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    • #7498
      Guenni75
      Moderator

      Hi everyone,

      some time ago I presented the “1-Transistor-Reflex-Superheterodyne Receiver” added with one AF amplifier stage for loudspeaker – now here is the more simple circuit, better known as the Boy’s Radio. This type of a pocket radio was produced from about 1959 to 1970, because the “normal” 6-transistor superhets had a high import tax to prevent production and sales problems with the home industries from Japanese lower priced pocket radios. This gap was filled quickly by small Japanese factories with these 2-transistor-reflex radios because they could be classified as “toys” and therefore with a very low tax…

      Here is one of three main variants, drawn in black. The red additions show the extensions for a real superheterodyne, see the above mentioned version (sorry for the German text…):

      With Lectron it is quite simple to build the main circuit as one unit (to prevent contact problems etc.) just like the superhet version. The reflex transformer / coil has be made as a new block. My version is a ring coil with 40:100 turns ~ 20:380 µH, any other version will fit, but an adjustment (coil with ferrit core) is recommended.

      Here are the wellknown variants with different loudspeakers:

      Perhaps it is possible to use more “normal” Lectron blocks with a similar reception success, please feel free to try and reply!

      Best,

      Günther

       

       

       

      • This topic was modified 2 weeks, 6 days ago by mwpeters75.
      • This topic was modified 2 weeks, 6 days ago by mwpeters75.
    • #7525
      LectronFan
      Participant

      Hello Günther,

      I’ve already build the two Lectron radio reflex receivers (legacy and modern transistors) following the manuals. They perform not that bad. But I believe that the circuits can be improved by using transformer coupling and better biasing. I will give this a try this weekend.
      I’m now listening to my first Philips radio from around 1975. Amazingly how selective and sensitive it still performs. It has only MW and LW reception and uses only transistors.

      Many greetings

       

      • This reply was modified 2 weeks, 3 days ago by mwpeters75. Reason: Changed font and size styling for easier reading
    • #7551
      Guenni75
      Moderator

      Hi Frank,

      I strongly believe that the Lectron reflex radio circuits could be optimized, too –  good luck!

      As you may know I am collecting old radios since more than 20 years, and I know that good adjusted / balanced / matched circuits are working so good with a few components that nobody needs integrated circuits and tons of material!

      Another aspect is the => design <= of the models, like this ones:

      or this one – with a record player and – if wanted – with a timer to wake up with Elvis Presley:

      The problem is to purchase these models – you may need a lot of money (!!!), and therefore coming back to our Boy’s Radio problem: incredible luck – I have found a Boy’s Radio with the above shown schematic and – after doing some repair – it works:

      I will come up soon with “real” powerful receivers in all categories – please be patient!

      Best,

      Günther

       

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