Capacitor Size Matter?

[stealth17]

Does the physical size of a capacitor matter? Like a tiny 16v 1000uf just as good as a large 16v 1000uf?

 

[audioguru2]

A larger new capacitor has a better ripple-current rating.
If the capacitor is used as the rectifier filter in a high current power supply, It will have a high ripple voltage across it because its charging and discharging currents are high. A small capacitor will overheat and fail. You might need to use a large capacitor with a higher voltage rating to find one with a high ripple-current rating.
Large old capacitors have about the same ripple-current ratings as small new ones, so don't just select a larger size.

 

[stealth17]

A larger new capacitor has a better ripple-current rating.
If the capacitor is used as the rectifier filter in a high current power supply, It will have a high ripple voltage across it because its charging and discharging currents are high. A small capacitor will overheat and fail. You might need to use a large capacitor with a higher voltage rating to find one with a high ripple-current rating.
Large old capacitors have about the same ripple-current ratings as small new ones, so don't just select a larger size.

cool, thanks. Ive read that its not a real good idea in most cases to go over 150% original capacitance. The voltage doesn seem to matter either. Like I can use a 25v cap in place of a 10v cap without problems. Also Ive read that the low-ESR caps are the ones rated for 105c (usually).

Sound all up to par?

 

[prateeksikka]

hi audioguru !
sorry for the interruption but i would say that a surge in the supply would be a more appropriate word than ripple.
Although i agree with u that a large cap has higher rating for surges.

 

[audioguru2]

Hi Prateek,
Large value capacitors are usually used as filters following a full-wave rectifier in high current equipment. Surges are infrequent but ripple current occurs continuousy, on every half-cycle of the mains. Because the load current is high, the capacitor's ripple current is also high which overheats small capacitors.

 

[prateeksikka]

So should we go for large caps specially in filters.
In all ckts i have seen they are generally  the largest components.
A huge giant of a small value. It looks as a pole in a small circuit.
;D