SU949778A1 - Current converter in periods between pulses - Google Patents

Description

(54) CURRENT TRANSMITTER DURING BETWEEN PULSE

The invention relates to a pulse technique and can be used in the formation of pulses, the time between which is directly proportional to the magnitude of the controlled direct current.

Known Converter made on the blocking generator, in which, the source of the converted current by one output through a resistor and the primary winding of the pulse transformer is connected to the collector of the input transistor, the base and the emitter in which are connected to each other through a pulse transformer 1.

The disadvantages of this device are the inverse relationship between the magnitude of the input current and the time between pulses, as well as the complexity of the design and the presence of several power sources.

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Also known current transducer in the period between pulses, containing the first and second transistors of different types of conductivity, a capacitor and a source of converted current 2.

The disadvantages of the known device are the complexity of the design and the need to have an additional power source.

The purpose of the invention is to simplify the device.

This goal is achieved by the fact that a current transformer in the period between pulses, containing first and second transistors of different conductivity types, a capacitor and a source of converted current, is additionally introduced a pulse transformer, the beginning and end of the first winding of which are connected to the base and collector of the first transistor, respectively, in parallel the current source includes a capacitor, 15 one of the terminals of which is connected to the collector of the first transistor, and the other with a common length, the second winding of the pulse transformer on roan connected to the collector of the second transistor, whose base is connected to the common schinoy ° and the end of the second winding and the emitter terminals of both transistors are connected to each other directly, wherein the load is connected to the terminals of the third winding of the pulse transformer.

FIG. 1 shows the electrical circuit of the device; in fig. 2 is a graph of the pause time between pulses and the magnitude of the input current.

The device is a pulse transformer 1, the first winding 2 of which is connected to the base and the collector of the first transistor 3, a capacitor 5 connected to the collector of the first transistor 3 and a common bus is connected in parallel with the current source 4, the beginning of the second winding 6 is connected to the collector of the second transistor 7, the base of which is connected to the rim by the bus and the end of the second winding, the emitter terminals of the transistors 3 and 7 are connected to each other, and the load is connected to the terminals of the third winding 8 of the pulse transformer 1.

Consideration of the operation of the device will begin with a relaxation recharge of capacitor 5 in the steady state at a constant current.

After switching to the saturation mode, the transistors 3 and 7 become unmanaged elements, and the nature of the voltage change on the capacitor 5, the base of the transistor 3 and the collector of the transistor 7 is determined only by the external circuit elements. At this time, a pause between the pulses and discharge of the capacitor 4 occurs. As the capacitor 4 discharges, the current through the emitter of transistor 3 and the collector of transistor 7 decreases (the current through the collector flows because the voltage between the emitter and base is much higher than between the emitter and the collector of the saturated transistor 7).

When reducing the current of the emitters of transistors 3 and 7 to the value at which the voltage drop across the active resistance of the winding b becomes less than the voltage drop between the emitter and the base of the transistor 7, the transistor 7 changes from saturation to active mode. The gain of the feedback loop through the windings of the pulse transformer becomes greater than one, and therefore an avalanche-like process develops, after which transistors 3 and 7 do not conduct current for the duration of the pulse, defined mainly by the parameters of a pulse transformer (transistor 3 locked up

the negative voltage generated on the winding 2 of the pulse transformer 1 due to the self-induced EMF). While the transistors are in the locked state, capacitor 5 is charged from source 4,

and the larger the current from source 4, the more capacitor 5 will charge to a higher voltage. The discharge time increases, which increases the pause between pulses in proportion to the current.

The proposed converter does not require power sources for its operation, which is very important when used in devices with galvanic isolation, the source of the converted current can have a large internal resistance,

Connect the proposed converter through a high-resistance resistor directly to high-voltage sources of 1000 V and more when used in a low-voltage transistor circuit.

Claims (2)

1.Doronkin EF Transistor pulse generators. M., “Holy, 1968, p. 175176. 2. USSR author's certificate No. 396813, cl. H 03 K 3/02, 1971 (prototype). ISf / f