SU1539983A1 - Switching device - Google Patents

Abstract

The invention can be used to periodically turn on incandescent bulbs in car direction indicators. The purpose of the invention is to increase the reliability in the event of a short circuit (CC) of the lamps and to enhance the flashing effect of their operation. The switching device contains transistors 1,6,7,8,10, resistors 4,11,13,16, a generator of 9 pulses, a capacitor 12, a diode 14, a zener diode 15. Connecting the base transistor 10 to the collector of transistor 7 and to the supply bus 3 via Resistor 11 and capacitor 12, respectively, and the emitter to supply buses 2 and 3 through resistor 16 and Zener diode 15, respectively, allow the short circuit mode to be built up according to the duration of the output current and accelerate the heating of the filaments of the load lamps 5. 1 Il.

Description

The invention relates to a pulse technique and a mock up to be used to periodically turn on incandescent lamps in car turn indicators.

The purpose of the invention is to increase the reliability during short circuit (short circuit) of the lamps due to the detuning of the short circuit mode from the norm for the duration of the load current flow and to enhance the flashing effect of the load lamps by accelerating the heating of their filaments.

The drawing shows a circuit diagram of the device.

The switching device comprises a first transistor 1, an emitter and

the collector of which is connected to the first 2 and second 3 supply lines through the first resistor 4 and load 5 (lamps), respectively, the second transistor 6, the emitter gap - the collector of which is connected between the base and collector of transistor 1, and the base is connected to buses 2 and 3 - lecture-emitter gaps of the third 7 and fourth 8 transistors, respectively, whose inputs are connected to the resistor 4 and the output of the generator 9 pulses, the fifth transistor 10, the collector of which is connected to the base of the transistor 7, a serial RC circuit from resistor 1 1 and capacitor 12, shunted by the second resistor 13, diode 14 and sta-i

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bilitron 15. The base of transistor 10 is connected to the collector of transistor 7 and bus 3, respectively, through a resistor 11 and a capacitor 12, the emitter of transistor 10 is connected to buses 2 and 3 via a third resistor 16 and a zener diode 15, respectively, and a diode 1 is turned on according to transistor 7 collector circuit.

Resistor 17 is used to adjust the load current. Resistors 18-23 provide a transistor operation mode. In the load circuit 5 can be included node 24 control.

The device works as follows.

The generator 9 generates rectangular pulses with a frequency of 1-2 Hz, the duty cycle of which is equal to two. These pulses are amplified by transistors 8.6 and 1, and through node 24 they are fed to lamps 5 of direction indicators. With the passage of a current pulse on a resistor 4, a voltage drop is proportional to the current through the lamps 5. This voltage through resistors 17 and 21 is applied to the transition baza-emitter of transistor 7. When the load current reaches the specified value, the voltage across the base-to-emitter transition transistor 7 becomes sufficient to open it. Transistor 7 goes into linear mode and with its collector-emitter junction the diode 14 shunts resistor 18, thereby regulating the base current of transistor 6 and, accordingly, the emitter current of transistor 1 so that the voltage drop across the resistor 4 and the corresponding current loads 5 are maintained at a predetermined level. As the filaments of the lamps 5 heat up, their resistance increases and the output current begins to decrease to the rated current of the lamp 5. The voltage drop across resistor 4 decreases, transistor 7 closes, and transistors 6 and 1 go into saturation region. With the passage of the next pulse, the cycle repeats.

At the same time, transistor 7, diode 14 together with transistor 10, zener diode 15, resistors 11,13,16 and 20 and capacitor 12 form a high-speed trigger protection against short-circuit in the load 5. Parameters in0

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The switching circuit (resistors 11, 13, capacitor 12) is chosen so that during the time that transistor 7 is in the open state, i.e. during the pulse duration of the output current, the voltage on the capacitor 12 reaches only half the voltage of the opening threshold of the transistor 10, which is set by the zener diode 15. At the end of the duration of the output pulse, the capacitor 12 is discharged through the resistor 13 to zero.

Claims (1)

With a short circuit in the load, the voltage on the capacitor 12 reaches the opening threshold of the transistor 10, which leads to the avalanche process of the transition of the transistors 10 and 7 into the saturation mode and the locking of the transistors 6 and 1. This state of the transistors 1,6,7 and 10 is maintained until clear. power supply voltage. Invention Formula The switching device containing the first transistor, the emitter and collector of which is connected to the first and second supply lines through the first resistor and load, respectively, the second transistor, the emitter-collector gap of which is connected between the base and collector of the first transistor, and the base is connected to the first and the second power bus through the collector-emitter gaps of the third and fourth transistors, respectively, whose inputs are connected to the first resistor and the output of the pulse generator, respectively, fifth a transistor whose collector is connected to the base of the third transistor; lamps, the base of the fifth transistor is connected to the collector of the third transistor and the second power supply bus, respectively, through a resistor and a capacitor of a series RC circuit, the emitter of the fifth transistor is connected to the first The second and second supply lines through the third resistor and the zener diode respectively, and the diode is connected in accordance with the third transistor into its collector circuit.