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Old 23rd September 2002, 02:28 PM   #1
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Default Questions for active crossover

My first electronic project - to build a 3-way active XO.

- I got & studied schematic for both powersupply & XO. OK.
- I got op amps (OPA2134)

Can I ask stupid questions?

- What are orange drop caps? (I found them at Apex Jr for cheap & in values I want, appx 33nF) Are they suitable for this app? Can you recommend other capacitors & source?
- I'm thinking of using registor array / network to allow me to play with different XO frequencies. They're 2% tolerance, 14-DIP package (7 registors) sold at Digi-key & Mouser. Any problem using them?
- How should I connect the ground from the power supply? to signal ground? not connected?

Thanks,

Duc
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Old 23rd September 2002, 05:22 PM   #2
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Orange Drop is the trade name for some of the early mylar caps, made by Sprague.... over the years it just kind of became part of the language. They were all epoxy dipped in orange resin, flame proof and in their day really quality stuff. The ones you are looking at are surplus and I suspect pretty good value for the money, this based on past experience with the supplier, not on experience with the caps you mention.



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Old 23rd September 2002, 07:45 PM   #3
Electrons are yellow and more is better!
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Philips (BC Components) makes also nice looking orange polyester caps of medium performance.
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Old 23rd September 2002, 08:10 PM   #4
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Default polyester caps of medium performance.

Wrong again. Use poypropylene which are easily available. Try Digikey

http://www.digikey.com/

Orange Drop Polypropylenes

http://www.sbelectronics.com/sbe.htm


All about capacitors

http://www.capacitors.com/pickcap/pickcap.htm

Sin Bin by Sundown,

Ren

P.S. polyester
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Old 23rd September 2002, 09:55 PM   #5
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16 pin resistor networks and ZIF sockets work great.
Used them on the Threshold PCX. Get good sockets, tho.

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Old 24th September 2002, 07:04 AM   #6
Electrons are yellow and more is better!
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Quote:
Originally posted by Nelson Pass
.... Get good sockets, tho.

This is very important in the long run. Cheap sockets are cheap! You wil get bad contact (too low contact pressure) and also the IC's can simple fall off!

Strong recommendation to you who use sockets: Use gold plated, "tulip"-model. The hole has four springs (like a tulip) and this kind of socket is very reliable. It's easy to push in the IC but hard (very hard sometimes) to pull out.
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Old 24th September 2002, 07:17 AM   #7
Electrons are yellow and more is better!
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Default Re: polyester caps of medium performance.

Quote:
Originally posted by Ren Hoek
Wrong again. Use poypropylene which are easily available. Try Digikey
P.S. polyester
I did only comment that Philips has "orange drops" but they are of polyester. We discussed in an another thread about caps and the conclusion was that importance caps are so great compared to semiconductors. Of course polyester is "medium" (not bad at all!) in many senses and if you of some particular reason want a better type, then choose it.

If you have the opportunity to measure each cap, polyester can do just fine in a active filter in the audio band. The main problem is often that they aren't available in so many values and also the tolerance isn't so good but the stability aren't so bad. Personally if prefer polypropulene where it's possible. The advantage of polyster is that they can be made small, much smaller than polypropulene.
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Old 24th September 2002, 11:53 AM   #8
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Default Polyester caps

Stacked film types, from Wima, Rifa, Panasonic or Siemens are usually quite good. They are small and cheap enough so you can measure each or make parallel/series combos to get to less than 1% values sometimes.

They should be the best value option for those 1uF types on Rod Elliot's circuit, in my opinion.

If you go to other certainly better types, like polypropylene or polystyrene types, price and size will be an issue.


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Old 24th September 2002, 02:10 PM   #9
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Thanks for all the suggestions. Ask for good DIP sockets, where can I get those? Are stuff by Apex Jr & Digikey good enough? As for voltage rating, I should use appx 50V or less since most likely it will be below 2v, right?

How should I connect the ground wire for the power supply? to the signal wire or let it float?

Thanks,

Duc

Hopefully I'll report results back shortly.
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