Using Phase-Shift type RC Oscillator theory iam trying to design a circuit which can generate DIAL TONE type of sound just like we hear in our normal telephone sets when it goes off-hook.
I have used KA1458 which is a dual op amps. I have used one op amp as RC oscillator and the 2nd one as buufer and supplied this op amp with -ve 5 volts and +5 Volts. Assuming the capacitor as 0.1uf i have worked the ressitor value using
Freuqency = 1/ 2*pi*R*C*under-root6. placing the frequency as 450 Hz.
The Dial tone which iam getting is not perfectly like the Dial tone which appears in normal telephone sets connected with PSTN. Is tehre any other way of generating Dial tone or suggest any adjustment in this schematic. Iam looking for the most economical solution.
I have used KA1458 which is a dual op amps. I have used one op amp as RC oscillator and the 2nd one as buufer and supplied this op amp with -ve 5 volts and +5 Volts. Assuming the capacitor as 0.1uf i have worked the ressitor value using
Freuqency = 1/ 2*pi*R*C*under-root6. placing the frequency as 450 Hz.
The Dial tone which iam getting is not perfectly like the Dial tone which appears in normal telephone sets connected with PSTN. Is tehre any other way of generating Dial tone or suggest any adjustment in this schematic. Iam looking for the most economical solution.