Microtransmitter with current stabilization. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Transmitters
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The circuit is easy to configure and manufacture; it allows you to change the frequency of the master oscillator over a wide range. The device remains operational when the supply voltage is above 1V.
The high-frequency generator is assembled using a multivibrator circuit with an inductive load. A change in the frequency of high-frequency oscillations occurs when the current flowing through transistors VT1, VT2 of type KT368 changes. When the current changes, the conductivity parameters of the transistors and their diffusion capacitances change, which allows you to vary the frequency of such a generator within a wide range without changing the frequency-setting elements-coils L1 and L2.
To increase frequency stability and the ability to control the generator in order to obtain frequency modulation, the latter is powered through a current stabilizer. The stabilizer and modulating amplifier are made on an electret microphone M1 type MKE-3, M1-B2 "Sosna" and the like.
When using standard parts, the shift in the carrier frequency when the supply voltage changes from 1,5 to 12V does not exceed 150 kHz (with an average generator frequency of 100 MHz).
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