CS256735B1 - Wiring a varkapnv power supply when changing over the paste - Google Patents

Abstract

When retuning, especially in radio receivers, over a wide frequency band, it is useful to exclude certain parts of the band. The simplest way is that the control transistor senses the output voltage for the varicap via a resistor trimmer. At a certain voltage, the operating point of the switching transistor is changed using a resistor divider. The switching transistor electrically connects the lower end of the variable resistor to ground and the voltage for the varicap, which was until then practically the same as at the upper end of the variable resistor, is now lower according to the setting of the variable resistor. The transition between the different parts of the band is fast. The circuit works as a flip-flop. The circuit can have different variants according to the adjustment of the divider by adding additional resistors.

Description

256735

The present invention addresses the need to adjust the supply of varicas used in tuned or other circuits where one or more portions of the bandwidth are to be omitted in one range of applications. Thus, in the case of smooth retuning, it is skipped at the specified voltage points of the attenuator.

So far known variations of vario feeds solve the elimination of the intermediate strip in a basic manner. Mechanically and electrically. The mechanical switching is derived from the movement of the tuning potentiometer. The electrical switching depends on the size of the tuning. Relatively complicated and costly is the solved exclusion of undesirable interband by the use of integrated circuits, such as in AO 210145. The integrated circuit works as a Schmitt flip-flop, controlled by the input voltage, which at some specific voltage switches part of the resistive decelerator to the ground to adjust the exit to fifth. The integrated circuit needs extra stabilized power supplies. Switching accuracy depends on its stability.

According to the circuitry for tuning and automatic switching of the two frequency bands, the connection has been simplified - not only the flip-flop circuit is used, but only two switching transistors.

These connections utilize that they compare the output voltage from the tuning potentiometer to a certain steady voltage. If there is a suitable difference between these voltages, the switching transistor will close. In both cases, however, the transistors are stressed in such a way that damage to the cleaner and hence the switching function can occur.

The above drawbacks and drawbacks are discarded according to the invention, the principle of which is that the variation of the resistances of the variable resistor, the lower end of which is connected to the switching transistor collector, is stressed. The switching transistor emitter coupled to ground and the base is connected to the control transistor coil along with the resistor breaker. One of the resistors is connected to the voltage of the varistor for the varnish and the second resistor is connected to the ground. The same emitter of the transistor is connected to ground. A control transistor base coupled to a resistive trimmer runner that is connected to the ground at the lower end to an upper end of the resistable resistor, to which are also fed tuning voltages provided in the tuning potentiometer to which the power supply is applied to varikapy.

By said connection, it is possible to create a multi- or more band-like arrangement of a radio receiver, especially on short and very short waves. New is the different connection and function of the components in the proposed connection. The present embodiment is more economical than previously used solutions without deteriorating quality.

Figure 1 shows the connection of the varica power supply in the simplest version. Figures 2 and 3 show other possibilities of connecting components between the switching and control transistors. Figure 4 illustrates multiple transistor connections. In a particular embodiment, according to FIG. 1, the vario voltage is taken from a customizable resistor 5, the lower end of which is connected to a switching transistor collector 3 whose emitter is connected to ground 9 and the base is connected to a collector o-control transistor 4 together with a divider a counterpart, which is a resistor 7 connected to a source voltage for a varistor 1 and a second resistor 8 to a ground 9, to which an actuator of the control transistor 4 is connected, which is connected to a runner of a resistor trim 6 which is connected to the bottom end by a ground 9 and an upper one. at the end of the upper end of the variable resistor 5, to which variable tuning voltage is applied through the tuning potentiometer area 2 from the source of the varnish 1. The engagement function according to the invention is as follows. Control transistor at a certain, minimally dependent voltage zop-no. It has a voltage divider in the collector, which operates both as a collector resistance of the control transistor, and on the other hand, which is also fed to the switching transistor base also from this divider. The voltage - emitter must not pass a certain voltage limit without the risk of damage.

The connection is suitable for all types of radio receivers to receive both modes of modulation. Although it is possible to use fine tuning with a shortwave magnifier, but this is only appropriate for the cheapest receivers. A good shortwave magnifier is only possible with inductance control.

Claims (5)

1. Switching-in power supply of variators in band switching, characterized in that the variators are connected to a variable resistance slider (5), the lower end of which is connected to the collector of the switching transistor (3), the emitter of which is connected to my (9) and base is connected to the collector of the control transistor (4) together with a resistor divider which is one resistor divider (7) connected to the supply voltage for the varcapters (1) and the other resistor divider (8) to ground (9) to which the control emitter is also connected a transistor (4), the base of which is connected to a resistor trimmer (6), the bottom end of which is connected to ground (9) and the upper end to the upper end of a variable resistor (5), which is connected over the tuning potentiometer (2) per source for varikapy (1). 2. Connection according to claim 1, characterized in that a resistance (10) is connected between the base of the switching transistor (3) and the collector of the control transistor (4j) and one resistor of the divider (7) is connected between the source voltage and the base of the switching transistor. the resistor of the divider (8) is connected between the collector of the control transistor (4) n, and the ground (9). 3. Connection according to point 1, characterized by: INVENTION that a resistor divider is wired so that one resistor of the divider (7) is connected to the power supply, the other terminal is connected to the collector of the control transistor (4) and the other resistor of the divider (8) is connected between the base of the switching transistor (3) and ground (9). 4. Connection according to claim 1, characterized in that a resistance (11) is connected between the base of the switching transistor (3) and the first and second resistors of the divider (7) -a (8) and between the collector of the control transistor (4) and the first and second. resistor of divider (7) and (8) is connected resistor (12). 5. Connection according to claim 1, characterized in that the switching transistor (3j is connected to the at least one switching transistor (3'jak actuating transistor ^(4;) is attached at least one control transistor (4 '), which are connected parallel to the upper ends of the adjustable resistors (6), which are in the bases of the control transistors (4) and further are parallel connected upper ends of resistors (7) parallel connected upper ends of resistors (7) in resistor dividers and further connected in parallel both upper ends and slider adjustable resistors (5) in collectors of switching transistors (3).