Comments on: Capacitors 4: Low Pass Filters

By: Anonymous

Anonymous — Mon, 30 Nov 2009 14:30:29 +0000

what is the t-filter with two capacitor and ressistance?

By: Matt

Matt — Fri, 03 Apr 2009 20:51:22 +0000

The LTSpice drawings are a bit confusing… It would be helpful if they had more clear inputs and outputs.

By: Umino

Umino — Sat, 04 Oct 2008 17:16:11 +0000

great site, but one question – can you also use that low pass filter for audio – like when you want to run a full range signal into your subwoofer amp and need to cut out the highs ? would that work with this circuit ?? and if so – wich cap and resistors should i use to have it cut at around 100hz ? PEACE – and keep up the good work

By: Sander de Groot (Asfastasdark)

Sander de Groot (Asfastasdark) — Sun, 07 Sep 2008 02:17:53 +0000

Really awesome site! But about the comment above: So basically you would want to get a decoupling capacitor of the largest value possible that fits in an enclosure? Or are there downsides to this?

By: gaussmarkov

gaussmarkov — Wed, 23 Jul 2008 21:18:02 +0000

hey Paul,

there are probably more reasons than i know. a leading constraint is the physical size of the capacitor. as cap values grow so does size. cost, too.

so folks end up balancing those things against what’s needed to get satisfactory performance. you do want your circuit in a 1590B don’t you?

and thanks for the encouraging words. they motivate me to finish writing up some new stuff.

By: Paul N.

Paul N. — Wed, 23 Jul 2008 14:30:29 +0000

I have a question. You say:

the larger the capacitor value is the more AC signal a low pass filter attenuates.

So with a power supply cap like this, wouldn’t you always want the largest cap possible, to remove more AC from the DC voltage? What are the downsides of using a capacitor too large – what else is there to take into consideration for a cap in this position?

Amazing site – I have learned so much. Thanks!!!