Only to inform, no questions.


Mod Note: Removed link (it was also it was in not in English

 

Mod Note: Removed link (it was also it was in not in English

Source:
"Radio" № 11, 1983 y
page 55, D. Priimak, "Simplest sound generator".
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Below are simulations of circuits from source.

Q1 and Q2 are germanium:

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Only Q1 is germanium:

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Voltage converter + sound alarm:

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RL oscillator:

 

Really interesting An oscillator with the tuned element generating a voltage controlled by mechanical resonance. Very impressive.