[sdiy] Typical ESR of different capacitors

[Simon Brouwer]

  Op 2-9-2010 23:48, Antti Huovilainen schreef:
> On Thu, 2 Sep 2010, Simon Brouwer wrote:
>
>>> It's been hard / impossible to find good information online about 
>>> the topic as manufacturers tend to only list ESR for their low-ESR 
>>> capacitor models.
>>
>> That is not my experience. For example, the first cheap 10uF 
>> aluminium electrolytic I find on the Farnell site has this datasheet: 
>> http://www.farnell.com/datasheets/14936.pdf
>
> That would be a low-esr capacitor (it even says "Low impedance" in the 
> datasheet). The question was about non low-ESR capacitors like the 
> ones many of us might have lying around.
>
>> Wrt your question about dissipation factor and ESR, see 
>> http://wiki.xtronics.com/index.php/Capacitors_and_ESR#Dissipation_Factor
>
> Too bad the claims on that page don't actually match with manufacturer 
> datasheets for low ESR capacitors at least.
>
> It's obvious once you do the calculation using 100 kHz as the 
> frequency where even DF of 1.0 would result in absurdly low ESR values 
> for larger caps. Using 120 Hz gives much too high ESR on the other 
> hand (1.8 ohms vs the actual 0.35 ohms for Panasonic FC series 100 uF 
> / 25V)

You're comparing dissipation factor at 120 Hz to ESR at 100 kHz. DF also 
includes leakage losses.

> Up to tens of uF, consider a ceramic capacitor. They have very low 
> ESR. For higher capacitance, look for low-ESR aluminium.
>
> Highest valued ceramic I can get locally is 1.0 uF and they're rather 
> costly compared to the capacitance.

Just an example:

http://nl.farnell.com/multicomp/mcca000542/mlcc-08055v-10v-10uf/dp/1759421

Try to find similar in aluminium, let alone tantalum, at lower cost.

-- 
Vriendelijke groet,
Simon Brouwer.

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