Yep, it is a Slope Detector. The Foster-Seeley Discriminator, the Ratio Detector, the Gated-Beam Detector, and Quadrature Detector, all have a Slope Detector at the hart of their circuits. And of course these circuits greatly improve the frequency response and dynamic range of the signal, over a simple Slope Detector. Thanks!
Yes there is more stereo de-coding circuitry. A good place to get the signal would be the stereo volume control. If you tap the signal at the top of each control, that is just before it is amplified by the audio circuits. If you need volume control of the signal tap the center of each. Your ground lead will be connected to the low side of each, in either case.
@@AllAmericanFiveRadio I've been trying to make an FM discriminator for a year now, and still no success. I was able make an FM pulse counting receiver, and an FM regenerative receiver, and a IC chip receiver, all of which work quite well. But I am still unable to figure out the traditional Foster-Seeley Discriminator or Ratio Detector methods using transformers. I seem to have hit a brick wall, as they say.
Hey Andrew, The audio is developed from the 10.7MHz IF tuned frequency, it is center frequency. The audio causes the 10.7MHz carrier to vary a little above and below the 10.7MHz center IF tuned frequency. This above and below causes the level to decrease in proportion from 10.7MHz center IF frequency. This changing level is the audio information. It is this changing level that is detected. I am looking for a circuit to use. This is my email allamericanfiveradio@yahoo.com
@@AllAmericanFiveRadio I understand the theory. I just haven't had much luck building it. I've tried a few schematics but nothing has actually worked yet.
is this how stereo radios work or is that a different circuit? i saw on another youtuber's video an old tube stereo it has an fm multiplexer and that decodes the coded stereo FM signal and changes that to 2 separate audio signals which head to the amp, ive hacked enough cheap junk radios into ipod amps by hooking onto where the tuner passes the audio signal to the amp, most of these cheap radios didnt come in for nothing anyway, if there is a way to access the amp ill find it
i think i figured it out but i hooked the ground of the audio input from my device to the ground on the volume control and i tapped one of the volume control points and it worked, now i have an amp from an old walkman and i hook power to it and it doesnt power up, oh well ill figure it out
Hello AllAmericanFiveRadio, first of all thank you very much for your interesting, educational and practical videos. I am learning a lot with them. I have a doubt with this, FM Discriminator video. When the left diode conducts I can not see from where the cathode is being polarized negativily. Is it done by means of the capacitor placed inside the FI can? Is very clear in the right diode, because the cathode is grounded. Would you explain me a bit more, please. Kindest regards, José.
+Joseradiola The secondary output is AC audio. That means the polarity at each end changes from positive to negative, then negative to positive. One diode takes care of the positive to negative, the other diode takes care of the negative to positive, like a full wave rectifier for audio.
+AllAmericanFiveRadioThank you for your answer. Yes I understand that, but in 4:48 of the video, I see the anode polarized with positive AC signal but, Who does give the negative polarization to the cathode in order to the diode conduct? That is my doubt. Kindest regards. José
+Joseradiola The cathode of the diode goes through the 100K resistor to one side of the volume control, the other side of the volume control is grounded, completing the circuit.
Thanks.
The youtubers are asking progressively harder questions.
It makes it more interesting and challenging.
Rick
Yep, it is a Slope Detector. The Foster-Seeley Discriminator, the Ratio Detector, the Gated-Beam Detector, and Quadrature Detector, all have a Slope Detector at the hart of their circuits. And of course these circuits greatly improve the frequency response and dynamic range of the signal, over a simple Slope Detector.
Thanks!
Thanks, I have made some new drawings for another video on FM detection, I will get around to making the new video some day.
Brilliantly done! Thank you for sharing!
Thank you, and your welcome.
Yes there is more stereo de-coding circuitry. A good place to get the signal would be the stereo volume control. If you tap the signal at the top of each control, that is just before it is amplified by the audio circuits. If you need volume control of the signal tap the center of each. Your ground lead will be connected to the low side of each, in either case.
