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?
@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).
@hecanet hello friend..sorry to bother you again.i have a problem.i have used two different amplifier circuits and they both become AM receivers.so instead of amplifying output of my receiver they amplify their own catched station with noise of my receiver and when i turn knob of my gang capacitor, it has no effect on output.what should i do??
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.
@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.
@mubarakmohd12 Hello there, the BOM is part of the schematic already, but here they are again: - 2N2222 - General purpose NPN Transistor; 1uF capacitor - decoupling capacitor; 2k2 Resistor - Biasing Resistor; 4-turn inductor and Trimmer capacitor - 3 to 100pF - part of tank circuit, 104 (100nF) - output to antenna or audio amplifier; 101 (100pF) - part of biasing circuit; 150 ohm resistor - temp stability and 1.5V battery for power supply.
@Slovenija12345 The secret, which is in fact no secret at all, is that the FM transmitter which is the fundamental part of the receiver is a voltage controlled oscillator. Therefore, to stabilize your receiver, you need to stabilize your base circuit. Use a voltage regulator in the power supply line. use, say 7805 to provide 5 volt regulation.
Secondly, you need RF shielding; this ensure no external interference. Metal 'can'/shield will suffice. Use Plastic handle for the tuner.
@mubarakmohd12 Did the 1-transistor Transmitter work for you? You need to start from somewhere, and I strongly recommend completing the 1-transistor transmitter first.
The reason for that is that 'the 1-transistor transmitter is your building block for the receiver'. Once you complete it and it is working, that same circuit will act as a receiver with minor modification.
Use 3 to 100 pF variable cap. I also used a salvaged part. Use any telephone wire for antenna. No critical parts needed.
@mubarakmohd12 Way to go attah boy. That 'hissing sound' is such a cool feeling. Now, all u need to do is find the right combination of the inductor and capacitor that gets u a good FM station.
Sometimes u need to stretch the coil a little bit. Take a look at our video and notice how the coil was 'deformed'. It is not a clean wound '4-turns' but stretched and sometimes compressed.
Try dividing up the coils into 2 turns on each side as in our video. Try compressing and expanding as well.
One more tip: Build the 1-transistor Transmitter (TX) first. Make sure it is working within 88 and 108 MHz. That is ur building block for the reciever (RX)
Bring ur Tx close to an FM radio tuned to a no broadcast band. Tune the Variable cap of ur Tx. U might notice that as u tune ur Tx, the other Rx picks up a radio station that it was not tuned to
This 'stray' station is most likely the one ur Tx-turned-Rx is 'listening to'. Connect your amplifier and you are 'home and dry'
One more tip: Build the 1-transistor Transmitter (TX) first. Make sure it is working within 88 and 108 MHz. That is ur building block for the reciever (RX)
Bring ur Tx close to an FM radio tuned to a no broadcast band. Tune the Variable cap of ur Tx. U might notice that as u tune ur Tx, the other Rx picks up a radio station that it was not tuned to
This 'stray' station is most likely the one ur Tx-turned-Rx is 'listening to'. Connect your amplifier and you are 'home and dry'.
@mubarakmohd12 Break your circuit up in 3 sub-sections:
1. Output amplifier - Test this separately to make sure it is working. Use a small signal input source to test it.
2. Connect the pre-amp to the input of your output amp and make sure the 'combo' works well. For the pre-amp, no strict component is required, the only thing is to get enough gain for your weak Radio signal
3. Connect the 1-transistor FM receiver. 2N2222 works great with it. If you still have issues, let me know.
1. Output amplifier - Test this separately to make sure it is working. Use a small signal input source to test it.
2. Connect the pre-amp to the input of your output amp and make sure the 'combo' works well. For the pre-amp, no strict component is required, the only thing is to get enough gain for your weak Radio signal
3. Connect the 1-transistor FM receiver. 2N2222 works great with it.
if you still have issues, let me know and I will guide you more.
@trricklecharge91 'the yellow thing' is foam with wax on it. It was part of an old electronics junk, nothing fancy. We just reused it. But we made other circuits without the foam. They all work alike.
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?
90asadali 1 week ago
@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).
hecanet 1 week ago
@hecanet hello friend..sorry to bother you again.i have a problem.i have used two different amplifier circuits and they both become AM receivers.so instead of amplifying output of my receiver they amplify their own catched station with noise of my receiver and when i turn knob of my gang capacitor, it has no effect on output.what should i do??
