The aim of the exercise is to design a ratio detector FM demodulator circuit. enter image description here

UPDATE: I changed the circuit: enter image description here

This is my transient analysis in output: enter image description here

I found the information about AC analysis and it would look like it: enter image description here

But my result of AC analysis: enter image description here

Is it good? It seems okay to me, but I cannot explain why.

  • 3
    \$\begingroup\$ There's a vague resemblance but that circuit looks wrong in a number of ways. Normally (my experience) the transformer is center-tapped on both primary and secondary and there's a capacitor that ties the center-taps together. That's missing above. The output is taken from the midpoint of the two caps after the diodes. You just ground it. There's an AGC output taken from your C1 to feed back to the earlier limiter stage. Nothing like that in your diagram. A missing resistor from mod output to secondary center-tap, etc. Why don't you explain your design? It may help a lot in helping you. \$\endgroup\$ – jonk Dec 31 '20 at 1:45
  • \$\begingroup\$ I took note of your comment and edited the schematic. What do you think? I got information from Wikipedia and a thread on the forum. \$\endgroup\$ – Chuckyy Dec 31 '20 at 11:34
  • \$\begingroup\$ Your parts are as far apart as are the streets in my neighborhood. I agree that your schematic is very different to the ratio detector circuits shown in google. \$\endgroup\$ – Audioguru Jan 12 at 20:11
  • \$\begingroup\$ @Audioguru, so what I should improve? Maybe coils are wrong? Previously, I had a capacitor connecting these coils, but in another forum they advised me to remove this capacitor. \$\endgroup\$ – Chuckyy Jan 12 at 20:40
  • \$\begingroup\$ (Notation for transformers in LTSpice.) \$\endgroup\$ – Peter Mortensen Jan 13 at 7:10

Your Answer

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

Browse other questions tagged or ask your own question.