1957 Five Transistor Loudspeaker Superhet

1957JuneRadioElec

Sixty years ago, the transistor radio was starting to become more and more a reality, as shown by this project in the June 1957 issue of Radio Electronics.  A year earlier, the magazine had carried plans for a four-transistor superheterodyne pocket receiver.  and had announced that “this is it,” in that the transistor could finally be used in a usable radio that could be built by the average hobbyist.  The project shown here was an update of that project, and featured one thing missing from the earlier set, namely a speaker.

1957JuneRadioElec2This set boasted loudspeaker volume on many local stations, with the sound audible as far as 10-15 feet away in a quiet room. For distant stations or for private listening, an earphone jack was provided.

The set featured five PNP transistors, with four 2N1112A’s as converter, first and second IF, and detector, and a 2N138 providing enough audio to drive the speaker.  The set was powered by a 4 volt battery.  A specific battery was mentioned, but the article noted that three N cells providing 4.5 volts would work well.

1957JuneRadioElecSchematic



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