Shortwave radio receiver circuit
A very simple shortwave radio receiver circuit can be designed using circuit diagram bellow.
This shortwave radio receiver circuit is based on 2N2222 transistors and has and has an operating frequency range between 6 and 17 Mhz .
All coils are designed using an inch diameter pvc pipe and 20 gauge insulated hookup wire, L1 require 6 turns and L2 require 14 turns.
You can add turns to or subtract turns from L(or change C2) to receive other frequencies.
R1 and R2 provide a large amount of negative bias at the emitter of Q1 to achieve smooth control.
Q2 and Q3 form an amplifier, which has sufficient output level to directly drive headphones or a small speaker, amplify the detected audio signal output from D1. R3 can replaced with a 2k ohms potentiometer , if you want to use it as an volume control .
R4 and C4 form a lowpass filter that maintains circuit stability and improves the receiver's sound quality. D2, D3, and D4 implement a low-cost voltage regulator to keep the voltage supplying Q1 fairly constant, which minimizes drift.