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 Post subject: Need Help Identifing Parameters
PostPosted: Feb Fri 14, 2020 2:01 pm 
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Joined: Feb Fri 14, 2020 1:46 pm
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Hey all,

I'm new here, but an old EET from years back (haven't worked in the discipline in decades).

Anyway, I'm trying to get the audio crossover to work on my 1964 Pontiac Catalina (switches front/both/rear speakers). The NP capacitor is definitely bad. Reading it, I know it's 16-25 Volts/Non-Polarized. What is not clear to me is the ufd. I'm guessing 2ufd. Please see attached.

Thoughts?

Thanks,

Ron


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 Post subject: Re: Need Help Identifing Parameters
PostPosted: Feb Fri 14, 2020 2:32 pm 
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Normally they put the capacitance and the rating in the same line on most caps like that. But as small as it is, it may be only 2 uF. To see if that is plausible, what is the impedance of your speakers? The DC resistance will be lower than the actual impedance but maybe only by an ohm or two. You can use one of the online crossover calculators knowing the impedance to see if 2 uF gives you a plausible crossover point for your tweeter. This is assuming it is a tweeter crossover cap and not for midranges.

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 Post subject: Re: Need Help Identifing Parameters
PostPosted: Feb Fri 14, 2020 3:29 pm 
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Speakers are 10 ohm each.

If you expect me to remember my formulas from 35 years ago, your memory is WAY better than mine lol Can someone give me a formula or point me to a site that calculates?


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 Post subject: Re: Need Help Identifing Parameters
PostPosted: Feb Fri 14, 2020 3:35 pm 
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I just pulled up one of those online calculators..... got it! Looks like 2 ufd is correct

Thank you!!


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 Post subject: Re: Need Help Identifing Parameters
PostPosted: Feb Fri 14, 2020 3:59 pm 
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Maybe 16 uF @ 25VDC?

I never saw a cap that was rated 16 to 25 Volts.

Rich


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 Post subject: Re: Need Help Identifing Parameters
PostPosted: Feb Fri 14, 2020 4:10 pm 
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Rich, W3HWJ wrote:
Maybe 16 uF @ 25VDC?

I never saw a cap that was rated 16 to 25 Volts.

Rich

That is my best guess also

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 Post subject: Re: Need Help Identifing Parameters
PostPosted: Feb Fri 14, 2020 9:11 pm 
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Location: Mountains of Mourne. Ireland.
Pontiac 1963-64 Catalina, Bonneville, Grand Prix
AM-FM PB radio 12V
Delco 983945 1963 (shown)
Delco 984078 1964

Image
https://sites.google.com/site/identifyi ... /pontiac-1


"Delco" capacitor 7275751 can most likely be seen in Sams AR-24 (auto radio) under GENERAL MOTORS 984078

fyi... Tempest installation notes, 1968 - - can be found in Accessories, Section 15
http://thefirstgensite.com/html/68smi.html

Greg.


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 Post subject: Re: Need Help Identifing Parameters
PostPosted: Feb Fri 14, 2020 10:39 pm 
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I will also go with 16mf @ 25 volts, the schematic will tell the truth.

DM


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 Post subject: Re: Need Help Identifing Parameters
PostPosted: Feb Sat 15, 2020 9:54 pm 
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Location: Long Island NY
16-uF at 25 volts. The '2' in the circle is a proprietary identification code, probably the factory, line, or shift that made the cap for GM.

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 Post subject: Re: Need Help Identifing Parameters
PostPosted: Feb Sat 15, 2020 9:57 pm 
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Ain't rocket science; 16 uF, 25 volts, Non Polarized.

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 Post subject: Re: Need Help Identifing Parameters
PostPosted: Feb Sun 16, 2020 12:07 am 
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Yep, I'll jump on the pile-up, 16 uF @ 25 volts.

If it turns out that that's the wrong value, YOU CAME TO THE WRONG PLACE. :wink:

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 Post subject: Re: Need Help Identifing Parameters
PostPosted: Feb Sun 16, 2020 2:37 am 
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Don't forget the "NP" almost certainly means "non-polar".

-Chuck


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 Post subject: Re: Need Help Identifing Parameters
PostPosted: Feb Sun 16, 2020 4:16 am 
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The "2" in the circle was a proprietary trade mark of the Sprague corporation.


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 Post subject: Re: Need Help Identifing Parameters
PostPosted: Feb Sun 16, 2020 4:49 am 
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For the Majority of us Who isn't Rocket Scientists the determination was well done, should I say it was a 5-4-3-2-1 Blastoff. :mrgreen:

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 Post subject: Re: Need Help Identifing Parameters
PostPosted: Feb Tue 18, 2020 2:56 am 
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Location: Norfolk, VA
Bob E. wrote:
The "2" in the circle was a proprietary trade mark of the Sprague corporation.



+1 - Sprague had trademarks on a "2" in a Circle, Square, and Triangle.

Circle - 0509306 (renewal 0908981)
Triangle - 0754020
Square - 1104684

The square was most commonly seen on plate-style tantalum capacitors (look like ceramic discs, but with polarity and uF values) I've seen the triangle only once - on a snubber cap made by Sprague. All are now expired/dead trademarks..... :|

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