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Thursday, May 3, 2012

Make this One Transistor Radio Receiver Circuit


This is probably the simplest radio 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.

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, incorporates all the above stages and thus becomes just suitable for receiving the 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.
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.
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 oer 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

27 comments:

  1. Can you please publish a simple transistor fm reciever?

    ReplyDelete
  2. I'll surely try to include one FM receiver circuit in my blog, for the time being you may refer to the following link:

    http://www.somerset.net/arm/fm_only_one_transistor_radio.html

    Regards.

    ReplyDelete
  3. Is there are any fm reciever circuit in your blog? This circuit is very simple but don't recieves fm stations.

    ReplyDelete
    Replies
    1. 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.

      Delete
  4. will this work 7 km far from radio station?
    can we replace a speaker in the place of head phone?

    ReplyDelete
    Replies
    1. 7km is relatively near, so the circuit should work.

      A speaker will not produce any sound, it can be only heard through a headphone.

      Delete
  5. will you make a radio circuit which can produce sound in a 9 ohms speaker.

    ReplyDelete
    Replies
    1. You can try the following circuit:

      http://homemadecircuitsandschematics.blogspot.in/2012/10/simplest-am-radio-receiver-with-speaker.html

      Delete
  6. 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?

    ReplyDelete
    Replies
    1. 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....

      Delete
  7. CAN YOU PUBLISH "L BOARD" PRINTED DIAGRAM OF AM RECEIVER?

    ReplyDelete
    Replies
    1. it's an obsolete design now....sorry I don't have it.

      Delete
    2. 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?

      Delete
    3. my home is near 25km from radio station, will it work?

      Delete
    4. speakers won't work here, you'll require a pair of headphones. It will catch only the strongest nearby stations, not the weaker ones.

      Delete
  8. can't say you'll have to test it practically...

    ReplyDelete
  9. HOW MANY TURNS IS THE COIL AND AT WHAT TURN IS IT TAPPED ?

    ReplyDelete
    Replies
    1. Use a standard radio MW receiver antenna coil.

      Delete
  10. 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.

    ReplyDelete
    Replies
    1. 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

      Delete
  11. Can you say anything about the power consumption of this circuit?
    Thanks in advance!

    ReplyDelete
    Replies
    1. not sure, but the 1.5V cell would last for years.

      Delete
    2. 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!

      Delete
    3. 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

      Delete
    4. 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.

      Delete
    5. 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.

      Delete
  12. 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.

    ReplyDelete

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