0
\$\begingroup\$

1st attempt

I have a problem. I built the FM demodulator circuit, but i am not sure if this signal is demodulated. This was my first attempt which following an answer, resulted in a 2nd attempt further down.

enter image description here This is my input - fm modulated signal and output : enter image description here


EDIT - 2nd attempt following advice in an answer:

enter image description here

This is my input - fm modulated signal and output :

enter image description here

Thanks for the help in advance!

\$\endgroup\$
18
  • \$\begingroup\$ Maybe? There isn't really any way to tell anything from those graphs. \$\endgroup\$ – hobbs Jan 17 at 17:47
  • \$\begingroup\$ ahh nope. just looks attenuated \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jan 17 at 17:47
  • \$\begingroup\$ Can't see much difference at that resolution apart from amplitude. Post the schematic of the circuit you're testing \$\endgroup\$ – Neil_UK Jan 17 at 17:49
  • \$\begingroup\$ Ok, I'm adding circuit diagram. \$\endgroup\$ – Chuckyy Jan 17 at 17:52
  • \$\begingroup\$ This is ratio detector, I mean I try build... \$\endgroup\$ – Chuckyy Jan 17 at 17:53
1
\$\begingroup\$

Firstly, you should try and draw schematics so that they can be displayed properly: -

enter image description here

Secondly, you should not use the Rser statement because it hides the important fact that there is 60 Ω in series with the AC source. Well, I say it hides it; I'm not actually sure what it does with LTspice so, better to explicitly show it as a resistor.

And, with Rser at 60 Ω, L = 40 μH and C = 1 nF you get a rather shallow band pass filter effect that, might as well not be present at all: -

enter image description here

Then, the main killer is that you have applied a coupling factor of unity to all the inductors in your transformer, so, it won't work properly. Try something arounf 0.5 instead of 1.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.