Service Data; Circuit Description; Simplified Diagram Of The Oscillator - Philips PM 5125 Manual

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SERVICE DATA
Circuit description
A. OSCILLATOR (See Figs. 8, 9, 10 and 27)
The sine wave oscillator used in this instrument is a phase-shift oscillator
consisting mainly of three amplifier stages TS22, TS25 and TS29, which'
are coupled by means of the emitter followers TS23—TS24, TS26—TS27
and TS30—TS21 respectively.
Two identical frequency control circuits have been used. The fi rst one
is connected between the collector and the emitter of TS22 and consists,
of the capacitors C21...C27 and the resistors R24—Rh—R25. The second
one is connected between the collector and the emitter of T525 and
consists of the capacitors C28...C34 and the resistors R30—Rlrr—R31.
These networks provide each aphase-shift of 90° at the oscillation
frequency, fo.
.,a~
Fig. 8. Simplified diagram of the oscillator