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AM transmitter schematic presentation

2016-04-11 07:28  
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This article is the introduction of the principle AM transmitter. The circuit is simple but effective. For you to better grasp the principle, the proposed combination of text to read the schematic. Figure: The microphone  is an electret condenser microphone and volume modulation is based on the 4.7 k is preset resistor P1. This circuit is in two general, audio amplifiers and radio frequency oscillator. This oscillator is based on Q1 and related components. Tank circuit L1 and VC1 is tunable from about 500 kHz to 1600 kHz. These components can be used from an old MW radio, if available. Q1 to regenerative feedback oscillation, which is achieved by connecting the base and collector of Q1 to the ends of the tank circuit. 1 nf capacitor C7, couples signals, based on 100 years, and C2 L1 pf ensure oscillation through the collector, emitter, through the internal resistance of the transistor base-emitter, once again return to base. Resistor R2 has an important role in this circuit. It ensures that the oscillation will be transferred to the ground through a very low internal emitter resistance, reinsurance Q1, also increased the input impedance, so that the modulation signal will not be diverted. VC1 oscillation frequency adjustment. Q2 is wired as a common emitter amplifier, C5 separation emitter resistor and realized that at this stage the total gain. 

 

 

 


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