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Electronics => Electronics => Topic started by: SmAsH on August 23, 2009, 12:09:22 AM

Title: How to identify smd ceramic cap values.
Post by: SmAsH on August 23, 2009, 12:09:22 AM

Does anyone know of a way to work out the capacitance of a smd ceramic capacitor?
I have a tonne of them sitting in a tray and would like to know if anyone has a way i could identify them.

Thanks in advance,
SmAsH

Title: Re: How to identify smd ceramic cap values.
Post by: fiflak666 on August 23, 2009, 02:28:10 AM

unfortunately it isn't simple  :-\

I know only one way to find it out (as I know the only one)

You have to use multimeter able to measure capaticance (like this IMAGE (http://images.maplin.co.uk/full/gw26_sidenew.jpg)) and somehow connect it to your small capacitor (for example solder thin piceces of wire - taken from resistor - to soldering pads of capacitor)

to avoid situation like this - next time write on the tray value of capaticance (it should be done at the moment of buing - in the electronic shop)

Title: Re: How to identify smd ceramic cap values.
Post by: SmAsH on August 23, 2009, 02:31:07 AM

damn, i guess im screwed for a while then...
my old fart of a multimeter doesn't measure capacitance :P
someday ill get a new one... someday...

thanks for that fiflak666 :)

Title: Re: How to identify smd ceramic cap values.
Post by: Truckstop on August 23, 2009, 03:02:34 AM

youll need to make a cheet sheet when you measure them. i diddent even think of using them befor reading this post. heres some values i had laying around and what they measured out at...

# on cap        --    Measured value
     101       ---              100pf
       10       ---              0.01pf
     224      ---              220pf
     475     ----             47pf

Yes a good multimeter is worth its weight in gold. i have one such as the one pictured, as well as a desktop multimeter that has way too many functions...  hope the values help, they should be accurate, i tested at least 2 of each value,(2 of the ones labled 475, 4 of the ones labled 101, 3 of the 10's and 5 of the 224's. written values are average not exact.

Truckstop

Title: Re: How to identify smd ceramic cap values.
Post by: SmAsH on August 23, 2009, 03:08:07 AM

were those ones tantalum or ceramic?
i cant find any writing on my ceramic ones...

Title: Re: How to identify smd ceramic cap values.
Post by: fiflak666 on August 23, 2009, 09:34:06 AM

you won't find any writing because there are any  :P

producent doesn't put any additional signs on smd capaticor because it would change its capacity

Title: Re: How to identify smd ceramic cap values.
Post by: Truckstop on August 23, 2009, 12:39:19 PM

they are the rectangular surface mount caps. yes the smaller ones usually dont have writing on them but the larger ones do...

truckstop

Title: Re: How to identify smd ceramic cap values.
Post by: Soeren on August 23, 2009, 02:03:10 PM

Hi,

There are several ways of measuring the capacitance.

Either use a capacitance bridge (cheap) or setup an oscillator (a 555 astable would do) with Cx as the frequency determining component and measure frequency - then calculate the value of Cx.
Calibrate either with caps of a known value.