Multivibrators

1. What are Logic Multivibrators?‌

A ‌logical multivibrator‌ is an oscillator built on logic gate circuits (such as NAND gates, NOR gates, etc.) to generate square waves or pulse signals. Its core feature is to use the switching characteristics of logic devices to achieve automatic switching of circuit states and form periodic oscillation output.

 

According to stability, it can be divided into three categories:

‌Astable‌: no stable state, continuous output of square waves (such as clock signals);

‌Monostable‌: there is a stable state, and a single pulse is output only when externally triggered;

‌Bistable‌: there are two stable states, and a trigger signal is required to switch (such as a trigger).

 

2. What are the ‌Circuit Features of Logic Multivibrators?‌

It is usually composed of logic gates (such as TTL and CMOS gate circuits), resistors, capacitors, and other components, and the charging and discharging process is controlled by a feedback loop to achieve oscillation.

 

For example: two cross-coupled logic gates (such as NAND gates) constitute the core oscillation unit, and the frequency is adjusted in conjunction with the RC timing circuit.

 

3. Positioning in Logic Devices

It belongs to the sequential circuit branch of logic IC, and together with flip-flops, one-shots, etc., it constitutes the timing and control module of the digital system.

 

Attention should be paid to level compatibility (such as TTL/CMOS level) and timing parameters (such as propagation delay and setup/hold time) to ensure system stability.

 

4. What are Logic Multivibrators Used for?

Clock Signal Source: Provide reference clock for microcontrollers and counters;

Pulse Shaping and Delay: Monostable mode is used for precise delay control after event triggering;

State Storage: Bistable mode realizes binary data storage (such as SR latch).

 

5. Association of Key Logic Elements

Logic gates (74 series gate circuits), flip-flops (such as D/J-K flip-flops), and timing elements (RC networks) are commonly used in construction;

 

The design needs to consider power consumption, noise tolerance, and driving capability, especially in mixed-voltage systems.

 

Note: The logic multivibrator is a basic module of digital circuits. Its design needs to take into account the coordination of logic device characteristics and analog timing elements.