Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
Well electrolytic is a class of capacitor and ceramic is a type of Electrolyte
most capacitors (to increase their capacity) use some form of Electrolyte to increase the capacity.
ceramic is a type of Electrolyte and is fairly stable and accruate (but COG/NPO are better). The problem is they are only avaialbe at low capacitance.
COG upto 1n
and ceramic upto 220nF
that is where the electrolytic capacitors come in. The Electrolyte used in them exibits a higher electric charge storing capability and thus you can get upto the Farads in capacitnace. This comes at the price of stability and freq range (due to strays within them) as well as they start to become polorised (ie can only support voltage in one direction)
As to the interchanagbility IF the capacitance is the same you can always go Electrolytic to ceramic, the otehr way around you have to be careful there is reversing of voltage (IE you cannot use an electrolytic as a DC-blocking cap)
Let me try to clairify: A capacitor consists of two or more metal plates seperated by an insulating dielectric. Current flows into and out of the capacitor as it is being charged and discharged, so it can pass AC but blocks DC. Some dielectrics produce more capacitance than others, depending on the dielectric constant. Air has a dielectric constant of 1, an insulator with a constant of 5 would produce 5 times the capacitance.
The DC leakage thru a capacitor depends on it's construction. Most film and ceramic capacitors have such low leakage that you don't need to worry about it. electrolytic capacitors have high leakage (microamps) but you can still use them for DC blocking as long as you take account of the leakage.
The temperature stability of a capacitor depends mostly on the dielectric. Film capacitors are most stable, polystyrene being good. Ceramic capacitors have a wide range of stabilities, ranging from NPO (negative, positive zero) which is most stable to Z5U which is usually given as +80, -20 % tolerance.
The dielectric in electrolytic capacitors is an oxide on the metal plate. Contact to the dielectric on the other side of the metal is made by the electrolyte. The oxide dielectric is built up in a process called "forming". A limited current is allowed to flow thru the capacitor and as the oxide builds up, the voltage is increased. If the capacitor is unused for a long time, the dielectric deteriorates but can be re-formed. If the capacitor is old and not re-formed, it can blow up in a power supply.
It's not really so - BUT, large capacitors are generally used for low frequencies, and small capacitors for high frequencies. Large capacitors are generally electrolytic (for size and cost reasons), and small capacitors are non-electrolytic (of which ceramic is one type).
So in practice the rather crude generalisation is pretty well correct!.
There's no reason you can't get high value ceramics, IF you were prepared to pay the massive price, and you don't mind your capacitors the size of wardrobes and small houses! :lol:
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
what npo means?
