Can you design AM Radio with only "1" Active element?

Discussion in 'Wireless & RF Design' started by staryly, May 8, 2016.

  1. staryly

    Thread Starter New Member

    May 8, 2016
    My goal is to build an AM radio for receiving in and around the 531kHz ~ 1602kHz frequency.
    BUT there are some limitations.

    1. Use only one Active Element (Diode, TR, IC...)
    2. The free availability of passive element (R, C, L...)
    3. Only one DC Power Supply.
    4. AM Radio must be able to receive more than 3 channels.

    so, I have designed basic AM Radio with envelope detector.
    but I want to improve performance of radio in terms of QoS(Quality of Service).
    How can I upgrade my radio?
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
  3. recklessrog

    Well-Known Member

    May 23, 2013
    Well, this is interesting, a little while ago, we were having discussions as to whether a diode is "active" and it depends on the application and your interpretation of "active" If you consider a diode as passive, then a crystal radio uses no active parts and vice versa.
    There used to be a little metal cased 3 pin (I think) a.m radio chip that only needed a tuned circuit, a couple of resistors, battery and earpiece. Someone on here will remember it better than me.
    Try googleing T.R.F a.m receiver.
    Just remembered the chip was an Zn414
    Last edited: May 8, 2016
  4. BR-549

    AAC Fanatic!

    Sep 22, 2013
    recklessrog likes this.
  5. recklessrog

    Well-Known Member

    May 23, 2013
    Yes that's the one I was thinking of, I wonder if they are still available. They were from the early seventies if I remember correctly..
  6. BR-549

    AAC Fanatic!

    Sep 22, 2013
  7. RichardO

    Late Member

    May 4, 2013
    Maybe what you want is a reflex receiver.
    Note the single active device!

    Oh, drat it has a carborundum point contact diode. :D