Frequency detector

jpanhalt said:

Hi ariakovo,

I understand how datasheets can be confusing, because other applications than the one you want may also be presented. In the case of the 567, go to its page 8.
You will see a circuit called AC test circuit and application information on the right side that gives the formula for calculating the frequency you need. In this case, it is:
1/(1.1*R1*C1)

I have attached a part of a schematic from a circuit I built with actual values. I don't recall at the moment what its frequency was. On that circuit, the components to adjust the frequency are labeled C4, R7, and R8. That is, the RC filter attached to pins CT and RT. YOu will need to calculate appropriate values for the frequency you decide to use. Good luck. John

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jpanhalt said:

It will respond only to the frequency to which it is tuned (don't forget it has a finite bandwidth). A sufficiently different frequency will not cause a change in its output state. In fact, its name "tone decoder" described that function. A series of 567s tuned to the different telephone tone frequencies could tell you which keys had been pressed. John

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