14.1 V 14.1 V
+14.1 V00 -14.1 V
14.1 V 14.1 V
230/120 V AC
Compensation Amplifier Based on High-Precision Reference Signal Creates Pure 230 V (or 120 V) AC Source
■ ■■ ■
■Low-Distortion Reference Signal GeneratorThe waveform of the signal detected at the S 2 winding of the power transformer (see
Fig. 1) is used by a highly precise Zener diode circuit to generate a square waveform.
A newly developed 50/60 Hz bandpass filter and band-stop filter are then applied to
the waveform. The filter frequency is
switched in sync with the input
frequency, for automatic 50 Hz and
60 Hz support. By routing the signal
through another bandpass filter, a
low-distortion sine wave (reference
signal) is created that is not
dependent on the input voltage. ■ ■■ ■
■Superior Waveform Compensating PowerWhen the input voltage is 220 V (110 V), the voltage at the secondary side of the transformer will
also be 220 V (110 V). To bring this to 230 V (120 V), 10 volts must be added, as shown in Figure (a).
Conversely, if the input is 240 V (130 V), 10 volts must be subtracted to yield 230 V (120 V), as
shown in Figure (b). (As the figures show, in actual operation, the peak value of 10 V, namely
14.1 V, is added or subtracted.) The sine wave (e
i) synchronized to the input frequency and the
output voltage (e o) are
compared, and for any
excessive or missing
component, a compen-
sation waveform up to a
maximum of ±10 V (peak
value ±14.1 V) is gener-
ated and imposed on the
output voltage. Conse-
quently, for an input volt-
age range of 200-253 V
AC (108-132 V AC) at the
rated load of 1200 VA
(1000 VA), the output
voltage is kept cons tant
at 230 V ±2% (120 V ±2
%), with a maximum dis-
tortion ratio of 0.22%.
These values demon-
strate the outstanding
ability of the PS-1210.
Reference Signal Generator Block Diagram
Excellent Current Capability
The power amplifier which performs waveform compensation uses the current feedback
principle for excellent high-frequency phase characteristics and operation stability.
This is combined with the MCS+ circuit renowned for superior performance and sound
quality. The output stage uses 20 transistors rated for a maximum current of 15 amperes.
These devices are connected in a parallel complementary push-pull arrangement
which boasts a rated output current of 5.2 A (8.3 A) and an instantaneous peak current
(inrush current) rating of 60 A (120 A). This demonstrates the excellent current capability
of the PS-1210.
bAssembly with waveform compensation amplifier for addition/subtraction, output stage
with 20 parallel push-pull power transistors mounted to two large heat sinks, waveform
compensation amplifier, etc.
Note: The explanation is for the 230 V AC version of the PS-1210. Figures in brackets refer to the 120 V AC version.
Waveform Shaping Principle of PS-1210
(a) If power source voltage is
lower than 230 V (120 V),
addition is performed(b) If power source voltage is higher
than 230 V (120 V), subtraction is
The photograph shows the
230 V version.
■ ■ ■ ■
■ Assembly with reference signal generator and other circuitry