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Old 2nd August 2009, 06:24 AM   #3001
ccschua is offline ccschua  Malaysia
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Hi Max,

what is the voltage you get at BCK, WS and DATA with the DJA?
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Old 2nd August 2009, 01:18 PM   #3002
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DJA only affects BCK and I get 1,22VDC.
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Old 4th August 2009, 03:45 PM   #3003
ccschua is offline ccschua  Malaysia
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can you let me know the BCK voltage before DJA, is it ~2.6V.
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Old 4th August 2009, 10:34 PM   #3004
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The meter reads 1,24VDC.
I have not measured with scope yet.

Did you try with the trimmer R?
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Old 5th August 2009, 04:34 PM   #3005
ccschua is offline ccschua  Malaysia
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Hi Max, I just wonder what is the BCK voltage before u install the DJA. It should be a lot higher than 1.2Vdc.
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Old 6th August 2009, 03:40 AM   #3006
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Ah! I see. I guess it should be the standard Vout for the PCM2707...
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Old 6th August 2009, 09:56 AM   #3007
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Question Standing current.

Hi Omainik

Are you running in balanced or unbalanced mode?

What are you doing with the 8ma standing current of 4 tda1541A's ? (Sowter rated only for 0.6 standing current). If they are fed through the transformer primary, they would give quite some bias voltage because of the primary's DCR.

Regards

Martin
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Old 6th August 2009, 03:08 PM   #3008
omainik is offline omainik  Austria
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Hi Martin,

the current flows through the primary. I can't detect audible side effects.

recently I compared 4 parallel DAC with one single DAC. With no DEM clock injection there is a difference. With injected DEM clock there is no audible difference for me between 4 and 1 dac.

best regards

peter
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Old 31st August 2009, 12:40 PM   #3009
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Please forgive me for asking a basic question, but I'd like to use the charge transfer circuit to provide the raw DC to a simple dual voltage regulator. It's based on a LM317/337, and is set up to provide +12Vdc and -12Vdc.

At the moment it is fed by a transformer, with the centre tap on a common line to the 0v of the DC output, and the AC feeding the rectifiers, which then supply the regulators.

If I use the Charge Transfer Circuit in post 2579, would I connect the + output of the charge transfer to the input of the LM317, and the - output to the input of the LM337. The transformer center tap would not be connected, but the 0v output would still be at 0v, as it is in relation to the +/- 12Vdc output?

I hope this makes sense as I'm pretty new to electronics (started learning and reading 4 months ago!) and have found a world of joy here!
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Old 1st September 2009, 12:42 PM   #3010
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Hi Isiitoolate,
Since there are no answers yet I will try to respond. Be aware that I am no EE...
You are referring to the so called floating CT supply, which at first glance is more difficult to use in your application than the non floating, original version.

As the diagram shows, the TX center tap must be connected to the midpoint between C1 and C2. If you use positive output of the CTS to the input of 317 you can use this midpoint as ground. The same for the negative output, but this will negate the effect of the floating approach, I imagine...
Please be aware that the floating CTS has almost the complete voltage that the TX is able to give between the pos and neg output, and that C3 will see this V, so you have to check out if it is rated for that V (you have not mentioned what VAC are your TX secondaries, BTW).
If you use the negative out as ground for positive out the power dissipation in you 317reg could be high.

The second way I see that this supply could work, but I have not tested it, is making a double connection for pos out and for neg out> one pos out is the real pos out and the other is ground for the neg rail...I don-t know if I made myself clear...this should keep it floating...but the regs will see the whole V and will waste more heat...I wish EC was around to contrast this hypothesis.

Edit> you could also replace C3 by two caps in series and take the midpoint of this cap arrangement as you 0V! ...maybe you must add R in parallel to each of these C to have exactly the electric midpoint? This arrangement will divide by two the rated capacitance though...opinions please.

I hope this hepls,
Regards and congratulations to decide to try these PS> you won-t regret it.
I use them everywhere!
M

Last edited by maxlorenz; 1st September 2009 at 12:52 PM. Reason: another idea!
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