This is probably the simplest radio receiver circuit that one could ever imagine of making. The circuit is so simple that it could be finished assembling within a few minutes and you are already listening your favorite programs over it.
Introduction
What are the fundamental criteria associated with radio reception? An antenna stage, a band selector stage, a demodulator stage and a receiving element.When all of these come together radio reception becomes as simple as a piece of cake.
The circuit of a single transistor radio shown here though looks pretty ordinary, yet incorporates all the above stages and becomes just suitable for receiving the nearby radio stations.
However simplicity will always involve some drawbacks also, here the present design will be capable of receiving only strong stations and also selectivity might not be very pleasing, typically if there are a couple of strong stations mingling around the band.
Simulation and Working
The figure below shows how the single transistor radio can be made, we can clearly see that it just involves a single transistor as the main active component.A regular type of MW antenna coil has been used for collecting or sensing the MW receptions.
The coil is tuned using a GANG condenser or a variable capacitor which is connected in parallel to the antenna coil.The coil and the GANG together form a resonant tank circuit, which lock on to the received or the resonant frequency at a particular setting.
The concentrated but very low in power signal from the above LC tuned stage is fed to the base of the transistor which as performs the function of a demodulator as well as a amplifier stage.
The coupling capacitor at the base of the transistor makes sure only the radio information passes to the transistor while the DC component from the supply is appropriately blocked.
Headphone Becomes the Load and the Switch
A 64 Ohm headphone becomes the collector load of the transistor, where the demodulated and amplified signal is applied.
When connected, the received signals can be distinctly heard over the headphones with this little “audio marvel”Plugging in the headphone initiates the circuit and the circuit starts operating with its functions and the switches OFF itself when the headphone is removed from the circuit.
This eliminates the need of an external switch to be associated with the circuit, making the unit very compact.
The circuit requires just 1.5 V for operating which can be implemented using a single button type of cell.
You would also want to build this ONE TRANSISTOR FM RADIO CIRCUIT
Addis says
I can use s9018 instead of BC 547
Swag says
yes you can
praveen kumar kulhari says
ser what is 500 pf gang
praveen kumar kulhari says
please make video for explan it
praveen kumar kulhari says
ser please tell me about every component of this FM circuit
please show me pic of every component and tell me its full name like pf etc.
and tell me its values please please
Swagatam says
praveen, this is not FM, it is an AM circuit, if possible I'll update it with the required details.
praveen kumar kulhari says
ser please tell me about every component like trangister, ressisters,capictor etc.
ser please show me a pic of very component
ser also tell me full name of every component and its values
like 500 PF GANG what is this tell me all please please
Peter Pollak says
The schematic is wrong,the capacitor in the base of tranzistor isn't eltrolythic,is a 100 nF ceramic capacitor
Swagatam says
sorry, your assumption is not correct.
Syed Rafay says
Hi, I have made this circuit but it is unable to catch any FM signals (I just need to catch 1 channel).
can you tell me coil's specifications (thickness, diameter and turns) ?
Swagatam says
Hi, This is not a FM receiver, it's an AM radio.
Swagatam says
in this circuit it could be for 3 reasons:
to stabilize the 1.5V when a strong reception is detected,
to ground unwanted high frequency response and to make the audio clearer.
to safeguard te transistor from earphone coil back emfs…
rokic95 says
can you please tell me why we wire capacitor between colcector amd ameitter?
Swagatam says
to keep the voltage stabilized and maintain the selected frequency….
daniel inoo says
what is the height of the antenna
Swagatam says
the longer the better….2 meters can be tried initially.
PSK™ says
Good day sir
Will this capture FM signals?
I used BF199-based replacement Transistor istead of BC547. and used Standard FM Tunning Gang CAP paralleled to Standard MW AM antenna coil.
Will this work?
Swagatam says
Good day PSK, I don't think it's designed for reeving FM, it's specifically intended for MW reception
Gus Smith says
I made this and it is working. Fed the signal into a LM386 and can hear it on a 8ohm speaker. Too bad I can only 2 clear stations.
Michael Mueller says
Can you say anything about the power consumption of this circuit?
Thanks in advance!
Swagatam says
not sure, but the 1.5V cell would last for years.
Michael Mueller says
Okay, thank you for your informations!
– but I still have one another question about your circuit:
What do you think – how is the quality of the received sound, if I build a FM receiver just some meters next to the receiver? – do you think, the sound will be good or have you any other idea, how I could realise this?
I'm asking, because I want to make a pair of headphones wireless – but with power consumption as low as possible.
Thank you in advance, Mr. Majumdar!
Swagatam says
Sorry, I did not understand your question, what an FM receiver has to do with the above circuit?
The above circuit is a receiver not a transmitter
Michael Mueller says
Please excuse me, I actually wanted to ask you, how good the quality of your published receiver is?
I wanted to ask you that question, because I intend to build your fm receiver and a fm transmitter.
From last one (transmitter), I want to transmit an audio signal to a pair of headphones, which I want to make wireless due to your receiver circuit?
You know what I mean? – Basicly I just wanted to know, what you think about this idea and if the quality is good enough.
Swagatam says
sorry but you should put the question under the relevant article, because i have so many transmitter related articles, can't really figure out which circuit you are referring to.
anyway all my circuits are correct and will surely work if done correctly.
billy biddles says
you said you can be hired, if we pay you. will you thumb my bum while watching german piss porn for $50? i dont have hair on my balls.
Swagatam says
I'll do it free of cost for you, however may be you won't appreciate my service as I would come armed with a red hot iron and nutcracker equipment…..be ready
Scott Hymel says
HOW MANY TURNS IS THE COIL AND AT WHAT TURN IS IT TAPPED ?
Swagatam says
Use a standard radio MW receiver antenna coil.
Swagatam says
can't say you'll have to test it practically…
Manas Ghosh says
CAN YOU PUBLISH "L BOARD" PRINTED DIAGRAM OF AM RECEIVER?
Swagatam says
it's an obsolete design now….sorry I don't have it.
Manas Ghosh says
i am trying to make this, if i have got any problem can i mail you? also inform me, can i not connect speaker instead of ear phone?
Manas Ghosh says
my home is near 25km from radio station, will it work?
Swagatam says
speakers won't work here, you'll require a pair of headphones. It will catch only the strongest nearby stations, not the weaker ones.
shadab says
you told that any parties in Mumbai can hire you for project. I am from Karnataka, Dharwad. I am studying in kendriya vidyala dharwad ,7th standard. I am really interested in electronics.will you help me while making my projects? I tried 4 radio receiver circuits, in fact they failed. Are you sure this circuit will work?
Swagatam says
Yes, however by hiring i meant paying for my services, but don't worry you can ask me questions in this blog, i'll try my best to help you out….
shadab says
will you make a radio circuit which can produce sound in a 9 ohms speaker.
Swagatam says
You can try the following circuit:
https://homemade-circuits.com/2012/10/simplest-am-radio-receiver-with-speaker.html
shadab says
will this work 7 km far from radio station?
can we replace a speaker in the place of head phone?
Swagatam says
7km is relatively near, so the circuit should work.
A speaker will not produce any sound, it can be only heard through a headphone.
Anonymous says
Is there are any fm reciever circuit in your blog? This circuit is very simple but don't recieves fm stations.
Swagatam says
I think if you Google a bit you would find a couple of simple circuits…..one that uses 40106 IC is pretty simple to build I guess.
Anonymous says
Can you please publish a simple transistor fm reciever?