electrolytic capacitor and polarity of AC

[PG1995]

Hi

Please help me to understand how an electrolytic capacitor work.

1: Please have a look here; you would find my question there. Thank you.

2: Can we use electrolytic capacitor with DC?

Regards
PG

 

[mister_rf]

Have you try first to read something about electrolytic capacitors? :grin:

Most electrolytic capacitors are polarized and require one of the electrodes to be positive relative to the other; they may catastrophically fail if voltage is reversed. This is because a reverse-bias voltage above 1 to 1.5 V[2][3][4] will destroy the center layer of dielectric material via electrochemical reduction (see redox reactions). Following the loss of the dielectric material, the capacitor will short circuit, and with sufficient short circuit current, the electrolyte will rapidly heat up and either leak or cause the capacitor to burst, often in a spectacularly dramatic fashion.

Electrolytic capacitor - Wikipedia, the free encyclopedia

---------- Post added at 00:51 ---------- Previous post was at 00:47 ----------

Polarized capacitors are mainly used in DC circuits.
https://www.cde.com/catalogs/AEappGUIDE.pdf

 

[alexan_e]

Also note in the above link that there are non polarized electrolitics intended to be used for AC

However there are special non-polarized electrolytic capacitors for AC use

Special capacitors designed for AC operation are available, usually referred to as "non-polarized" or "NP" types. In these, full-thickness oxide layers are formed on both the aluminum foil strips prior to assembly. On the alternate halves of the AC cycles, one of the foil strips acts as a blocking diode, preventing reverse current from damaging the electrolyte of the other one.

one of the uses of these capacitors is in the crossover of loudspeakers, in the low pass section of the crossover for the woofer in a second order LC filter where a high capacitance is needed (as shown Second Order Passive Crossovers, 12 dB per Octave )

You can use two electrolytic in series (+ to + or - to -) to get a non polarized of half the capacitance of a single cap but a non-polarized electrolytic is better
diyAudio - How to make non-polarized electrolytic cap?

Alex

 

[PG1995]

Thank you, Mr. RF, Alex.

Actually I was wrong in a way. Because electrolytic capacitor is in fact used with DC. For AC, there are special kind of electrolytic capacitors.

I have read that 'regular' capacitor can store very little amount of charge in comparison to a electrolytic capacitor and that's the reason they are preferred over 'regular' or 'normal' capacitors. Is this really so? Please let me know. Thank you.

 

[alexan_e]

In general the electrolytic capacitor characteristics are worse that other types (ceramic, tantalum, polyester etc) but it has the advantage of high capacity and with low cost so it is used in applications that need a high capacitance.
The choice of capacitor type depends on the application type and specifications so there will be exceptions where different types may be used.

Alex

 

[PG1995]

Once again, thanks, Alex.

1: I think in the linked image, the caps on the left side of the red 'line' are electrolytics, and on the right regular/normal ones, please correct me if I'm wrong:
https://img641.imageshack.us/img641/7758/capshn.jpg

2: In the linked image on the left side of ICs you have transistors:
https://img818.imageshack.us/img818/3044/semiconductors.jpg

Are ICs (integrated circuits) pre-fabricated circuits which work as a unit in a circuit in which they are used?

Thank you for your time and help.

Regards
PG

 

[alexan_e]

The left side black and blue are electrolytic but the other two are mylar capacitors (the wrapped ones).
In the right side the orange is polyester (MKT), the brown and blue are ceramic and the green is usually mylar too

In general the IC is like a circuit containing different components packed in a small case, it is usually used as part of more complex circuits.
A chip case can contain anything (not necessarily an integrated circuit), it can be an array of transistors, or a compete integrated circuit or just an optocoupler or a microcontroller or an eeprom or ram etc
You can even find single mosfets in 8 pin IC case so only the datasheet can explain with detail what is the purpose of each IC.

Alex

---------- Post added at 00:23 ---------- Previous post was at 00:04 ----------

You can take a look at

CapSite 2009
Capacitors

and you will definitely like this


Alex

 

[PG1995]

I was watching this video on UTube and thought it might be useful to someone like me who stumble onto this thread:

I didn't know that ICs also contain resistors and capacitors; I thought they contains in themselves only semiconductor components - i.e. diodes and transistors.

 

[PG1995]

Thanks a lot, Alex, for your reply.


1: Do ICs ever contain inductors?


2: Computer processors are also ICs. In the video in my previous post the presenter compares the size of an IC and its equilant circuit in 'normal' form. How large would an equivalent circuit of a modern day processor (IC), let's say Intel P4, be?


3: Almost every computer processor has its Hz rating. Nowadays processors come in GHz ratings. Wht does this frequency rating mean? A computer works in digital mode, i.e. on and off state. So, does this Hz rating tell how many times an invidual transistor can turn on and off without damaging itself? I don't want to get into technical details of this. So, please it involves some very technical details then you can skip this query. Thanks.


Many thanks for all your help.


Regards
PG

 

[alexan_e]

I'm afraid I can't answer your questions, I'm more experienced into practical circuit applications so I don't know much about the internal structure and manufacturing of IC.

About the computer processors I only know that they are rated to run up to a specific speed where the operation of the cpu is guaranteed but they can usually run with higher speed and that is exactly what overclocking is.
The cpu will not be damaged with overclocking as long as the chip temperature is maintained in the device specified limits but the cpu will generate errors above a certain speed which is different for each production chip.

Alex