90asadali 5 days ago
Comment removed
demimonster08 3 weeks ago
Hi.. can you tell us more about the amplifier ckt you used in your receiver?
demimonster08 3 weeks ago
@demimonster08 Hey Friend...it was just a hamburger Speaker (amplifier). Google it to see the image.
hecanet 3 weeks ago
@hecanet oh i see. thank you
demimonster08 3 weeks ago
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.
osalexandeko 2 months ago
I would like to know if I can use any value of an inductor or not
gogse100 3 months ago
@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.
hecanet 3 months ago
@mubarakmohd12 Hello there, the BOM is part of the schematic already, but here they are again: - 2N2222 - General purpose NPN Transistor; 1uF capacitor - decoupling capacitor; 2k2 Resistor - Biasing Resistor; 4-turn inductor and Trimmer capacitor - 3 to 100pF - part of tank circuit, 104 (100nF) - output to antenna or audio amplifier; 101 (100pF) - part of biasing circuit; 150 ohm resistor - temp stability and 1.5V battery for power supply.
Hope this helps. Post me your feed back.
hecanet 5 months ago
@hecanet
i used 2n2221 a and works but its there any way to stabilize the signal???
Slovenija12345 4 months ago
@Slovenija12345 The secret, which is in fact no secret at all, is that the FM transmitter which is the fundamental part of the receiver is a voltage controlled oscillator. Therefore, to stabilize your receiver, you need to stabilize your base circuit. Use a voltage regulator in the power supply line. use, say 7805 to provide 5 volt regulation.
Secondly, you need RF shielding; this ensure no external interference. Metal 'can'/shield will suffice. Use Plastic handle for the tuner.
God Bless.
hecanet 4 months ago
@hecanet
thanks for answer!
Slovenija12345 4 months ago
My friend thank you very much for this excellent example!!
Would you be so kind to post a bill of material with all values and part numbers ?
anglitoestebancito 5 months ago
@mubarakmohd12 Did the 1-transistor Transmitter work for you? You need to start from somewhere, and I strongly recommend completing the 1-transistor transmitter first.
The reason for that is that 'the 1-transistor transmitter is your building block for the receiver'. Once you complete it and it is working, that same circuit will act as a receiver with minor modification.
Use 3 to 100 pF variable cap. I also used a salvaged part. Use any telephone wire for antenna. No critical parts needed.
hecanet 5 months ago
@mubarakmohd12 Way to go attah boy. That 'hissing sound' is such a cool feeling. Now, all u need to do is find the right combination of the inductor and capacitor that gets u a good FM station.
Sometimes u need to stretch the coil a little bit. Take a look at our video and notice how the coil was 'deformed'. It is not a clean wound '4-turns' but stretched and sometimes compressed.
Try dividing up the coils into 2 turns on each side as in our video. Try compressing and expanding as well.
hecanet 6 months ago
One more tip: Build the 1-transistor Transmitter (TX) first. Make sure it is working within 88 and 108 MHz. That is ur building block for the reciever (RX)
Bring ur Tx close to an FM radio tuned to a no broadcast band. Tune the Variable cap of ur Tx. U might notice that as u tune ur Tx, the other Rx picks up a radio station that it was not tuned to
This 'stray' station is most likely the one ur Tx-turned-Rx is 'listening to'. Connect your amplifier and you are 'home and dry'
God bless.
hecanet 6 months ago
One more tip: Build the 1-transistor Transmitter (TX) first. Make sure it is working within 88 and 108 MHz. That is ur building block for the reciever (RX)
Bring ur Tx close to an FM radio tuned to a no broadcast band. Tune the Variable cap of ur Tx. U might notice that as u tune ur Tx, the other Rx picks up a radio station that it was not tuned to
This 'stray' station is most likely the one ur Tx-turned-Rx is 'listening to'. Connect your amplifier and you are 'home and dry'.
God bless.
hecanet 6 months ago
@mubarakmohd12 Break your circuit up in 3 sub-sections:
1. Output amplifier - Test this separately to make sure it is working. Use a small signal input source to test it.
2. Connect the pre-amp to the input of your output amp and make sure the 'combo' works well. For the pre-amp, no strict component is required, the only thing is to get enough gain for your weak Radio signal
3. Connect the 1-transistor FM receiver. 2N2222 works great with it. If you still have issues, let me know.
hecanet 6 months ago
Break your circuit up in 3 sub-sections:
1. Output amplifier - Test this separately to make sure it is working. Use a small signal input source to test it.
2. Connect the pre-amp to the input of your output amp and make sure the 'combo' works well. For the pre-amp, no strict component is required, the only thing is to get enough gain for your weak Radio signal
3. Connect the 1-transistor FM receiver. 2N2222 works great with it.
if you still have issues, let me know and I will guide you more.
hecanet 6 months ago
Nice work ! It's good that the same components are reused in the reciever circuit. However what's that yellow thing inside the coil(inductor)?
trricklecharge91 6 months ago
@trricklecharge91 'the yellow thing' is foam with wax on it. It was part of an old electronics junk, nothing fancy. We just reused it. But we made other circuits without the foam. They all work alike.
hecanet 6 months ago
Nice Job. I appreciate the work you put in.
Regards,
TheKC1ML 7 months ago
@TheKC1ML Thank you.
hecanet 7 months ago