Help me decide which ebay dac please?

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little eddy
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Post by little eddy » Wed Nov 14, 2012 1:31 pm

Mike H wrote:I would say no, the input side of a LM317 must be kept positive relative to the output side. In situations where the input may become less positive, a reverse protection diode should be added across the chip so the reverse Voltage does not exceed about 0.6V:
So I could fit a protection diode across the regulator. What about a solid link?
Thorens TD-125 & 'Snail' phono/pre, NAS/SBT, CS4398 DAC, Rocky KT66 amp, still messing with OBs.

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Mike H
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Post by Mike H » Wed Nov 14, 2012 2:49 pm

Sorry just read this again:
little eddy wrote:If I have no components/supply to the supply side of the three LM117 regulators,
Are these surface mount? (SMD)

I thought you meant a fully populated board, but apparently not, comes with just the LM317 SMD's fitted on?

If nothing else is connected to them then your first idea should work after all.
 
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little eddy
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Post by little eddy » Wed Nov 14, 2012 4:35 pm

Yes they are smd hence my reluctance to try and unsolder, I thought they were small LM117s for 3.3 and 5V. The 3 of them can be seen just below the centre on this link: http://www.ebay.co.uk/itm/PCB-SMD-CM102 ... 1053wt_932

I intended to connect the new off-board regulated supplies via the adjacent smoothing capacitor connections since these will now not be fitted. These are of course connected to the output and 0V terminals of the regulaors but the supply terminal will not be connected to anything and allowed to assume its own potential.

All of the up-stream power supply components below the regulators in the attached will not be fitted.
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Mike H
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Post by Mike H » Thu Nov 15, 2012 10:01 pm

Right I get it now, OK then, what you said originally. :D
 
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little eddy
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Post by little eddy » Sun Mar 17, 2013 1:07 pm

So now got most of the bits for the DAC. I have looked at a potential layout and have a question about the layout as per the attachment.

The tx radiates a field if an I recall correctly this falls off as a square of the distance and the field strength I guess is also a function of current.

As you can see I have this next to the DAC pcb so what should be the minimum gap I should be aiming for given DAC low currents? I also guess mounting this vertically to maximise the gap would be beneficial so with circa 2" gap I should be OK.

Secondly I have bought one of the Chinese R-core transformers with three 9V outputs. From the attached photo, do I assume right that for a 230V input, I connect yellow to blue and the mains across brown and red?
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IMG_0301.jpg
Last edited by little eddy on Sun Apr 14, 2013 11:41 am, edited 1 time in total.
Thorens TD-125 & 'Snail' phono/pre, NAS/SBT, CS4398 DAC, Rocky KT66 amp, still messing with OBs.

little eddy
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Post by little eddy » Sun Apr 14, 2013 10:33 am

Absolutely astonished that it works first time. Initial impressions are that it is an improvement over my initial build.

Will leave it playing for a while and tidy it up over the next week or so.
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Post by IslandPink » Sun Apr 14, 2013 11:41 am

Good effort ! :D
You must have put in some careful work to get it going 1st-time .
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Andrew
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Post by Andrew » Sun Apr 14, 2013 12:25 pm

Excellent, nice use of the Gardeners, are they the 600R or the 10k ones? Did the power supply modules work out OK?
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little eddy
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Post by little eddy » Sun Apr 14, 2013 10:14 pm

Andrew wrote:Excellent, nice use of the Gardeners, are they the 600R or the 10k ones? Did the power supply modules work out OK?
600R ones from SteveS.

Modules are working fine but I'm sinking around 50mA on each one via the centre-tap resistors.
Thorens TD-125 & 'Snail' phono/pre, NAS/SBT, CS4398 DAC, Rocky KT66 amp, still messing with OBs.

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Post by Andrew » Fri Apr 19, 2013 4:44 pm

little eddy wrote:
Modules are working fine but I'm sinking around 50mA on each one via the centre-tap resistors.
Can't imagine they'd even be warm at that, have you tried a lower amount?

I would check-in with Simon he said he was going to try a different chip on the cap multiplier which may work better for this task. I haven't heard from him so I don't know how he's getting on with his experiments.

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simon
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Post by simon » Fri Apr 19, 2013 6:28 pm

Sorry, not had chance to try it yet.

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