SU1552357A1 - Monostable multivibrator - Google Patents

Abstract

The invention can be used in the circuits of automation and computing. The goal is to increase the stability of the duration of the pulse being formed - by introducing keys 12, 13 and new electrical connections between functional elements: a trigger 1, a driving capacitor 2, transistors 3, 7, a zener diode 4, resistors 5, 6, 8, into the standby multivibrator with a single transistor 9, a current-supplying resistor 10 and a threshold element 11. 1 sludge.

Description

The invention relates to a pulse technique and can be used in automation and computer circuits.

The purpose of the invention is to increase the stability of the duration of the formed pulp.

The drawing shows a schematic diagram of a waiting multivibrator. ! · The multivibrator contains a trigger 1, the first input and output of which are connected respectively to the input and output buses of the waiting multivibrator, a timing capacitor 2, the first [output of which is connected to a common bus of the power source, the first current source, made on the first transistor 3, zener diode 4 and the first resistor 5, a reference voltage source made on the reference resistor 6 and a second current source containing a second transistor 7, a zener diode 4 and a second resistor 8, a discharge transistor 9, the emitter of which is connected to a common power supply bus, and the base with the first output of the current-setting resistor 10, a threshold element 11, the first input of which is connected to the output of the second current source, the second input to the second output of the time-setting capacitor 2, and the output to the second input of trigger 1, the first key 12 whose control input is connected to the first output of trigger 1, the first output to the output of the first current source, the second output is connected to the second output of the timing capacitor 2, the second key 13, the control input of which is connected to the second output of trigger 1, the first output d is connected to the second terminal of timing capacitor 2, a second output - to the second terminal of the reference resistor 6 is connected to the collector of whom also the discharge transistor 9, a second terminal voltage driving resistor 10 is connected "to the bus power source.

Multivibrator works as follows.

In the initial state of the device, trigger 1 occupies a position in which a low logic level signal acts on its first output, and a high logic level signal acts on its second output. The signal of a low logic level, acting on the first output, leads to the opening of the key 12, and the signal of a high logic level at the second output leads to the closure of the key 13. The voltage at the timing capacitor 2 is equal to the collector-emitter junction voltage of the saturated transistor 9. Saturation cut of the transistor 9 is set by the current-sensing resistor 10 from the power supply bus. The reference voltage U _o is created at the reference resistor 6 connected in series and the emitter-collector junction of the saturated transistor 9 with the current 1 _{0 of the} second current source (zener diode 4, transistor 7, resistor 8) and is% = i ₀ ^R i> ⁺ V and ₄ -IE & 7 where I = —------ current of the second source ° ^to 8 current nickel;

U _H is the saturation voltage of the transistor 9;

U ₄ is the voltage at the zener diode 4;

- transition voltage emitter - the base of the transistor 7.

When a generated pulse is applied to the first input of trigger 1, trigger 1 moves to a new position, at which a signal of a high logic level acts at its first output, and a low signal at its second output. The key 12 is closed by the signals of a high logical level, received from the first output of the trigger 1 to the control input of the key 12. The key 13 is then opened by a signal of a low logical level. The capacitor 2 begins to be charged by the current of the first current source (zener diode 4, transistor 3, resistor 5). The charge of the capacitor 2 occurs with a constant slope not from the zero value, but from the voltage value equal to the saturation voltage U _{H of} transistor 9. When the voltage reaches the reference U _o (U ₂ = U _o = I _o R _fe + U _H ), an output occurs at the output of the threshold element 11, which returns the trigger 1 at the second input to its initial state. In this case, the key 12 is opened, and the key 13 is closed, the timing capacitor .2 is discharged through the closed key 13 and the transistor 9. Since the voltage at the terminals of the closed key 13 is practically zero, the voltage across the capacitor 2 in the initial state is equal to the saturation voltage of the transistor 9 .

The pulse duration / generated on the output bus is determined by the following expression:

r- = (Tso zUid-C = = =

Provided that Ι | .αρ = 1 ₀ , get? = R _fc -C, where T-uar “ ^t ok the first current source;

C is the capacity of the timing capacitor 2.

Thus, in the standby multivibrator due to the exclusion of the instability of the discharge transistor 9, a high stability of the duration of the Formed pulse is ensured. The elimination of instability is achieved by the inclusion of a saturated transistor 9 both in the circuit of the reference voltage source and through a controlled key in the discharge circuit of the timing capacitor.

Claims (1)

Claim A waiting multivibrator containing a trigger, the first input and output of which is connected respectively to the input and output buses, a timing capacitor, the first output of which is connected to the common bus of the power source, the first current source, made on the first transistor, zener diode, and the first resistor, a reference voltage source made on a reference resistor and a second current source containing a second transistor, a zener diode and a second resistor, a discharge transistor, the emitter of which is connected to a common bus of the power source, and the base is with the first output of the current-setting resistor, a threshold element, the first input of which is connected to the output of the second current source, the second input with the second output of the timing capacitor, and the output with the second trigger input 20, characterized in that, in order to increase the stability of the duration, The generated pulse, the first and second keys are inserted into it, the control inputs of which 25 are connected respectively to the first and second outputs of the trigger, the first output of the first key is connected to the output of the first current source, the second output to the second output om timer 30 of the capacitor and with the first terminal of the second switch, the second terminal of which is connected to the collector of the discharge transistor and with the reference resistor, the second terminal of the lead-in resistor is connected to the bus of the power source.