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  • Perhaps this is one of the simplest and smallest FM radio receiver that can receive the FM stations available locally. Its simple design makes it ideal for a pocket sized FM receiver. The output of the receiver drives a head phone.

    The circuit works off a small 4.5 volt battery or two 3.6 volt Lithium button cells.
    The fm receiver section has two RF transistors T1 and T2 to detect the Frequency Modulated signals. Coil L1 and the trimmer capacito form the tuned tank circuit to tune the receiver to the best FM station with strong signals. The signals are capacitor coupled through C2.

    Tiny FM Radio Receiver Circuit Schematic

    small fm radio schematic

    small fm radio circuit schematic

    10K preset VR controls the volume to the input of the amplifier. IC1 is the micro power audio amplifier that works between 4.5 to 12 volts DC. The amplified sound can be heard through the low impedance head phone or small Mylar speakers.

    FM radio coil
    Coil is the important part of the FM tuner. It is made up of 18 SWG enameled copper wire. Wind 4 turns on a ball pen to get 0.5 cm inner diameter. Remove the enamel from the tip of the wire and solder tightly in the PCB. Trimmer and coil should be soldered very closely. Adjust the spacing of the coil winding if necessary to get the station clearly. Assemble all the receiver components as close as possible to get better result.

    Pinout of BF494 and LM386

    bf494lm386 pins

    attentionThe author D Mohankumar is not an active member anymore. Please take into consideration that the presented information might not be correct.
    
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    58 Responses to "Small FM Radio Circuit"

    1. Saha Fingia says: on February 21, 2010 at 9:27 am

      This radio circuit won’t work because T1 and T2 have DC shortcircuit between the collector and base. I think this fm radio has not been tested and is clear that won’t function, please don’t post untested schematics.

      • I made this circuit for school project and didn’t work .

      • I build this circuit just today, transistors mpsh10,instead of R1 I took 20K and instead of lm386 – just amplifier for pc,and it does work,I can listen to some local stations,it is great regenerative FM radio that is perfect for beginners!!!

      • i build the circuit i don’t why not working if can somebody help or support if somebody wants to see my connection let me know

      • Gus Smith says: on February 25, 2014 at 8:44 pm

        I also used 2x MPSH10 but I only receive two strong AM channels. What can I have done wrong?

      • why did they put up some thing like that?is that a test?

    2. D Mohankumar D.MOHAN KUMAR says: on February 21, 2010 at 1:19 pm

      Try to construct and then see the working.T1 and T2 form an oscillator with trimmer and coil as tuner

    3. shahab hashmi says: on April 13, 2010 at 6:48 pm

      i make this ciruit but it have havey noice when i tuch the vr 10k ….. i dont know how it is work Plese define it .

      thank you .

    4. let me try this at ma home

    5. I`ve build the receiver stage with 2 BF199 and it works just fine :)

    6. shreddy says: on March 8, 2011 at 12:52 pm

      It just cannnot work,there is no FM detection circuit in it ,to recover the audio from the frequency modulated wave,similar to detector diode OA79 in AM radio circuits.

    7. it wont work ,test b4 u keep

    8. I think this circuit makes a “tunnel diode” from two transistors, the operating voltage must be adjusted with care, and the tuner uses “slope tuning” to detect FM. I would use a 25 or 50k ohm pot in place of R1 and adjust for best results, then use a fixed resistor of the closest value.

    9. I can confirm that this circuit is working :)
      Only problem is body-capacitance issue.

    10. I build this cct and it is working just fine :-)

      • i have also made fm circuit this but it is not working .
        i have used simple wire in case of telescopic areal
        plz help.

    11. hi.please tell me value L?tank you DR.

    12. http://electroschematics.com/5150/tiny-fm-radio/

      C2 and C3 values are not clearly indicated.
      C2 0.22 uF or nF ?
      C3 0.1 uF or nF ?
      Please reply ASAP.

      • Since they must pass the audio signal these are in uF. Tunnel Diodes are very expensive, this is a poor man’s Tunnel Diode. I have played around and got a similar circuit to oscillate in the audio range. The two transistors will fight each other to turn on and the result is oscillation.

