SU769711A1 - Pulse generator - Google Patents

Description

The invention relates to a pulse technique, in particular to pulse shaping circuits.

Known pulse generators for avalanche transistors, in which the storage element is a capacitor, and the transistor operating in the avalanche mode, plays the role of a switch that connects the capacitor to the load resistor at the time of arrival of the triggering pulse [1].

The disadvantage of such circuits is that the operating voltage of widespread avalanche transistors exceeds 100 V, while conventional transistors operate at voltages of 10–20 V. Thus, a separate power supply is required for pulse generators. In addition, in standby mode, a voltage equal to the supply voltage is applied to the transistor, and when an interference pulse appears at the input of the generator, a false alarm occurs.

False triggering can be without an impulse of interference, since the avalanche breakdown is statistical in nature.

Closest to the proposed pulse generator, containing an avalanche transistor with a load resistor in the emitter circuit and the storage element [2].

The disadvantage of this generator is the insufficient amplitude of the output pulses.

The purpose of the invention is to increase the amplitude 5 of the output pulses.

This goal is achieved by the fact that in the pulse generator containing an avalanche transistor with a load resistor in the emitter circuit and a storage element 10, the specified storage element is made in the form of series-connected inductors and choppers, and the avalanche transistor is connected in parallel to the chopper or inductor15.

In FIG. 1 and 2 depict two embodiments of a pulse generator.

The current generator 1 sets the current I through the inductor 2 and the normally closed contacts of the chopper 3 (the direction of the current is shown by the arrow). The transistor 4 operating in the avalanche mode is connected in parallel to the chopper 3 (Fig. 1) or the inductor 2 (Fig. 2), the load resistor 5 is connected to the emitter circuit of the transistor 4.

The pulse generator operates as follows.

We assume that the resistances of the inductor 2 coil and chopper 3 (in the closed state) are equal to zero, then there will be zero voltage on the avalanche transistor 4. With the arrival of the trigger pulse to the chopper 3 at the connection point of the chopper 3 with the inductor 2 voltage occurs

U = -L di _t Δ7

--— L-dt Δί where L is the inductance value;

Δί is the breaker on time;

Δ / = - / - current change during the shutdown time (we believe that the current has completely stopped).

Thus,

If / = 100 mA,

Δί = 1 μs,

L = 2 MGn, then V »200 V.

This voltage is quite enough for the operation of all the most often used in avalanche mode transistors (GT 338, KT603, KT312, P426), etc.).

As breakers, you can use lamps, transistors, fully controllable transistors and other devices.

Such schemes allow the use of low-voltage power supplies used in conventional transistor devices. The absence of a constant high voltage improves safety. In addition, the generator does not operate from an interference signal if, in terms of parameters, this signal is not close to the start pulse. The circuit is also protected from statistical fluctuations in the elements of the device, i.e. In the standby state, zero voltage is applied to the avalanche transistor.

Claims (2)

Claim 1. A pulse generator containing an avalanche transistor with a load resistor 15 in the emitter circuit and a storage element, characterized in that, in order to increase the amplitude of the output pulses, the storage element is made in the form of series-connected inductance coils and a chopper, and the avalanche transistor is connected in parallel with the chopper. 2. The pulse generator in π. 1, characterized in that the avalanche trans 25 torus connected in parallel ’inductor. ..........