Switching Power Supply 0-10A 0-25V

[Sceadwian]

What do you think a filter capacitor does? Just sit there in the circuit to look good? =-) They absorb energy and feed it to the circuit during the low portion of the AC cycle. If you have a lot of ripple or it's a single phase AC mains supply there's quiet a bit of current going through the filter caps.

 

[bbjk]

yeah i knew that... but where is the current actually lost? the capactior stores charge during the low part of the AC then feeds it back during the high part...

 

[Sceadwian]

Capacitors aren't perfect. They have an ESR rating, they heat like any physical object does when current passes through it.

 

[bbjk]

also, smanches, i had a look at pwm using a 555 and i understand it somewhat... but its hard to see exactly how it is varried in the curcuit... something to do with the op-amp?

 

[bbjk]

Capacitors aren't perfect. They have an ESR rating, they heat like any physical object does when current passes through it.

ok... thx, still seems like a lot though...