Any advantages/pitfalls with CS-CAP capacitors for hobby electronics? - Page 1
Forum section: electronics / beginners

author: gildasd
author_rank: Frequent Contributor
timestamp: December 26, 2015, 08:10:06 pm
content: CS-CAP or Conductive Polymer Aluminum Solid Capacitor,For normal hobbyist stuff (not radio or high end sound), is there any advantage?Do we need to modify any calculation over normal electrolytic capacitors?

author: mrpackethead
author_rank: Super Contributor
timestamp: December 26, 2015, 08:13:19 pm
content: Polymer type capacitors have several advantages over a normal Aluminum Electrolytic Capacitor. The polymer electrolyte has higher conductivity than the liquid electrolyte used in standard capacitors, resulting in lower ESR. This permits a single polymer type capacitor to replace several aluminum electrolytic type capacitors, resulting in reduced board space and total number of components on the board. Since the polymer is a solid, it also gives longer life, not following the classic Arrhenius formula. Instead of doubling life with every 10°C drop in temperature, the lifetime will be 10 times longer for every 20°C decrease in temperature.Yes, they are a little more expensive, but for circuits where having low ESR is importnat ( Power Supplies ), they can make a big difference!

author: gildasd
author_rank: Frequent Contributor
timestamp: December 26, 2015, 08:21:17 pm
content: Quote from: mrpackethead on December 26, 2015, 08:13:19 pmSo you read Digi Key toohttp://www.digikey.com/us/en/ph/nichicon/AlumCondPolymer.htmlI just happened to get some instead of electrolytics and wondered if they were any major pitfalls.Will save them for power supply filtering and as pull caps on the ICL7660 negative voltage generator.Would they be good for using as pull capacitors on a LM7660?

author: mrpackethead
author_rank: Super Contributor
timestamp: December 26, 2015, 08:23:14 pm
content: Quote from: blueskull on December 26, 2015, 08:16:17 pmYes, but longer lifetime, and less ripple. ( potentially ).. Everything in engineering is a compromise.

author: gildasd
author_rank: Frequent Contributor
timestamp: December 26, 2015, 09:07:24 pm
content: Quote from: blueskull on December 26, 2015, 08:39:21 pmOn a more amateur level, these are some example uses:1) On a generic 12V 1Amp wall wart supply,a standard 1000µF electrolytic cap before a 7809.Then a 470µF electrolytic after after it.Taking the edge (or spike) off the ripple so that it is usable to feed op amps and the such without leakage.2) As 10 µF pull caps on ICL7660.3) As simple RC filter (think 100 Ohms, 47µF) before supplying DC parts in the 1V to 9V range.And other boring basic stuff.

author: gildasd
author_rank: Frequent Contributor
timestamp: December 26, 2015, 09:37:19 pm
content: Quote from: blueskull on December 26, 2015, 09:14:30 pmThanks for the answer.For 1, my methodology is to get a rough estimate with T=R*CThen to prod around that value with a varying caps while watching the effect on an oscilloscope.I start low (lets say 470µF in this case), and go up: 1000µF, 1500µF etc.A certain point the gain in "cleanness" is not noticeable compared to the value before, I stop at this value.What you are saying is that I should add a load test AFTER to see if my values are stable?I feel like I'm explaining how to sharpen sticks to MIT staff... This is very crude...

author: mrpackethead
author_rank: Super Contributor
timestamp: December 26, 2015, 09:53:34 pm
content: Quotein deed. IN fact i was working on a design just the other day, using a Micrcel Buck converter, where additional ripple is actually designed into the compensation network.