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2600 Hertz Single Tone Generator  Schematic
-------------------------------------------


Parts:  555 timer I.C.
        8 ohm speaker                          |
        9 volt battery & connector           --+--  =  connection
        Pushbutton switch                      |
        5k potentiometer
        1k ohm resistor                        |
        4.7 micro-farad capacitor            -----  =  no connection
        3.3 micro-farad capacitor              |


                   +----+-------------------------------+
                   |    |                               |
                   |    V      1k                       |
                   |  /\/\/-+-/\/\/-+---------------+   |
          +--------+   5k   |       |               |   |
          |     ---|--------|-------|--------|---   |   |
pshbtn  | o     |  8        7       6        5  |   |   |
switch -+       |                               |   |   |
        | o     |||           5 5 5             |   |   |
          |     |||           TIMER             |   |   |
          |     |                               |   |   |
  (+)-----+     |  1        2       3        4  |   |   |
9 volts         ---|--------|-------|--------|---   |   |
  (-)--------------+        |       |        |      |   |
                   |        +-----------------------+   |
                   |  3.3uF         |        |          |
                   +--->|--------------------+----------+
                   |                |
           4.7uF  \_/               |
                  ---               |
                   |(+)             |
                   |     ______     |
                   +----| 8ohm |----+
                       /__SPKR__\


To calibrate:

Play next to a pure 2600hz source and adjust the 5k potentiometer until the two
sounds are the same. As you get closer you will hear a beat tone form and get
slower and slower. When it stops, the two frequencies are equal. This takes a
little practice.