AudioGuru's FM Receiver

Discussion in 'Wireless & RF Design' started by Shelton, May 9, 2008.

  1. Shelton

    Thread Starter Member

    Mar 13, 2008
    19
    0
    Hi AudioGuru

    I am contemplating building your Superregen FM receiver and was wondering about a couple of things.

    http://forum.allaboutcircuits.com/attachment.php?attachmentid=2201&d=1203528499

    1. How high in the VHF band can I pick up signals - i am looking at receiving signals at about 120-130MHz for Air Traffic reception (AM)

    2. Is the variable cap 60pf or 6pf?

    3. The 150uH is how many turns ?

    4. How long is the antenna ?

    Thanks for your answers

    Shelton. :)
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Audioguru built a supergen? :eek:

    Are you sure it wasn't his evil twin Skippy who built it?
     
  3. mik3ca

    Active Member

    Feb 11, 2007
    189
    0
    am I the evil twin skippy? LMAO
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    A super-regen is a lousy radio.
    It has poor sensitivity and poor selectivity. It overloads easily by strong local stations. It has an AM detector but its audio level depends on the signal strength because it doesn't have AGC like real radios have. It causes interference on nearby radios.

    It is junk. I copied that circuit from the internet and don't know if it works. Look it up to see its construction details.

    When I was a kid I made a crystal radio plus an audio amplifier to hear airplane communications. It worked very well but its audio level also depended on the signal strength.
     
  5. mik3ca

    Active Member

    Feb 11, 2007
    189
    0
    then the receiver I made wasn't a normal "super regen", because when it is used with a transmitter tuned at the correct frequency or strong harmonic, the signal remained constant as I walked away from the transmitter until I am about two blocks away, then the station faded in and out every two steps I walked. The sound volume did not decrease. the signal was real loud when it was about 1 meter away from the transmitter.

    I like my receiver design.
     
  6. mik3ca

    Active Member

    Feb 11, 2007
    189
    0
    I wanted to mention that their first two transistor stages are very similar to mine, but I find the regen resistors rediculously low in value. I think this receiver is more suitable for the AM band. I replaced their 3rd and 4th stage with Harry's homebrew transistor power amplifier. This can be found if you use "push-pull transistor amplifier" in a search engine.
     
  7. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    An AM radio has an output level that depends on the level at its detector. All AM radios (but not super-regens) have AGC so that a weak distant AM station is the same volume as a strong local station.

    A super-regen is an AM radio without AGC so its output level depends on signal strenth.

    A good FM radio has plenty of RF gain so the signal at its detector doesn't depend on signal strength. Weak stations and strong stations are at the same volume level.
    They use AGC in the RF section to avoid overload from strong local stations.
     
  8. dileepchacko

    Active Member

    May 13, 2008
    102
    1
    Instead of going for that circuit. you can try this circuit. Its an redly available IC , which is having the capabilities of receiving week signal. see the attachment file. The two FM radio is making by the use of BA1404 and TDA7000 IC's
     
  9. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
    10
    You copied the circuit? Frankly! :eek: :)D)

    I am anxious to see a project of yours...
     
Loading...