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Old 2nd August 2007, 12:15 AM   #791
DcibeL is offline DcibeL  Canada
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I thought I already did. The impedance of the zener will be lower than the value of the resistor that would be in it's place otherwise. Two zeners in parallel further reduces this impedance.
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Old 2nd August 2007, 01:16 PM   #792
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Quote:
Originally posted by DcibeL
I thought I already did. The impedance of the zener will be lower than the value of the resistor that would be in it's place otherwise. Two zeners in parallel further reduces this impedance.
The impedance of the regulator circuit is entirely dominated by C1/C2. The junction capacitance of a 1W zener is pretty small (a few pf).

You might get a hair lower noise since the zener noise of the two diodes are uncorrelated.

Now you might want to sweep that circuit over temperature and tell us how the two parallel zeners perform.
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Old 25th November 2007, 03:01 PM   #793
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Hi Russ and Brian,
I'm reading Audio Solutions guide from TI and I saw they released a new volume control, the PGA2320 claiming improved performance over 2310. It uses +/- 15VDC supplies.
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Old 25th November 2007, 07:19 PM   #794
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See our site. We already have (actually for quite a while) a PGA2320 product in the works: Pogo.
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Old 26th November 2007, 12:53 AM   #795
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Oops!
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Old 26th December 2007, 09:27 PM   #796
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Hi again,
I made a USB NOS DAC plus headamp for my Dad who is a dentist about to retire: he began to love navigating through Youtube and listening some opera singer from the past...just as his son!

USB receiver comes from Doede, NOS DAC is self made "á la Doede" and headamp is the famous Kookaburra with OPA2227 opamps.

Click the image to open in full size.

I used a front plate which belonged to his ancient dental machine, Japanese, very well made...
The box was difficult to make even with wood parts...two stores.

The sound is warm and inviting, not the best in detail but one that lets get listened to very easily, and the bass is terribly good.

Cheers,
M
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Old 30th December 2007, 08:52 AM   #797
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Thanks to Russ and Brian for the guidance and the PIC

Today I got the preamp and headphone sections working. I have two question

1. Has anyone measured the dc output at max volume?

2. Brian any chance I can buy a few of those -95 to 0 and 95- to +24 PICs
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Old 30th December 2007, 11:20 AM   #798
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Drop me an email.
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Old 6th March 2008, 06:53 PM   #799
alexcd is offline alexcd  United States
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I was inspired by the Kookaburra design to use the same PIC and code to control two PGA2310's. The difference is that I have the digital logic going straight to two PGA2310's. I didn't use pull-up resistors (47k) or series resistors (10k) as shown on TI PGA2310-EVM (eval board.) I don't know if these are required but I am not getting the VC's to control signal level at all with a perfectly good 0-5V input to PIC. I also used a potentiometer and ADC inside PIC as Russ & Brian have done. Are those resistors most likely the missing link?
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Old 10th March 2008, 01:54 PM   #800
alexcd is offline alexcd  United States
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Anyone?
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