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Description:
Ultrasonic
oscillations which are generated by unmodulated ultrasonic transmitters
commonly for remote control are usually affected from other ultrasonic
sources in the media and that's why we are giving a 500Hz modulated
ultrasonic transmitter circuit here.
Voltage supply of the
circuit is 9 Volts and any change of the value will change the
frequency also. You can omit this difference by connecting a resistor
between A and B nodes. You can find the value of the resistor by using
this formula:
R = (Vsupply - 7V) / O.6 Kohm where Vsupply is the new supply voltage value.
The
multivibrator generates 500Hz modulation frequency. To avoid the
frequency differences , tolerance of the circuit should not exceed %5.
If the circuit components changed, then the frequency can be determined by using the formula below,
f = (1.44 x 1000) / (C2 x R3 x C3 x R2)
If C1 and C3 are nanofarads then R2 and R3 will be magaohms.
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