Germanium radio
  • Introduction
       I like to make everything so that I can make something except amilifiers. So I will introduce such instruments which has made in recent.

  • Germanium Radio
       I made this small radio inspired by the wonderful book (K. Kobayashi (1996) Our Crystal Radio, Chikuma Shobou, Tokyo, Japan.). As my room seems to be in strong field of radio waves, this radio can detect broadcasts on NHK and local radio station only to connect wire cables to the antenna and ground terminals. I also suprise an efficiency of the crystal phone. This radio can recieve enough to hear, sometimes too strong. Of course it need not a battery!
    • UFO??

    Photo1: Is this a radio?
    UFO??

    Photo2: The backside of this radio.
      I used CD-R media which failed to record data as a chassis! Diode or crystal detector should be connected in the right side terminals. and antenna and ground should be connected in the left side terminals. Detector terminal can connect something to test an ability of the detector. Maybe some crystals can detect a broadcast.
    diagram
    Figure: Schematic diagram of this radio.
       This is the schematic diagrams of the germanium radio. The coil and the variable condencer select a wave frequency, and next, the selected wave are transferedinto electrical signal. At last this signal is transfered into the acourstic sound by the crystal receiver. The efficiency and the impedance of a crystal phone is extremelyt high so that it may be impossible to use a headphone and a speaker instead of a crystal receiver.
    If you do not have a crystal for detector, you may connect a germanium diode instead of a crystal in the detector terminals. I am using a diode named 1N60.

       I propose an easy experiment. If you connect another diode or crystal in the terminals, waht is happen? Can you receive well or not? I once used a small silicon diode named 1S1588. This diode could detect a broadcast. But some large diodes to use power supply cound not receive at all. Why such results occurred? Let's think!

       I think germanium radio is quite simple and it can be made easily. But it has much wonders. If you have never made the crystal radio, I recommend to make it at once. And I guess the crystal radio can be a standard reference of receiving ability to compare another radios you made or you are going to make: such as 0-V-1, reflex and so on.
       Although this radio could made easily and I actually made after 15 years interval, I could have a fun. That is why I made this with a CD-R chassis. I think it is important to do measuremen or hearing, but the most fundamental is to have a fun. Thanks!
    Radio　Home