how can a polarized capacitor be reversed charged in astable multivibrator, as it is stated that capacitors reverse charge their polarized during operation of astable multivibrator....please help me im a learner

 

as it is stated that capacitors reverse charge their polarized during operation of astable multivibrator

Where did you get that idea? They charge and discharge, but that is not the same as reversing.

 

Post a schematic if you want further explanation.

 

The capacitors reverse-charge to only +0.7V minus the +0.1V of the saturated transistor's collector driving it.

 

Did you measure the voltage across the capacitor, or the voltage from one side of it to the other? I did the latter, and it goes from 1V to 4V, not going negative.

 

The capacitors alternately charge in reverse to a small voltage:
In my simulation in post #4, the negative end of the transistor reaches +0.7V at the base of one transistor, and the positive end is at the almost 0V of the other saturated transistor collector, when the circuit switches causing the capacitor to charge with normal polarity by the 100k collector resistor.

 

We are both right. Depends on the circuit. This circuit, modified from the example astable multivibrator circuit that comes with LTSPCE, does not have that problem. The voltage shown is across C1.

 

The capacitors reverse-charge to only +0.7V minus the +0.1V of the saturated transistor's collector driving it.

thank you for your answer, but will it not destroy the polarized capacitor?

 

Applying a reverse polarity voltage, or a voltage exceeding the maximum rated working voltage of as little as 1 or 1.5 volts, can destroy the dielectric and thus the capacitor. The failure of electrolytic capacitors can be hazardous, resulting in an explosion or fire.

https://en.m.wikipedia.org › wiki
Electrolytic capacitor - Wikipedia

 

Vishay says: Up to 1.5V of reverse voltage is permissible:
https://www.vishay.com/docs/25001/alucapsintroroederstein.pdf

The simple multivibrator circuit produces a reverse voltage of only 0.7V.

 

how can a polarized capacitor be reversed charged in astable multivibrator

Post a schematic so we know what you're referring to.

 

In this common and simple circuit the capacitors charge with correct polarity to about 5.3V and charge with reverse polarity to about 0.7V.

 

Not only can a capacitor be discharged to a lower voltage, at least some of them can be charged in the reverse direction, at least to some extent. There will be a fair amount of leakage current, which can often lead to overheating, and, if the power is not limited adequately, lead to failure and an explosion. So a reverse charge of some amount is entirely possible, BUT there is no reason to think that the performance will be as the specifications for the correct polarity.