    13. hello all friends
      I build this tiny radio and it work
      weakly , I think we must add good amplifire to it.

    14. Is the circuit really working or not? i can’t decide because of the opposite comments.
      i need a project for my circuits subject.
      i need HELP!

      PLEASE REPLY ASAP

    15. Did you use uF for the C2 & C3 ?

    16. We built the circuit and is working just fine… But i was hoping if some one could help me why there are two transistors in this circuit.
      plz help

    17. P.S which is the demodulator in the circuit?

    18. @ Archie, The two transistors form an oscillator much like a tunnel diode, at a certain bias voltage these transistors will fight each other to conduct while turning the other transistor off. If bias is set to a point just before this happens, the circuit becomes regenerative & demodulation occurs when the FM signal is tuner a bit lower or higher than the FM carrier and “slope tuning” is the result.

    19. If you build an AM receiver that will tune to the FM band, you can hear the FM sound if you tune down or up from the station. this is called slope tuning, but this tuning method is subject to noise since it is not a real FM demodulator.

    20. hi there,
      I made this circuit on bread-board with BF199,and i just heard whistle on earphone :(
      …I need help…
      Do you know where did i have mistake?
      Shall i make it on PCB?
      Does BF199 works with this?

      thanks a lot :)

    21. Navratna Pandey says: on May 19, 2012 at 10:00 am

      I have made this circuit instead of ear phone i am using 8 ohm speaker but this one is not picking the fm signals and instead of 22pf trimmer i am using the variable capaictance of 22 uf can u help me more in this circuit instead of telescopoic areal can i put a long insulated wire?

    22. DOCTOR GIRMA GEBREGZI says: on June 9, 2012 at 8:58 am

      THANK U. AM DOING THIS CIRCUIT AT MY HOME. IT WORKS PROPERLY.BUT TELL ME ALL THE CIRCUIT OPERATION.

    23. monsterkodi says: on July 21, 2012 at 2:07 am

      This is a nice little circuit! It is quite tricky to get it to work, but it is worth it. I attached it to my buildings TV antenna and use a big variable capacitor (~400pF) with a ~25 turns coil to receive international radio stations from around the world! My suggestions to anyone who wants to try this: replace R1 with a pot to fine tune (I use a 10k pot in series with a 15k fixed resistor). And use pins 1 and 8 of the LM386 to raise the gain when receiving weaker stations.

      Thanks to the webmaster for posting this and the other circuits.

    24. Does s9018 1.1ghz transistor will work better or not

    25. Hi I am a year 12 student and want to build a radio. My local radio stations broadcast between 88-108M Hz will this radio work? If not how could I modify this circuit diagram?
      Thanks

    26. sohini bose says: on October 30, 2013 at 11:49 am

      can u please mail me the details of the above circuit.please mention how and where demodulation is being done.it’s urgent.

      • As I wrote before the two transistors are set to fight each other at a certain bias point, so they try to take the current and turn the other transistor off, this makes oscillations like the tunnel diode. Demodulation happens when the station is not tuned in exactly in what is called slope tuning. As the signal changes frequency it gets tuned in more and less which results in demodulation. This is easier to explain in a drawing. An AM radio will pick up FM if it is off tune a bit, but you still get the static since it is not a true FM demodulator.

    27. Is this circuit working?

    28. I just spent the last hour reworking this circuit for AM reception on my SK10 panel (solderless breadboard). It may take a bit of futzing around trying to match 2 transistors to make it work properly at AM frequencies. After trying 2 BC337s and 2 BC547s, the 547s worked out better. I did not have an LM386 amplifier set up so I just used a one transistor audio amp and a pair of earbuds (64 ohm).I found that the circuit worked better at the top half of the band (I used a 400pF tuner cap and a ferrite bar antenna coil with 57 turns wound close on top of a layer of paper to get the AM band in) and despite some inconsistencies, received all local stations and about 8 remote stations, including 4BU up in Bundaberg (I live in Brisbane, Australia)Some of the stations seemed weak in signal output but about 4 of them came in with real clarity and excellent sound volume. Making it work on FM could be difficult but not impossible and the BF199 transistros are absolutely at those frequencies.The BC547s should be OK if you just want to try it on AM and also try an antenna wire and a groung wire – you may get better results than you bargained for…Austin

    29. PS – one more thing, it’s a great circuit to build on a budget and it will work if you persevere with it. I used a 12k current limiting resistor for the 2 BC547 transistors connected to a 9 volt battery as well.

