SU1718369A1 - Periodic two-polar voltage double-sided limiter - Google Patents

Abstract

The invention relates to a pulse technique and can be used to protect radio devices from exposing their inputs to high level alternating voltage signals. The aim of the invention is to expand the field of use by introducing an adjustment of the voltage limiting level without reducing the limiting current. For this, resistor 8, 9, diode 5, source 12, input 1 and output 14 of the bus are included in the limiter containing resistors 3, 4, diode 7, transistor 11, p 13 condenser and variable resistor 10. The above set provides triggered limiting current for negative polarity signals due to the active element of transistor 11 and its interaction in the general limiter circuit, for positive polarity signals due to dynamic voltage on a capacitor 13 connected to a diode 6.1 or less. ate with 00 sa) oh

Description

The invention relates to a pulse technique and can be used to protect radio devices from exposing their inputs to high level alternating voltage signals.

The purpose of the invention is to expand the use of the possibilities of the limiter by introducing an adjustment of the voltage limiting level without reducing the limiting current.

The drawing shows the scheme of the proposed limiter.

The voltage limiter contains terminals 1 and 2 for connecting a signal source, with the second terminal being connected to the common bus, ballast resistor 3, load resistor 4, diodes 5-7, fixed resistors 8 and 9, variable resistor 10, bipolar transistor 11 pn-conduction, voltage source 12, separation capacitor 13.

The voltage limiter operates as follows.

The input voltage signal is applied to terminals 1 and 2 and through the ballast resistor 3 to the load resistor 4. The voltage limiting mode in the load is set if the voltage amplitude in the load exceeds the value of the bias voltage on diodes 5 and 6. At Through this, the diodes (low resistance) connected to direct voltage flow a current that limits the voltage in the load.

Diodes 5, 6 are connected to the common bus (diode 5 through the transition of transistor 11), therefore the current flowing through the voltage source 12 in the limiting mode is attenuated by approximately ft times (fl is the current gain of the transistor). A diode 7 protects the transistor 11 from the effect of a reverse voltage on a base-emitter junction. If diode 7 is excluded, the voltage across the emitter of transistor 11, which affects the offset of the diodes, will be 0.

Resistor 10 can adjust the threshold voltage limit. Thanks to the use of transistor 11, the power consumed by the control circuit, as well as the power consumed from the source 12

tensions are small. To build an asymmetric limiter, it is necessary to satisfy the inequalities of the resistances of resistors 8 and 9. Option

construction of the limiter with power from the source of positive polarity, but it is necessary to apply a p-n-p-conductivity transistor and change the polarity of the diodes on the reverse.

The proposed limiter has, in comparison with the known, expanded functionality due to the introduction of an adjustment to the threshold of limitation. The number of voltage sources and the current consumed from them are reduced. In the proposed limiter, there is no need to protect the voltage source against the current limit due to good isolation of the voltage source. The limiter has a low

the level of intrinsic noise in the VHF-frequency range, as it does not have Zener diodes traditionally used in such devices.

Claims (1)

Invention Formula A bilateral periodic bipolar voltage limiter containing an output bus connected through a ballast resistor to the input busbar and through a load resistor to a common busbar, two diode #, the cathode of the first diode connected to the anode of the second one, the power supply The goal is to expand the field of use by providing an adjustment to the level of limitation voltage without reducing the limiting current, two resistors, a capacitor, a variable resistor, a diode and a transistor are inserted into it, with the capacitor connected between the output bus and the cathode the first diode, the anode of which is connected to the emitter of the transistor and the anode of the input diode connected by the cathode to the base of the transistor and the output of the variable resistor, the first output of which is connected to the first pole of the power source, the second output - with the second pole of the source, with the common bus, collector of the transistor and the cathode of the second diode, and two constant resistors are connected respectively parallel to the first and second diodes.