Block diagram of the voltage source, showing the design of the ±15 V channels. The design for the −5 V channel is slightly different since a voltage divider between the -filter and the voltage controller is necessary. For the channel, however, the input voltage for the voltage controller is directly taken from the battery.
Circuit diagram of the sine generator, mainly consisting of a Wien-bridge-oscillator (Ref. 23), a part to stabilize the amplitude, and an amplifier.
Circuit diagram of the power amplifier. In the upper part, the initial sinusoidal signal is retained unchanged, whereas it is inverted in the lower part by OpAmp . OpAmp provides a 6 V dc-offset. The two 180°-phase-shifted sines are then applied to the OpAmps and , addressing two identical push-pull stages. The large capacitor at the upper output corrects the dc-offset voltage between the two outputs of the design.
Optional wiring of the power amplifier to increase the maximum current. Only the upper part of the entire design is shown. The power OpAmp is supplied by its own output voltage, taken from behind the filter. In this realization, the 12 V battery voltage is only used for the start-up of the OpAmp and as soon as the output voltage is higher it takes over. Obviously, the output transistors still have to be supplied by the battery.
Circuit diagram of the voltage controller for the output. The reference voltage and its wiring are explained in Sec. ???. For more details, see text.
Circuit diagram of the voltage controller for the −15 V output. The functional principle is equivalent to the positive voltage controller (see Sec. ???).
Circuit diagram of the reference voltage wiring. The reference voltage VRE310 (Ref. 30) provides 10 V output voltage, which is adjusted for each controller. The gray-highlighted parts label the voltage controllers, which are not completely shown. The characteristics of the resistors used for converting the reference voltage and for the voltage dividers in the feedback are reflected in the output voltage and should therefore have a low temperature drift.
Long-term stability of the output channel. The measurement was performed in a temperature-stabilized enclosure with a load of . The time slice between two measurements was 7 s.
(a) Histogram and (b) Allan-deviation of the output voltage shown in Fig. 8. The dashed line in (a) is a Gaussian distribution fitted to the data, yielding an FWHM of .
Noise level of the output. In the operation region of the voltage controller, the noise level is slightly higher. The small peaks do not originate from the voltage source, but are external distortions.
Temperature dependency of the output voltage. The dashed line is a linear fit which determines the temperature coefficient to .
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