    30. Rajeev says: on June 7, 2014 at 8:03 pm

      Yes. I made this small FM radio. It works well. Local station is received even without antenna. Some experimenting is however needed to achieve good results.I made following changes. 1) used 20 swg enamelled copper wire for coil with 7 turns.2) used plastic gang capacitor used in pocket radios in place of trimmer. 3) used 10k fixed resistor and 10k lin pot in series in place of 22k R1.4) used ear phone from old telephone hand set 5) joined pin 1 and 8 of IC using 10Mfd 25V electrolytic capacitor, positive end of capacitor to pin 1 and negative end to pin 8.
      The station is tuned using gang capacitor. If need be the coil winding has to be adjusted by slightly pulling the winding apart to get clear reception. The 10k lin pot used in series with 10k fixed resistor used as R1, has to be adjusted to get clear and loud sound. It’s great fun to experiment with this simple and intersting FM radio. It does work.

    31. Hello,

      This is not working for me. I built this circuit in two parts, the tuner part with the transistors and the tank circuit on a perforated board and the amp circuit on the breadboard which of course I connected the two parts toghether with an aligator clip and also connected the emmiters with aligator clips. Instead of the BF494 I used the 2N3904 which also seems to have the Ft high enough for RF. Also, instead of the LM386 I used a MC1458 op. amp. circuit which was pretty loud for an older microphone amp. circuit I built. Also, I tried many values for R1. The only problem I see is the tuner part is not oscillating. Some tips?

      • The 2N3904, or BC547 will not work. I’ve used BF494, BF199, BF324(pnp) and even the BF198 and they all worked just fine. Some obvious changes needs to be made if you want to try the BF324 because its a pnp transistor

      • Thanks, I’m ordering some parts today. I’ll keep you guys posted after I’m doing some more experimenting. Would you care to say why it doesn’t work?

      • Please go through the posts given below. The tips given there should be helpful to you I hope. The power supply can also be raised to 6VDC.

      • Hey Rajeev. I was refering to why the 2n3904 doesn’t work. I think it has something to do with capacitance.

      • 2N 3904 is not suitable for VHF range (FM). It will not oscillate. Focus more on RF section of radio. The tank circuit, BF 494 transistors and R1 (18K fixed and 10 K LIN POT in series). This is regen receiver hence station needs to be tuned using gang capacitor and 10K LIN POT to get best reception. 10K LIN POT for fine tuning. Begin first with 8 turns of coil 8mm inner diameter then reduce turns and dia if need be. Sometimes spacing between the turns also has to be adjusted either by compressing or pulling apart the turns slightly. This is what is main experimenting. Use platic knobs for gang capacitor and 10K LIN POT as hand capacitance could interfere with tuning. However with little practice it is enjoyable experience!

    32. Hello!
      I once again assure all that the circuit works. Few tips I would like to share.
      Bear in mind that it is a LOCAL FM Radio hence locally available strong stations are received. It is not a ‘ regular ‘ radio in that sense but a hobbiest’s toy radio. Some experimenting and a lot of patience and perseverance is needed to achieve final result. You will see only 11 parts are used in the circuit. I didn’t use volume control ( 10 K pre set ). The volume of my radio is just loud enough to be heard through the head phone ( head phone, not loud speaker! )
      First of all, do not deviate from the schematic. Once you achive the result you can then make changes, improvise the circuit and then even share it with all. The semiconductors BF 494 and LM 386 are easily and locally available. They are not costly. Wait till you get them. If you use alternate equivalents, the experimenting will be more and results are uncertain then. Keep patience.
      Try the circuit on breadboard as I did.
      Most crucial part is tank circuit. Diameter of coil and number of turns will have to be varied till you get final result. I used plastc gang capacitor. The number of turns of coil could be anything from 4 to 9. Find it experimentally. There is no escape. Keep patience.
      Make ‘ audio ‘ section first. Minus 10K preset, it needs 5 parts only as per schematic. However I will recommend to connect pin 1 and 8 of IC through 10 mfd capacitor to raise the gain. Power the audio section and touch pin 3 with finger. You should hear loud ‘ hiss ‘ through head phone ( not speaker! ). Now connect ‘ RF ‘ part which has only 5 parts including R1. For R1 use 18k fixed resistor and 10K LIN POT ( LIN, not LOG ) in series. Check the connections of BF 494 pair. Emitters are common and go to negative end of power supply. Collector of one transistor is connected to base of another transistor.
      Good Luck!

