Philips PM 5131 Gerätehandbuch Seite 11

1.4. OPERATING PRINCIPLE (see Fig. 1., block diagram)
The oscillator of the function generator comprises the switched integrator and the peak detector (comparator).
The controlled current source of the d.c. control section generates the charging current for the integrator. At
the integrator output a linear voltage ramp is fed to the peak detector. When reaching the reference voltage the
detector reverses the charging current of the integrator resulting in integration in the opposite direction.
Integration down is performed until reaching the negative reference level of the peak detector, which again
reverses the current of the switched integrator. As both reference levels are symmetrical with respect to earth,
a zero symmetrical triangular wave is generated at the output of the integrator. The duty cycle of this wave
is 1:1.
A squarewave signal of the peak detector is fed via the TTL buffer to the TTL OUT socket.
The stabilized power supply provides the d.c. voltages for the circuitries.