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Old 20th September 2012, 02:48 PM   #421
klewis is offline klewis  United States
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Quote:
Originally Posted by dirkwright View Post
Well, maybe so. I looked up the parts kindly mentioned by 1audio but they didn't seem right to me. I went digging through the Mouser catalog and I'm still not sure if I found the right part. There's a lot of things I don't know. I guess sometimes solder solves the unknown just as good.
Mouser Catalog, look at the label on the side of the page, your looking for "Rectangular Connectors" At top of page look for "3M .100" x .100" Pin Strip Header" Mouser part no. 517-6111tg 40 pin straight, just cut to length. The female part I use is the CHG -2020 "3m headers & wire housings". It's a double row socket that you punch down the wiring into then with a small screw driver fold over two metal tabs to retain the wire (I'm sure their is some special tool for this). Look for the CHG series the CHG 10 series are single row, and the 20 series are double row.
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Old 20th September 2012, 04:58 PM   #422
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I just received my rack mount chassis from Par-metal. Wow! This is far far better than the Hammond box I bought before. The quality of the series 14 is outstanding! They are getting all of my business from now on.

Also, since Victor didn't supply a template for a face plate for his oscillators, and the fact that I'd more than likely NOT get the holes in the right place, I'm going to modify his board. I'm going to take off the pot, the LED, and the two RCA jacks and use different ones directly on the front panel and wired to the board remotely.
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Old 20th September 2012, 05:05 PM   #423
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Template is on his eBay listing. However, your idea gives a lot of flexibility.
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Old 20th September 2012, 05:32 PM   #424
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Quote:
Originally Posted by dennismiller55 View Post
Template is on his eBay listing. However, your idea gives a lot of flexibility.
Yeah, I have difficulty doing layout to 0.5mm. I didn't see that before obviously.

Speaking of which, what would be the best way to provide a balanced output for this oscillator? Galvanic isolation is also desirable, so I'd have to use a transformer for that. I'm going to try out the mixed feedback method as described by Lundahl:
http://www.lundahl.se/pdf/ovrigt/feedbck.pdf

Walt Jung got good results using this method, as described in his op amp book.
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Old 20th September 2012, 07:12 PM   #425
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Balanced output simply requires equal impedances to ground. It does not require signal balance to ground, such as a center-tapped xfmr. If you feed the oscillator with a transformer isolated power supply and do not bond the common, you have a balanced output. It is floating, but balanced nontheless. I then wire a + and - terminal for signal (floating/balanced) and then a grounded shield wire.

All that is suggested then is whatever you are driving be a differential input with equal resistances to ground for a DC reference. I rarely have good noise results with a floating system; it should be grounded somewhere. Just make sure this ground reference provides equal impedance to ground, and that the shield is grounded in at least one spot (ideally the input side in this case, near where the reference bond exists).

This is somewhat backwards from the ideal condition, where the source is referenced, and the shield grounded at the source. But careful layout and wiring can result in the 'backward' style being just as noise free.
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Old 21st September 2012, 01:02 PM   #426
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OK thanks. I didn't explain very well. I want both single ended and balanced outputs, with the balanced galvanically isolated, available at the same time.
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Old 21st September 2012, 05:48 PM   #427
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Does the quality of the potentiometer matter for Victor's oscillator? I managed to get it out, but what ever solder he used is really difficult to work with. It won't come off very well with solder wick and I don't have a suction bulb handy. I don't like this solder at all. It's a pain in the @ss basically. Anyway, the pot is a really cheap carbon 10k. I wonder if a better pot would improve anything? Lower noise maybe?
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Old 21st September 2012, 06:48 PM   #428
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Quote:
Does the quality of the potentiometer matter for Victor's oscillator?
A true audiophile never stops thinking that anything must matter, eh?

As seen in the schematic (Low-distortion Audio-range Oscillator) the pot simply controls a DC voltage which forms the amplitude reference for the leveling loop. The sinewave does not pass through it, so there's little point replacing this part.

Samuel
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Old 21st September 2012, 07:37 PM   #429
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Originally Posted by Samuel Groner View Post
A true audiophile never stops thinking that anything must matter, eh?

As seen in the schematic (Low-distortion Audio-range Oscillator) the pot simply controls a DC voltage which forms the amplitude reference for the leveling loop. The sinewave does not pass through it, so there's little point replacing this part.

Samuel
HAHAHA, yeah, you're right.

Thanks for the information.
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Old 21st September 2012, 08:30 PM   #430
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Originally Posted by dirkwright View Post
but what ever solder he used is really difficult to work with. It won't come off very well with solder wick and I don't have a suction bulb handy.
I have found on difficult solder that I get good results if I pre-wet my wick with flux. Even if the wick already has flux in it (the flux dries out).
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