SU832525A1 - Threshold device - Google Patents

Description

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The invention relates to automation and can be used as a discriminator for the amplitude of DC signals, for example, in gas analyzer circuits for generating a control signal when exceeding or below the maximum permissible gas concentration rate.

Known threshold device discriminators amplitude current, including series-connected current generator and a tunnel.

The disadvantage of such devices is low noise immunity.

The closest in technical essence to the present invention is a threshold device comprising a tunnel diode with a series-connected resistor and an amplifier 2.

The disadvantages of such devices are low noise immunity and accuracy of the response threshold.

 The purpose of the invention is to improve the noise immunity and accuracy of the threshold.

To achieve this goal, a threshold device containing a tunnel diode with a series-connected resistor and an amplifier is inserted into the generator, a 1-phase detector

and a switch connected in parallel to the tunnel diode, the control input of which is connected to the output of the generator, and the connection point of the tunnel diode and resistor is connected to the input of the amplifier via an amplitude detector.

The drawing shows a diagram of the threshold device.

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The device contains a generator 1, an output connected to the control input of a switch 2 connected in parallel with a resistor 3 to a tunnel diode 4 connected

5 through the amplitude detector 5 to the input of the amplifier 6.

The circuit has two modes of operation; the first mode is a tunnel diode off; the second mode is a tunnel diode

0 diode On. In both modes, switch 2, controlled by generator 1, closes and opens tunnel diode 4 with the frequency specified by generator 1. Therefore, the change in voltage

Claims (1)

The tunnel diode 5 in each cycle starts from the zero level, in which state before this was not the tunnel diode. In the first mode, i.e. in the off state, the voltage drop across the tunnel diode is very small and, depending on the material from which it is made, amounts to about 50-120 mV. Thus, a pulse train arrives at the input of the amplitude detector 5, with an amplitude of 50-120 mV, and a constant voltage of the same level appears at the output of the amplitude detector. If the amplifier 6 has a dead zone of the order of 0.2–0.6 V, then the output of the amplifier will result in a signal corresponding to, for example, a zero level. In the second mode, i.e. when the tunnel diode is turned on as well. consequently, the current passing through the tunnel diode exceeded the peak value, the voltage drop across the tunnel diode abruptly increases to about 1 V. Thus, the amplitude of detector 5 in this case receives a sequence of pulses with amplitude 1 B, and a constant voltage of the same level appears at the output of the amplitude detector. This voltage is sufficient to control the amplifier 6, at the output of which a control signal appears of some level other than zero. In the proposed device, the increase in noise immunity is achieved by quantizing the input signal level using a key controlled by a generator, detecting this signal using an amplitude detector having a constant time, depending on the duration of the noise. Quantization of the input signal, which is performed with a period shorter than the interference duration, makes it possible to begin measuring the input signal each time from the zero level of the current-voltage characteristic of the tunnel diode. If the amplitude of the input signal is insufficient to turn on, but for some period of measurement, the interference will lead the tunnel diode to the second upstream branch, i.e. turns on the tunnel diode, then in the next period, the measurement of the scientific research institute provided that the interference disappeared, the circuit returns to the initial state. The appropriate choice of a constant amplitude detector makes it possible, even if a tunnel diode is turned on, when it is interfered with, to reduce the output signal from the detector to a value that is lower than the sensitivity threshold of the amplifier. Quantizing the input signal also makes it possible to increase the accuracy of the threshold, both when turned on and when the tunnel diode is turned off, because each measurement cycle starts from the zero level of the current-voltage characteristic to the first upstream branch. Thus, a threshold device containing a resistor and a key-switched tunnel diode, an amplitude detector and an amplifier virtually eliminates false alarms of the alarm and other switching devices. A threshold device comprising a tunnel diode with a series-connected resistor and an amplifier, characterized in that, in order to increase the noise immunity and accuracy of the response threshold, a generator, an amplitude detector and a switch connected to a parachute tunnel diode are inserted, the control input of which is connected to generator output. Moreover, the connection point of the tunnel diode and the resistor is connected to the input of the amplifier through an amplitude detector. Sources of information taken into account in the examination 1. Instruments and experimental technique, 5, 1963, p. 103-106. 2, Halperin E.I. et al. Pulse circuits on semiconductor devices, Soviet Radio, 1970, p. 22 (prototype).