![]() The secondary characteristics do not appear on any schematic but the designer was aware of them when those components were selected, and it influenced how they put the radio together. They all have secondary characteristics that impact how they perform in circuits. A schematic merely tells you how physical parts are connected together. To second what Acornvalve has already said, you would be a lot better off doing something like this from a kit, rather than trying to go it alone. Looking at the plethora of kits for an FM radios on ebay, including all the ones with digital tuning that I least prefer, I only ever saw one recently that caught my eye that I would expect would work properly because it follows the same sort of design and componentry for a radio that does work properly with a good assortment of the appropriate RF and IF transformers, a good grounded base input amplifier, a proper IF, ratio detector and on top of that a sensible audio amplifier: ![]() In addition they appear to have more distortion in the audio.Ī conventional design with transistors and many coils and a proper ratio detector appears to give the better results. The IC radios tend to have poorer sensitivity, more noise and difficult tuning and don't tune smoothly across the station (when they have analog tuning control). ![]() Some generalizations perhaps: Nearly always I have found the FM radio's based on IC's are "hopeless" compared to what was a standard FM radio of the late 1960's or 1970's era. Some being simple with a few transistors, others use FM radio IC's, such as the Philips TDA7000 or similar number and an LM386 for the audio. Over the years a number of FM radio kits have appeared on ebay. Last edited by Dare4444 on Mar 8:31 am, edited 5 times in total. TEA5767 datasheet says that it's very sensitive but during testing its sensitivity was average. If you are familiar with PCB design software then the coil could be etched on the board itself. You won't have to retune again and again. Heating the coil with my warm fingers only shifted the frequency by < 3KHz. The benefit I got was very low frequency drift at 95MHz. After drying up for a day it was ready to use. I let it dry for 1 hour and then applied one more layer and carefully tilted it up/down/right/left for an even spread. Then I applied another layer on top of the coil and moved the coil so that it evenly spread all over the coil. After winding 12T I held the tension in place or kept pulling at the coil tightly for 5 mins until it dried up. I think it's made out of fibers like in paper. Yet an advanced builder.) I don't have an O-scope, but I did obtain a Capacitance/Inductanceġ53nH when I made it was 12T 25AWG on Johnson cotton ear buds tube. I have a wide selection of parts, VHF transistors, fets, loopsticks, variable caps.,Ĭan anyone here point me to a schematic for an FM receiver that I mightīe able to construct successfully? (no commercial equipment schemas, please, I'm not With key components grouped tightly, built over a ground-plane pcb. My construction choice is Manhatten/island-pad, I'll admit, these were simple designs, using one or two transistors, and (no oscillation, or fleeting/fading/weak reception of the strongest local station.) Tried about 5 designs for FM receivers (google search) with mediocre results. ![]() Shortwave designs, and have had great success with these. I have already built a dozen AM radios (crystal/regen/reflex), some simple Greetings! I have come to this forum out of a desperation to findĪ circuit or schematic that, when built, will be able to tune FM ![]()
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