    33. Here is the picture of Small FM Radio I assembled on a small acrylic sheet. Various parts can be seen. A plastic gang capacitor with orange coloured knob, ear piece from old telephone set boxed up in transparent case, 10K LIN POT with knob, coil directly soldered to gang capacitor, two transistors BF 494 next to coil, IC LM 386 with 10 mfd electrolytic capacitor connected between pin 1 and 8 of IC, two green coloured 0.1mfd capacitors in parallel connected directly to pin 3 of IC ( I did not use 10k preset )….etc.

    34. What are the voltages of the capacitors. Please reply ASAP

    35. Hello!
      I converted the Small FM Radio schematic into an ’8 pin IC Schematic’. This can be an interesting project to make. FM Radio with ‘home made’ IC! Total 9 parts are used in this IC. The parts are – T1 and T2 BF 494 transistors, T3 IC LM 386, R1 18K resistance, C1 0.22 MFD, C2 10 MFD 25V, C3 0.1 MFD, C4 220 MFD 25V, D1 1N4007. Pin configurations are – 1 and 2 to tank circuit, 3 and 4 to 10K LIN POT, 5 and 6 to 6V battery 5 to + end 6 to -end, 7 and 8 to head phones/ear phones. If the readers are interested, I will also post components layout.

    36. if i use for T1=S9018 and T2=BC327 and IC=LM741 will it work

      • Plz refer to my earlier post of July 17. Most of the things are made clear there. Plz adhere to the schematic. The rate of failure is always more in all RF projects if you deviate from the schematics.

      • Yes it’s a good idea to stick to the schematic and to what others have said in this post. I made this work with the bf199 but I could only pick up 1 local station in my city. I noticed this circuit goes out of tune after 5 to 10 minutes, maybe because the components are getting hotter. Can somebody confirm?

    37. ii used that and i get only the sound but not frequency

      • Well notice that the tuner part is very sensitive so you have to solder it on the perf board. You can leave the lm386 on the breadboard as I did. Cheers!

    38. I finally built this circuit using the BF199, and boy it wasn’t easy!……This circuit takes a lot of tinkering and patience.

      At first i got only an AM station (the strongest in my area).

      Then i twacked the circuit a little bit and i got four FM stations, but due to my excitement and shaky hands, i mistakenly shorted something!!

      ……Sadly that was the end of my FM reception,for i never got it to work on the FM band again! :(

      At that point i had nothing to loose as my radio only got one stupid AM station and nothing else!

      ….With nonchalant experimental radicalization surging through my vains and my tongue sticking out of my mouth in a bid for quintessential concentration.i did a lot of horrible things to my radio, half of which i don’t even remember.

      …..but in a not shell it had to do with a lot more number of turns, coiled on a ferite core.

      After that i connected my 6 volts battery once again to the radio…..

      THEN BAM!!!!…….the most amusing thing happened!

      I began to receive SW stations, granted they where not very clear but at least a got to hear BBC, Italy, Indonesia and German stations!!!

      Boy was it a Wild ride!!!…..With less than a dollar and few hours of my time spent working on it, i got to experience AM, FM and SW all in one day!!!

      ….Now i can’t stop, but think what more i can do with this circuit?

      Thanks electroschematics Geeks!….you made my day. xoxxoxoxxx

    39. Well done Xixicx!…… Plz do share your findings after your next experiments. Good luck!

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