As an experiment and for educational purposes, I wanted to build and connect an FM receiver to some old computer speakers via a 3.5 mm audio jack.
So I tried building a circuit like this on a bread board
Note: The 22pf capacitor on the far left is actually a variable capacitor that I can adjust between 8pf and 40pf. And hopefully, I used falstad correctly to depict my actual circuit.
The circuit on the left consisting of the two transistors is something I found in most FM receiver tutorials. And I figure I couple it to a NPN transistor pre-amplifier circuit on the right. I then connect the output to the tip of a 3.5mm jack.
When I power up the circuit, my speakers are silent. If I touch the antenna with my fingers, my speakers produce a low frequency hum. I disconnected the 3.5 mm jack and hooked up an oscilloscope probe to the output and confirmed there is no signal...in fact I don't even see any noise waveform unless I touch the antenna with my fingers.
Does anyone have suggestions on what I might do next to receive an FM radio signal or at least noise from a blank FM channel?