Receiver for Jupiter
|RF Amp||Narrow Band Pass Filter||Mixer||Low Pass Filter||Audio Preamp||Audio Power Amp|
Audio Power Amplifier
To amplify the audio signal to sufficient level so that it
can drive the speaker, we have to use the audio power amplifier. The Audio
power amplifier gives two o/p for Audio. One audio o/p drives the headphone
while other is used for recording the data in ‘wav’ format through
the sound card. For this purpose LM386 is selected which can provide voltage
gain of 26dB with the minimum external components. So cost is less.
The i/ps are ground referenced while o/p automatically biases to one-half the supply voltage. The supply voltage is 12V. It can deliver 125mWatts of power of load resistance of 8 ohm.
To introduce the volume control in the receiver, the o/p of the active low pass filter is given to audio power amplifier through a volume control potentiometer as shown in the circuit diagram. To avoid any 50Hz peak up, all the DC power supply lines are bypassed to ground using a 10microF capacitor.