HecaWorld One transistor FM Receiver.3GP

One Transistor FM Receiver.

As promised in our One-Transistor FM transmitter video, we adapted our One-Transistor FM transmitter into a One-Transistor FM receiver. Many times I had noticed that when I place my home made FM transmitter near an FM radio receiver and tune the inductor or variable capacitor of my transmitter, I was able to 'bring in different stations into the FM receiver'. I had wondered what kind of interference this might be and also wondered if I could as a matter of fact, use this transmitter as in receiver with slight modification.

I did not pursue that idea because my team, Itumaful, St. Udu, Prince Collins, St. Chijioke and Spako, figured out a way to use other integrated circuits to build the FM receiver for our projects. It was not until last week that I saw this video by decod31 (credit to him for posting the video and all his tips) that I decided to resurrect my passion for a simple FM receiver....and a few hours later....here we are with a decent low power, low cost FM receiver.

Here we used a general purpose NPN transistor to build this simple FM Receiver. All other parts are from old electronics junks. The core of this circuit is the FM transmitter, there is only one more addition which is the 3pF capacitor acting as the receiving antenna.

Our target was to use minimum voltage supply, we tried a single 1.5V AAA battery but the audio signal output was very low, so we upgraded to 3V (2 X 1.5V AAA batteries) and it gives a decent audio output.

Please, post your comments.

Category:

Science & Technology

Tags:

• Simple
• FM
• transmitter
• radio
• Transmitter
• Heca
• Hecanet
• HecaWorld
• James
• Ugwuogo
• Technology
• HecaTech
• +9J

[90asadali]

hey friend...i have a question.in this schematic, the output from the 104 capacitor goes to amplifier but my amplifier has two inputs (+ and -). so please tell me about this configuration.should i connect the output from 104 capacitor to + of amplifier or - of amplifier??

and if i connect it to positive of amplifier then where should negative of amplifier be connected?

[hecanet]

@90asadali Hello Friend, one input pin goes to ground and the other goes to the 104 capacitor.

So, the -input should go to ground and the +input to 104 (and am assuming that by two inputs you mean two terminals. If that is not what you mean, please, send us the schematic and we'll help you out).

[demimonster08]

Hi.. can you tell us more about the amplifier ckt you used in your receiver?

[hecanet]

@demimonster08 Hey Friend...it was just a hamburger Speaker (amplifier). Google it to see the image.

[gogse100]

I would like to know if I can use any value of an inductor or not

[hecanet]

@gogse100 Yes. Any inductor value would do. Remember that frequency is a function of inductor and capacitor. F = 1/(2*pi[LC]). Where L is inductor value and C is capacitor value.

Just use any telephone wire wound on a pen or pencil. Make 5 to 8 turns (air core) and you will be fine.

[demimonster08]

@hecanet oh i see. thank you

[osalexandeko]

Nice example,and excellent work man!The main idea is to get 2 freqs mixed together and difference is the audio.Colpitts oscillator,is not very linear,but it is used here,we get 2 voltages V(w) and V(w+w1),where w1 is audio,so on the BJT we get something proportional to exp(A(V(w)+V(w+w1))),A=const, second term of Taylor series:(A(V(w)+V(w+w1)))^2 which contains 2*A(V(w))*V(w+w1),so we get the mixer output of V1(w1) and V2(2w+w1)! V2(2w+w1) and V(w) are filtered by audio amp.

[Slovenija12345]

@hecanet

thanks for answer!