SU731590A1 - Electronic switch - Google Patents

Description

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The device relates to the field of electrical engineering and can be used to switch signals at the input of analog-to-digital converters.

Electronic switches are known for switching analog signals with transformer control circuits 1. In these devices, the transformer core is re-magnetized along a private hysteresis loop, the magnetic permeability of which is less than that at the ultimate hysteresis, which leads to an increase in the size of the transformer.

An electronic key is known, comprising 15 control transistor, two power sources, a limiting resistor, a control unit, a transformer, to the secondary windings of which the control inputs of transistor switches are connected. With this, the emitter of the control transistor and the second output of the first power source are connected to a common busbar, the collector of the control transistor is connected to the first 25 output of the first power supply through the primary winding of the transformer, and through the limiting resistor to the first output of the second power supply. The base of the control transistor is connected to the output of the control unit 2.30

The key's pitch is the increased power dissipation, which leads to low efficiency of the device.

The purpose of the invention is to reduce power dissipation.

To do this, an electronic switch containing a control transistor, two power sources, a limiting resistor, a control unit, a transformer, to the secondary windings of which the control inputs of the transistor switches are connected, the emitter of the control transistor and the second output of the first power source are connected to a common bus, the collector of the control transistor through the primary winding of the transformer is connected to the first output of the first power source, and through the limiting resistor to the first output of the second source ika power, the base of the control transistor is connected to the output of the control unit, introduced an additional transistor, the conductivity of which is opposite to the conduction of the control transistor. In this case, the emitter of the additional transistor and its collector are connected to the first output of the first power source and to the second output of the second power source, respectively, and the base of this transistor is connected to the output of the control unit.

FIG. 1 shows the scheme of the electronic key.

It contains the first 1 and second 2 power sources, the control unit 3, the transformer primary winding 4, the control transistor 5, the auxiliary transistor 6, the limiting resistor 7, the transformer secondary windings 8, 9, the transistor switches 10, 11, and the damping diode 12.

FIG. 2 shows a hysteresis loop of a transformer core.

The principle of the device is as follows.

In the initial state, the control transistor 5, the auxiliary transistor 6 and the switches 10, are closed. The core of the transformer is located at point a (Fig. 2). The switching pulse from control unit 3 opens the control transistor 5, the collector current of which, flowing through the primary winding 4, remagnetes the transformer core at point b. The voltage pulse on the secondary windings 8, 9 of the transformer opens the transistor switches 10, AND, commuting analog signals. At the end of the turn-on impulse, the control transistor 5 and the switches 10, AND are closed, and in the control unit 3, a turn-off impulse is generated that opens the auxiliary transistor 6, the collector current of which peremagnetizes the core of the transformer at point c. In this case, in the secondary windings 8, 9, the voltage pulses are so polar that the switches 10, 11 remain closed. At the end of the switching off pulse, the additional transistor 6 is closed, the current through the primary winding is stopped, and the core of the transformer returns to the initial state - to point a (Fig. 2).

The power at the limiting resistor is dissipated only during the operation of the control pulses (on, off), and the magnitude of this power decreases in proportion to the duty cycle of the control pulses.

Consequently, the required power of the power sources and the collector current of the main transistor are reduced, which increases the efficiency of the device.

Claims (2)

1. Patent of the secondary school № 3048715, NKI 307-282, 27.06.60. 2. US patent number 3466462, NCI 307-240, 09.09.69.