LM386 production amplitude radio ----- LM386 AM RADIO

The modulation radio filled with two audio integrated blocks LM386N has a large volume output. The drawings are the circuit diagrams of the radio, L1 and C1 constitute a resonant circuit, and the received tiny voltage is sent to IC1, D1, R3, and C6 are connected to the IC1 output. Used as demodulation of high frequency amplitude modulation signals. High frequency components pass by C6. No need to use a low-voltage detection diode (such as a tube), the signal amplified by the LM386 is sufficient to overcome the 0.7V voltage drop of ordinary silicon diodes. The end-level LM386 implements audio amplification, output sufficient power to drive small speakers, and the potentiometer P1 controls the volume. In order to increase the stability of two integrated blocks. Its output termination RC network (R1 and C3, R4 and C9), 47 μF capacitance (C2, and C8) are connected to the bypass end of each integrated block to suppress the odd harmonics of the power supply voltage. When the battery capacity drops, it can maintain normal operation when the internal resistance increases. L1 in the tuning circuit can be 10mm in diameter, 37 mm of ferrite magnetic rod, with a φ0.3mm enameled wire, with an inductance of 390μH; or φ0.4 mm enameled wire in diameter 12 mm, length 190 mm iron oxygen The magnetic rod wound around 80 turns, its inductance is 550 μH. Note that the first stage is the high frequency circuit, the IC1 and the components around it should be as close as possible, and even the method of metal shield isolation high frequency and low frequency areas. If you don't add antenna. Not grounded. The radio is not as good. A few meters of copper wire hanging on the ceiling can be an antenna, which is connected to the water pipe is a good grounding method. for safety. Do not use the ground wire in the AC power outlet. The battery voltage is 9V to 12V, and the current consumes 10 mA when using a 9V battery.

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