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Recent content by richard6798

  1. R

    Substitution of old germanium transistors in radio circuits

    Well, I'm going by this: "Here are two unusual transistor types, marked AEI TR1A and TR2A. What is really odd about them, apart from the fact that I cannot find them in any data book (and I have a *lot* of data books on germanium transistors) is that they use the black-painted 'top hat'...
  2. R

    Substitution of old germanium transistors in radio circuits

    Actually, that TR1A designation is probably an Ediswan XA101. Type Designator: XA101 Material of transistor: Ge Polarity: PNP Maximum collector power dissipation (Pc), W: 0.12 Maximum collector-base voltage |Ucb|, V: 20 Maximum collector-emitter voltage |Uce|, V: 0 Maximum emitter-base...
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    Substitution of old germanium transistors in radio circuits

    I've been looking for what type of detection is involved, and now I see: The circuit given involves Plate Detection or, I think, known also as Anode Bend Detection. Of which the Infinite Impedance Detector is a variant. Knowing this I can read up on what has been published. Although the circuit...
  4. R

    Substitution of old germanium transistors in radio circuits

    I see now that the configuration is "Audion Configuration". I think that is a reflex design (but might not be). An NPN version sees TR1 as BC548, R1 as 100K, phone impedance about 64 Ohms, C3 10uF, C4 100nF and and Battery Volts 1.5V.
  5. R

    Substitution of old germanium transistors in radio circuits

    Hi. Originally, I think Phone would have been a single earpiece of LOW impedance. "Trionic" set owners might know. :c) I've got the Trionic PCB's but not the components. I'm just wondering whether to use a crystal earpiece, or get a pair of low impedance headphones. - - - Updated - - - I've...
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    Substitution of old germanium transistors in radio circuits

    The original transistor would be a PNP germanium type (AEI - TR1A). I think an RF type, or at least designated that I believe (by Tri-ang). Original battery voltage was 9V. If you were to substitute that germanium PNP transistor with a modern PNP silicon transistor, what transistor would you...
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