94. FM Ratio Detectors
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- čas přidán 2. 08. 2024
- Here's my take on the ration detector in the Elenco radio. Theory and testing as always. I didn't mention it in the video but I've only seen a ratio detector like this once in an old tube radio - in a book, no practical experience with it.
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Hola: Fantástica tu explicación acerca del ELENCO, aunque a veces es difícil de entender el inglés. También van mis felicitaciones por el extraordinario Laboratorio que posees. Desde Medellín, Colombia, te saluda, Ignacio Escobar Mejía.
Excellent series!! I’ve been watching each of these video as I’m about to build the same kit. Thank you for providing thorough and understandable explanations. You knowledge is a tremendous!👏👏👍👍😃
Awesome, thank you! I try to make the topic approachable. Appreciate you taking time to watch my videos.
Thank you very much. This is the best explanation on FM Ratio Detectors I have found so far anywhere ! I will probably be purchasing the Elenco AM/FM Radio kit to boost my learning.
Glad it was helpful!
Dear Sir, I am currently building this radio, I have completed the am section and now I turn to the fm section, i am a studying the radio circuits and this video is the best I have ever viewed. Thank you kindly for sharing your knowledge of this circuit with us... GREAT JOB... HAVE A GREAT DAY...
Best of luck in your build. Glad it helped and thanks for watching.
Thank you for your effort. It really helped me ♥️
You're welcome 😊
Two things,
Would you provide link to radio?
And I really hate the CZcams algorithm. You should absolutely have much more traffic coming your way. I've watched you for years off and on (mostly to fill in book study gaps for discreet transistor circuit issues). Your explanation are ALWAYS exactly what I need. In short, thanks
Thank you Michael. The channel has grown more than I expected to ne honest. If I could get a really professional into, a hand model, and more cats in the videos, I would have more subscribers!
Great video on the ratio detector!! Two questions: How can you tell from the schematic that the detector is only rectifying the negative half of the IF? Also, the phasor diagrams make sense, but I find it hard to visualize the current paths through the diodes below and above resonance. Can you use your schematic to show current direction? That would be a great help to me! Thanks for doing this series. I built this radio and I want to better understand the FM demodulator in more depth.
I am building this Elenco Radio and I am at the stage of building the FM Ratio Detector. Your explanation is fantastic and easy to understand. I have also found that the stand for the radio is not the most stable. Are you able to share the STL file that you used to upgrade the stand on your 3D printer. Thanks for a well done explanation.
Hi Peter. sadly I erased the STL, otherwise I would be more than willing to share it. Thanks for watching my videos!
I am stumped at this stage. I can theoretically calculate AC gain, but cannot measure the small number with my oscope. I also cannot set T4 and T5 because I can't see a clear enough signal on my oscope. I'm using a Sigilent SDS1202X-e scope and a Sigilent SDG1032x generator. Any advice? I am new to the equipment so I may not have it set up correctly.
Is tuning T4 and T5 by ear (the tone) for maximum volume an acceptable method?
Are they really using germanium diodes in the detector? I thought those things were difficult to obtain nowadays. I would have expected them to substitute something else like a schottky that is available in modern manufacturing processes.
Yep, they are germanium diodes. I recall them being hard to get for a while - I couldn't find one for a crystal radio I was messing with a few years back. Seems like the average price now is about 20 cents. I don't think any are made in the U.S. any more. You could also use a 1N270..
Thanks for nice video ! Could you let me know how and where I can buy FM ration detector appeared in this video ?
You could buy the parts independently. Just be sure to purchase the correct transformers so you will need one with a green top and another with a pink one. As long as the colors are correct, they should be useable (the colors identify the function or functional area they work in). Thanks for watching!
Dear Sir, I have a question, I will be using the Eico 324 signal generator and a Eico 377 audio generator, I have aa duel trace scope, is the all I need for the aignment? Thank you kindly for any feed back..
Yes it will do a lot of the work. Of course, a DMM is a must for the bias measurements. Enjoy building the radio!
thanks for the video, but I felt like there was to much going on and not fully described. I'm still quite puzzled as to how FM demodulation works. Perhaps it would be better if you started by giving an overview of what the circuit did (like with block diagrams) and then start to add the component by component for each respective stage of the demodulation and explained why they are there.
For example, for the Fm discriminator, it was not clear as to why the two inductors would give a positive voltage for high frequacies and a negative one for lower frequencies.
Sorry for the delay in responding. This circuit, like a few others, depends on material learned in an AC circuits course. Describing why phase relationships change in this circuit would have taken a lot of time. I do intend to cover this in future videos. Thanks for watching!
Just one point,the circuit does’nt show exactly where the 9volts comes in?
When you did the transistor biasing you took into account a voltage drop across the 200 ohm resistor,this only feeds to the demodulator diodes,I presume the 9 volts comes in from the top left therefore the 200 ohm resistor doesn’t come into the biasing equation ??
Of course this depends on where the 9 volts is coming in?...ie V+ or V+?..labelled the same🙀
Interesting circuit this ratio detector, Usable for small band FM signals as well?
Yes, it can be used for the lower bands. As long as the IF doesn't exceed the rated diode maximum frequency you should be okay.
I'm convinced that the variable tuning capacitor in my kit doesn't work. Do you know the specs on this part so I can replace it?
Hi Gregory, I think you can get one from this link www.aliexpress.com/i/32797959258.html Seem pretty expensive but it can help you look for other parts that are similar now that you have a starting point.
Sir, I've recently found your channel and am impressed by your knowledge & explanations but have been highly frustrated by your hand obstructing that which you are annotating.
Perhaps you could use a slim pointer in order to avoid obstruction to the viewer.
Noted. I'll keep an eye out for that. Thanks for watching.
I think your contrast/saturation may have been turned a little high
That happens occasionally but I have medicine for that now. I'll keep a better watch on that next go around and thanks for the feedback.