True Film capacitor?

JamieMcC · 4352

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Offline Paul Birkeland

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Reply #15 on: April 03, 2014, 12:02:33 PM
I would be interested in how you intend to set up this experiment.

If you put the cap and LED in series, then apply the 1.5V across them, some current will flow (briefly) to charge the cap, provided the LED is oriented correctly.  This will not, however, be dependent on the orientation of the cap (film cap). 

If you put the cap and LED in parallel, the cap will just store charge and the LED will turn off more slowly when power is interrupted. 

If you have access to a scope, it's not too tough to determine capacitor orientation:
http://jimmyauw.com/2010/04/24/observing-inner-and-outer-foil-of-some-popular-capacitors/

Paul "PB" Birkeland

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Offline JamieMcC

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Reply #16 on: April 03, 2014, 12:42:10 PM
I would be interested in how you intend to set up this experiment.

If you put the cap and LED in series, then apply the 1.5V across them, some current will flow (briefly) to charge the cap, provided the LED is oriented correctly.  This will not, however, be dependent on the orientation of the cap (film cap). 

If you put the cap and LED in parallel, the cap will just store charge and the LED will turn off more slowly when power is interrupted. 

If you have access to a scope, it's not too tough to determine capacitor orientation:
http://jimmyauw.com/2010/04/24/observing-inner-and-outer-foil-of-some-popular-capacitors/

Paul sadly if I had access to a scope I wouldn't be messing around with a micky mouse way I read about on some forum. I did try the cap with the led is series, on one try the led did light up very briefly but I could not get it to so again which ever way round I tried.

Being jumped on and having a little helper put a speedy end to my endeavours before I really got started.

From your comments and based on the fact you will have probably forgotten more than I will ever know about such things this method looks a bit of a red herring.

Shoot for the moon if you miss you will still be amongst the stars!


Offline Grainger49

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Reply #17 on: April 04, 2014, 12:09:56 AM
This might have been blown out of perspective.  If you orient the capacitor with the outer wrap toward lower voltage you get a little more noise rejection than if it is oriented the other way.

If you are in an RFI EMI rich environment it will make some difference.  In most situations it doesn't make any difference.



Offline JamieMcC

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Reply #18 on: April 04, 2014, 12:27:43 AM
This might have been blown out of perspective.  If you orient the capacitor with the outer wrap toward lower voltage you get a little more noise rejection than if it is oriented the other way.

If you are in an RFI EMI rich environment it will make some difference.  In most situations it doesn't make any difference.


Wise words indeed

Shoot for the moon if you miss you will still be amongst the stars!