I’m fairly new to electronics / electrical engineering, and I’ve been reading about amplitude modulation because I find it really intriguing.

I found the following AM modulator circuit online and tried it out (Carrier is V2, Message Signal is V1). It works great in practice, but I don’t really understand how it works or why it’s capable of modulating the signal.

In particular, I’m confused about:

• How this circuit actually modulates the carrier with the input (message) signal
• Which part of the circuit causes the carrier amplitude to vary
• Why the peak-to-peak of the modulated signal is 1.25V instead of the messages 2.5V

I have a rough theoretical understanding that AM means changing the amplitude of a high-frequency carrier according to a lower-frequency signal, but I can’t quite connect that idea to what’s happening inside this circuit.

A simple, step-by-step explanation of the signal flow would be really helpful. Time-domain intuition would be especially appreciated, since I’m still learning how to think about these circuits.

Thanks a lot, I’m enjoying learning this stuff and would love to understand it more deeply instead of just knowing that it “works.”