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Old 26th December 2015, 07:48 PM   #1
tazzo is offline tazzo  United Kingdom
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Join Date: Mar 2012
Default Looking For Some Help

First of all I'm a beginner who does not claim to have experience in DIY and am looking for some help.

I replaced cheap generic 50V film capacitors in the signal path with 800V ones which I bought because they were cheap, now i'm wondering if I have messed up and should have gone for lower volts.

Secondly I am looking for some help on how to read an ESR rating from a datasheet, for example, what would the ESR be for 1000uf@35V for Elna Silmic 2. The datasheet is below, I need a bit of help on how to determine the ESR ratings.

Datasheet (PDF) - http://www.hificollective.co.uk/site...lna_silmic.pdf

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Old 26th December 2015, 08:54 PM   #2
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Location: Carlisle, England
Using a higher voltage cap is ok.
Murton-Pike Systems PCBCAD51 pcb design software. http://www.murtonpikesystems.co.uk
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Old 26th December 2015, 09:10 PM   #3
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Location: Dallas (but I am not a Texan!)
Many (most?) capacitor datasheets do not specify ESR, except for caps designed for switching power supply or other HF use.

You can approximate the ESR using the Dissipation Factor (also called "tangent of loss factor") that is listed on the datasheet. Note that this is specified at one frequency (120Hz in this datasheet).

ESR = DF * Xc, or DF * 2 * pi * f * C, where f is the frequency (120Hz) and C is the capacitance (1000uF = .001 Farad). 0.075 ohms if I did the math right in this case...

Here is a paper showing the calculation:


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Old 29th December 2015, 02:43 PM   #4
tazzo is offline tazzo  United Kingdom
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Join Date: Mar 2012
Thanks for all the help, I have bought an ESR meter now and have been taking readings. Funnily the Elna Silmic caps, two of them are reading around 2000uf for 1000uf Caps, could they be damaged?

Also the ESR reading taken with an ESR meter are variable for the same caps, one minute they can read 0.8ohms, and other times 0.5ohms although they generally read the same value for the same cap Is this normal, can the readings be variable?

One last thing, the readings for one or two of the Silmic 2 caps read 0.5oms most of the time, even though it is supposed to be 0.075 as specified above (which I checked out myself), can the ESR reading be ever so slightly higher (0.8ohms) or lower (0.5ohms) as I have been reading or do you think they may be damaged?

Again thanks for all the help.
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Old 29th December 2015, 03:36 PM   #5
tazzo is offline tazzo  United Kingdom
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Join Date: Mar 2012
When I mean "damage" as referred t in my post above, I am checking the caps for damage from soldering them into the circuit board, as I heated up the leads for too long trying to get them through the PCB and I am worried I may have damaged them.
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Old 29th December 2015, 03:41 PM   #6
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Always use a solder sucker to remove solder from the pc board before attempting to insert the cap lead.
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Old 29th December 2015, 08:26 PM   #7
tazzo is offline tazzo  United Kingdom
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Join Date: Mar 2012
I did that, but the holes where a fraction too small. I am now thinking that the ESR meter may be faulty...
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