Overview
This audio amplifier system does not require a battery power supply, but still gets the energy to produce sound from the AM radio signal.
The power supply comes from the polarized capacitor charged from the antenna. The power supply voltage is only enough to turn on the Transistor.
The energy from the radio signal is amplified by the Transistor, which includes amplifying both the current and the voltage. The voltage amplification is due to the load for the amplified current to pass through, which is the capacitor connected at the output terminal C of the Transistor.
The output signal will be enough for a speaker to produce sound without any external power supply with the amplifier.
Analysis of the circuit diagram and improvements
The electrical oscillation of the AM radio wave received by the Antenna consists of many complex signals, including noise and the official AM signal. The coil L1 and capacitor C5 will exploit this complex power, to supply the polarized capacitor C6 through the bridge diode as shown in the figure.
The capacitor C6 will act as a battery to supply power to Transistor Q1. The voltage is enough to unlock the B-E pin of Q1.
The coil L1 is wound on the Ferrite core to convert the signal with a higher voltage amplitude than when a coil L2 is wound on this Ferrite core.
The signal from L2 will be amplified by Q1, including voltage amplification (because there is a load, capacitor C3). This amplified voltage signal does not go into C6, but goes through C4 to create the output signal. C6 only has the role of supplying power to the transistor Q1.
The output voltage can be up to several tens of Volts, depending on the transformer on the Ferrite core with a large or small L2:L1 ratio.
Capacitor C1 is a variable capacitor, which is used to adjust the resonance frequency with the AM radio signal.
The output can be used immediately, or treated as a small power source. Free energy appears at this output. It can be further converted to get the desired power source.
Improvement:
Consider the output now as the input for the next amplifier system. This amplifier system still does not need any battery to power the transistor, which is the amplifier system above.
This means we use 2 amplifications, with the same method.
At the 2nd amplifier stage, there is no more antenna, instead there is a voltage applied to the primary coil L1, and we get a fairly high L2 when L2:L1 is large.
After this 2nd amplifier stage, we will get a voltage of hundreds of volts and a fairly high current due to the amplification of the transistor.
There is no power supply to the system, but there is still voltage and current at the output when the load there is closed circuit.
Similar technology: A Soviet Audio Amplifier That Generates Energy from the Air
⁂ Self-powered generator with feedback circuit for input.
※ Transistorized snap-off technology to harness energy from dielectric inertia.
※ This is a modern version of the self-powered generator, suitable for today's manufacturing - just buy the electronic components and electrical equipment to assemble, then expand the scale and increase the power of the machine. In addition, the plan has many other modern and unique methods!