PC radios are certainly nothing unusual. However, unless you are prepared to spend a lot of cash you can’t buy a wideband PC radio that receives short-wave signals — if you want one that will not break the bank, you will have to build it yourself. There’s no need for a battery or power supply, since power can be drawn directly from the PC serial interface. The audio signal is fed into the PC sound card. The circuit diagram in Figure 1 shows this simple audion receiver. The transistor in the common-emitter circuit demodulates AM signals, thanks to its exponential characteristic curve.
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