How to break this circuit apart?

[Valentins]

I'm trying to build this circuit,when I was simulating the circuit I was getting different results from my source. Guys I need help on breaking this circuit apart to understand how circuits operates.
This is my source
How to build AM Receiver (circuit diagram)
This is my circuit
**broken link removed**

 

[crutschow]

How exactly are you simulating this? What is different from the source?

The circuit has regenerative feedback so it likely is difficult to properly simulate. Are you simulating the circuit with AC analysis or the Transient analysis?

 

[RCinFLA]

There is no regenerative AC feedback. The first two stages are similar to a darlington pair with 330 ohm collector load with a 120k DC feedback to first transistor's base. The collector voltage of second stage should be about 1.5 vdc, yielding about 22 mA's for second device collector current. This does not look like a very good AM detector. It works by fact that second stage collector is close to saturation. AM radio tank circuit is L-C in front. Tuning is about 400 pF at 560 kHz to 50 pF at 1600 kHz.

Third transistor is just an audio amplifier. DC bias feedback is provided by 560k.

If you want to simulate circuit, inject an AM modulated AC source from 560 kHz to 1600 kHz through a 1 pF cap tied to base of first transistor. It will peak at the L-C resonance point. You can modify the 500 pF through the 400pF to 50 pF tuning range. Set first to 400 pF and should peak close to 560 kHz. Raise your AC source level to get a large enough output.

The 200 uH coil is meant to be a 'ferrite loop stick' to provide enough RF pickup. A regular 200 uH coil will not work unless it is wound on a large air form. You can tie a wire through a capacitor to the base of first stage as an extra antenna to improve reception but be aware the wire will add some stray capacitance which will effect the resonant frequency of L-C tank, require retuning of variable capacitor.