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            ³      ³  ³   ³    C6                                     ³
            ³      ³  ³   ³     ³                                     ³
            ³      g  g   g     g                                     ³
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              R11    ³      R12   ÚÄÄÄ¿                               ³
         ÚÄÄ¿  ³     ³       ³    ³   v                               ³
         v  ³  ³  ÚÄÄÅÄÄ¿    ÃÄÄÄÄÁÄÄR13ÄÄ¿                           ³
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    ³        ³                   8ÃÄÄÂÄÄÄÄ´                           ³
    ÃÄÄÄÄÄÄÂÄ´6                   ³  ³   C12                          ³
    ³      ³ ³                  12ÃÄÄÙ    ³                           ³
    ³      ÀÄ´2    IC2 556        ³       ³                           ³
   C7        ³                    ³       g                           ³
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    ³     ³  ³    7   5   9       ³     ³                             ³
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          ³       ³  C9  C10            ³                             ³
          ³       ³   ³   ³             g                             ³
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                  g     ³                                             ³
                        ³            ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
                        ³            ³                 ³
                        ³           R14                ³
                        ³            ³           ³\    ³
                        ³            ³           ³  \  ³
                        ÃÄÄÄÄÄÄÄÄÄÄÄÄÅÄÄÄÄÄÄÄÄÄÄÄ³3   \³
                        ³            ³           ³    7 \
                       C13          R15          ³IC3     \
                        ³            ³           ³741    6/ÄÄÄÄÄÄ¿
                        ³            ³           ³    4 /        ³
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                                                                 ³
                                                                 g
Schematic part variables list.

Resistors
---------
R1 - 10k   R2 - 10k   R3 -4.7k    R4 - 10k   R5 - 10k   R6 - 50k
R7 - 50k   R8 - 50k   R9 - 50k    R10- 20k   R11- 10k   R12- 10k
R13- 20k   R14-100k   R15-100k

Capacitors
----------
C1 - 0.01uf   C2 - 1N914 switching Diode   C3 - 1.0uf   C4 - 0.01uf
C5 - 0.01uf   C6 - 10uf   C7 - 0.01uf   C8 - 0.01uf   C9 - 0.01uf
C10 - 0.01uf   C11 - 0.01uf   C12 - 0.01uf   C13 - 0.01uf   C14 - 10uf

Switches
--------
S1 - SPST toggle
S2 - Momentary push button N.O. labeled "Deposit"
S3 - 3-position rotary switch

Miscellaneous
-------------
g - Ground
@q - Label "quarter"
@d - Label "dime"
@n - Label "NICKEL"