AA5,
Great vid on the FM Discriminator circuit!
John S.
...very good explanation..helping me to understand FM better ..........
It is a classic filter. If you Google "Pi Filter" you will get all kinds information. Pi Filters are very useful and are used in countless circuits.
Thanks!
maybe a stupid question, how are the two waves synchronized so that they are in phase?
It’s not synchronized. It is Full Wave Audio Detection. Both side of the audio signal are used.
Could you re-draw this using solid state components?
I'm looking for a solid state circuit. Thanks!
@@AllAmericanFiveRadio I've been trying to make an FM discriminator for a year now, and still no success.
I was able make an FM pulse counting receiver, and an FM regenerative receiver, and a IC chip receiver, all of which work quite well.
But I am still unable to figure out the traditional Foster-Seeley Discriminator or Ratio Detector methods using transformers. I seem to have hit a brick wall, as they say.
Hey Andrew,
The audio is developed from the 10.7MHz IF tuned frequency, it is center frequency. The audio causes the 10.7MHz carrier to vary a little above and below the 10.7MHz center IF tuned frequency. This above and below causes the level to decrease in proportion from 10.7MHz center IF frequency. This changing level is the audio information. It is this changing level that is detected.
I am looking for a circuit to use.
This is my email allamericanfiveradio@yahoo.com
@@AllAmericanFiveRadio I understand the theory. I just haven't had much luck building it. I've tried a few schematics but nothing has actually worked yet.
@@andrewferg8737 Well, I’ll see if I can lower you frustration factor.
is this how stereo radios work or is that a different circuit? i saw on another youtuber's video an old tube stereo it has an fm multiplexer and that decodes the coded stereo FM signal and changes that to 2 separate audio signals which head to the amp, ive hacked enough cheap junk radios into ipod amps by hooking onto where the tuner passes the audio signal to the amp, most of these cheap radios didnt come in for nothing anyway, if there is a way to access the amp ill find it
Good!
Excellent explanation, thank you
Thank you, and your welcome.
I just put it in the UA-cam to do list
Important to choose the right demodulation
Thanks
Thanks YisraelinDiaspora
@AllAmericanFiveRadio could u make a vid about gpu please as they are very difficult to understand the matmatical procedures
Thanks i been wanting to know how a car radio works
i think i figured it out but i hooked the ground of the audio input from my device to the ground on the volume control and i tapped one of the volume control points and it worked, now i have an amp from an old walkman and i hook power to it and it doesnt power up, oh well ill figure it out
@04mittald thank you cant wait for the video
Hello AllAmericanFiveRadio, first of all thank you very much for your interesting, educational and practical videos. I am learning a lot with them. I have a doubt with this, FM Discriminator video. When the left diode conducts I can not see from where the cathode is being polarized negativily. Is it done by means of the capacitor placed inside the FI can? Is very clear in the right diode, because the cathode is grounded. Would you explain me a bit more, please. Kindest regards, José.
+Joseradiola
The secondary output is AC audio. That means the polarity at each end changes from positive to negative, then negative to positive. One diode takes care of the positive to negative, the other diode takes care of the negative to positive, like a full wave rectifier for audio.
+AllAmericanFiveRadioThank you for your answer. Yes I understand that, but in 4:48 of the video, I see the anode polarized with positive AC signal but, Who does give the negative polarization to the cathode in order to the diode conduct? That is my doubt. Kindest regards. José
+Joseradiola
The cathode of the diode goes through the 100K resistor to one side of the volume control, the other side of the volume control is grounded, completing the circuit.
+Hello AllAmericanFiveRadioThat is it. Thank you very much for your answer and help.Kindest regards, José from Chile !!!
+Joseradiola
Your welcome. I'm glad you find my videos useful.
what did you mean by pie filter
man I wish you would talk a little faster
I went into youtube settings and increased the audio speed