Abstract
This paper treats a thyristor servo-amplifier applying a digital technique. The principle of this amplifier is as follows. At first, an input signal is transformed into a binary signal of four bits. By the transformed input signal, thyristors which are connected with four DC supplies of 20E0V, 21E0V, 22E0V and 23E0V respectively, are switched on or off. For example, when the input signal is three volts, i.e., (0011) volts in the binary form, the thyristors connected with the sources of 20E0V and 21E0V are switched on and the others off. By the addition of 20E0V and 21E0V, the output signal becomes 3E0V. In this manner, we can obtain the output signal of the transformed input signal times E0.
The merits of this amplifier are that the control circuit is constructed by combining simple logic circuits, and that the input vs. output relationship is nearly linear. The upper frequency depends on the frequency of the AC source which produces the DC supplies. Using the AC source of 50Hz, the upper frequency is about 10Hz. However, the step response time is very short, being approximately equal to the switching time of the thyristors.
