I need help with a power supply, I used a ceramic capacitor my question is Why do we usually use them? To filter I first used a electrolit cap and then the ceramic one but I really don't get why...

Question

I need help with a power supply, I used a ceramic capacitor my question is Why do we usually use them?  To filter I first used a electrolit cap and then the ceramic one but I really don't get why...

anonymous · Answer

The electrolytic capacitor acts sort of like a diode or a fuse for voltage. It blocks DC in one direction to a certain point, then it pops. Just see a couple data sheets. There are a ton of pros and cons for each.

anonymous · Answer

I'll make a quick comment on this, but be nice since I am new here. The typical power supply I see will use both Electrolytic and Ceramic Capacitors. The Electro is for bulk storage, it smooths out the big spikes that come out of the bridge rectifier. The Cer is for reducing ripple. What it lacks in capacity, it makes up for in speed, charging and discharging much quicker than the Electro. It will smooth out the high frequency stuff.

anonymous · Answer

(Electrolytic) In powersupplies, they are also necessary for ac/dc coupling. You can't use ceramic for this.

radar · Answer

The electrolytic provides filtering for the ripple from the output of the rectifier, if halfwave it is a 60 Hz ripple, fullwave a 120 Hz (assuming 60Hz line) For higher frequencies such as RF the electrolytics are not a good bypass thus the ceramics are for bypassing  locally generated RF, IF, hash etc. The inherent inductance of a electrolytics, lead length etc. makes for poor bypassing (in spite of less reactance.