See the theory part:I disagree, a capacitive voltage divider does not matter. The capacitor between the collector and emitter simply provides positive feedback so that oscillation can happen.
Also, the transistor collector does not have "negative resistance".
Wikipedia shows a voltage divider with two capacitors at the emitter but this circuit has only the feedback capacitor from the collector to the emitter. Stray wiring capacitance will add a small amount of voltage divider action that does not matter.
Wikipedia discusses the negative resistance of a different Colpitts oscillator with feedback from the emitter to the base.
Did you build it? Did it work?
Your schematic of the super-regen FM tuner is marked "Swagatam Innovations" which is a hobby site in India. Didn't you see the project that I could not find there? Didn't the project have instructions about how to make the coil?
I looked at FM Super Regen in Google and most circuits use a coil of 5 or 6 turns around a 1/8" to 1/4" former (3 to 6mm) and the turns have a small spacing so they do not touch each other. Then turn the variable capacitor to tune in FM radio stations.
Try using a 40cm wire as the antenna connected to the emitter of the transistor as shown in the similar super-regen FM tuner I posted.
Since FM radio is at a very high Frequency then the way the parts are connected together is important. A pcb is usually used but I use a compact stripboard layout for my circuits. It will not work if you build it on a solderless breadboard because there is too much capacitance between the strips of contacts and wires.
Do you need an FM radio that works well, or are you simply learning how to solder parts together?
This circuit is so simple that it has some serious problems if you can fiddle with it to make it do anything:
1) It is overloaded by strong local radio stations.
2) It has poor sensitivity so it will not pick up weak distant stations.
3) It has poor selectivity so more than one local station might be heard at the same time as another local station.
4) Since it does not have a proper FM detector it picks up all kinds of AM pops, clicks and buzzing interference.
5) Since it does not have a proper FM detector then it produces pretty bad distortion, depending how you tune it.
6) Its tuned radio frequency and amount of distortion will change as the battery voltage runs down and if the temperature changes.
Maybe you should make a kit FM tuner instead. Many years ago my first electronic projects were a kit power amplifier and a kit FM tuner. The kits came with all the parts and a pcb. They were designed properly, worked perfectly and performed very well.
The TDA7000 radio IC is obsolete and had poor performance. It was replaced by the TDA7088 that also had poor performance. A "radio" with a TDA7088 can be purchased at The Dollar Store for only one dollar. I have two of these awful "radios".
The "radio" comes with a battery and earphones so the actual "radio" is free. The TDA7088 scans for the next radio station but frequently misses a few.
Why aren't you learning about electronics in school?? You need to learn about a real radio circuit that is used in almost every radio, not this extremely simple super-regen or a crystal radio.
Why do you want an oscillator? Why make an amplifier with high voltage, low current 2N5551 transistors? A speaker needs high current not high voltage.
thank you, why you think here i cant find?
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