Electro caps orientation

Frequently asked questions on capacitor types, ratings, brands, use and abuse.

Electro caps orientation

Postby Duckman » 26 May 2009, 00:56

I always read about "correct" electro caps orientation when you are designing a circuit, I mean, all positives (or negatives) leads pointing to the same PCB side. But, honestly, 99% of the stompboxes (standard or boutique) and/or photos I see, comfirm to my eyes that this is not a "golden rule". I wanna know if somebody has noticed or experimented a real improvement or even a perceptible difference between circuits that have "correct" or "incorrect" caps orientation.

Thanks to all!
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Re: Electro caps orientation

Postby bajaman » 26 May 2009, 01:26

polarised electrolytic capacitors should always be connected with their positive terminals to the most positive dc voltage potential points when placing them in the circuit. For example - when using a polarised electrolytic capacitor as a coupling capacitor from a npn emitter, or n channel jfet source, being run as a buffer from a positive dc supply voltage, this point will usually be at approximately half the supply voltage (+4.5v dc when using a +9v dc supply), and so you should connect the positive terminal of the electrolytic capacitor to this point. The other terminal usually connects to a resistor (or potentiometer volume control etc.) which has it's other terminal; connected to ground and so is at zero dc potential.

Failure to observe the correct polarity will result in non linear distortion (not good!!) and possible destruction of the electrolytics dielectric (explosion if run from very high voltage :slap: )

Hope this helps :wink:
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Re: Electro caps orientation

Postby Duckman » 26 May 2009, 01:47

Tkx, Bajaman! Your posts are always very usefull, and one of my actual proyects are based in your info about Musicman Stingray pre. But, about the electros, I'm talking about phisical orientation, not electrical orientation. Any sonical or ellectrical advantage by placing all electros facing the same side? If not, I think I can save a lot of traces! Got the piont?

Big Thanks!! :thumbsup :thumbsup
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Re: Electro caps orientation

Postby bajaman » 26 May 2009, 02:12

Any sonical or electrical advantage by placing all electros facing the same side?

No - none whatsoever :wink:
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Re: Electro caps orientation

Postby JiM » 26 May 2009, 09:37

Duckman wrote:Any sonical or ellectrical advantage by placing all electros facing the same side?

The only advantage is from a manufacturing point of view : it's less error-prone, and easier to check.
It might also be an unintentionnal side effect of all negative leads being connected to the same ground strip. :wink:
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Re: Electro caps orientation

Postby Duckman » 27 May 2009, 03:35

Well, since my level of manufacture are very low...[smilie=a_bluesmile.gif] what a relief to me! I found myself few times re-tracing and re-re-tracing designs only to keep electro caps "well" oriented. Any way, it's not an error in the end and, in certain way, looks neat, like those guys who place components very simetrically (only Antelope come to my mind now) but, this is another theme.

Tkx JiM!
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