SU425324A1 - Asymmetric Multivibrator - Google Patents

Description

one

The invention relates to radio engineering and can be used as a generator of rectangular pulses.

Known asymmetric multivibrator containing transistors conductivity pnp and pn-type, time specifies the L C-chain, collector and oazovye resistors. However, such an asymmetrical multivibrator does not provide a soft excitation and cannot generate oscillations with a long period.

The purpose of the invention is to increase the oscillation period and provide a soft excitation of an asymmetrical multivibrator.

For this, between the negative pole of the power source and the emitter of an n-fj-n type transistor, an additional series circuit comprising an inductance and a semiconductor diode is included.

The drawing shows a circuit diagram of the proposed asymmetric multivibrator.

Asymmetric multivibrator contains a transistor of conductivity 1 p- / g-r type and a transistor of conductivity 2 pn-p type, time specifies a C-chain consisting of capacitor 3 and resistor 4, resistors 5, 6, 7. The emitter of transistor 2 is connected with the negative pole of the power source through a series-connected coil (inductance) 8 and diode 9.

When the power is turned on, transistor 2 through the resistor 5 receives the input current and opens. Since the collector current of transistor 2 is the input current of transistor 1, the latter also opens and saturates. The capacitor 3 through the coil 8, diode 9, the emitter junction - the base of the transistor 2, the collector-emitter junction of the transistor 1 is charged from the power source. If the inductance of the coil 8 is selected from the condition of the oscillatory charge of the capacitor 3, then the latter is charged approximately equal to E, where E is the voltage of the power source. In this case, the base of the emitter of the transistor 2 is shifted in the opposite direction, and the transistor 2 is closed, which leads to the locking of the transistor 1.

The collector voltage L-sepia of transistor 1 is summed with the voltage of the charged capacitor 3 in such a way that a voltage of approximately 3 is applied to the base of transistor 2.

From a voltage level equal to: E, capacitor 3 is discharged through resistors 4 and 5 until the voltage at the base of transistor 2 becomes equal to the voltage across its emitter. Transistor 2 opens, and

the entire cycle of operation is repeated.

Thus, the inclusion in the emitter circuit of transistor 2 coil 8 leads to the forced closing of transistor 2, regardless of the ratio of the resistance values of the collector resistor 6 and the base resistor 5, which increases the stability of the circuit and makes it less sensitive to the variation of the transistors. An increase in the voltage at the base of transistor 2 at the time of locking transistor 1 to the level of WE increases the oscillation period of the multivibrator with a constant value of the time constant of the C-chain. Diode 9 prevents breakdown of the base-emitter junction of transistor 2 during its reverse bias.

The subject of the invention

Asymmetrical multivibrator, containing p- / g-p conductive transistors and n-p - n types, master / C-chain time, collector and base resistors, characterized in that, in order to increase the non-oscillation period and provide of the soft excitation mode, between the negative pole of the power source and the emitter of a pnp type transistor, a further series is connected, containing

inductance and semiconductor diode.