[sdiy] Typical ESR of different capacitors

Richie Burnett rburnett at richieburnett.co.uk
Sat Sep 4 13:24:25 CEST 2010

Also it's worth keeping in mind that the effective series resistance of 
aluminium electrolytics varies considerably with:

1. Temperature
2. Age

All those switch-mode power supplies that end their life repeatedly power 
cycling with blinking power LEDs are usually due to dried up output 
electrolytics.  When old and cold ESR is at it's maximum.  So if you really 
do need to get that old computer PSU up and running, try gently heating it 
with a hair dryer to warm the electrolytics before applying power.  It 
usually raises the temperature (lowering ESR) enough to get the supply to 
start up in a stable manner.  Once it's up and running the internal heating 
of the ESR from ripple current will usually keep the supply going until it 
is switched off!

I used to work in power electronics and have seen many a design go unstable 
at low temperature, or fail early in the life cycle due to bad choice of 
electrolytics or the dreaded Taiwanese capacitor plague.


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