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Old 22nd November 2012, 01:17 PM   #1911
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I'm making a new reg, target is 3.3Vout 300mA, I'm using 9VAC 12VA tx, have the tx enough power for my target?
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Old 22nd November 2012, 01:19 PM   #1912
Salas is offline Salas  Greece
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Yes. It may get a little warm if good in spec. If it will get really hot then the spec would be a bit fake.
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Old 22nd November 2012, 01:26 PM   #1913
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I measured 10.8VAC at the input reg, I use dummy load 18R to simulate a power consumption of 185mA max Vout 2.894VDC, I set the current with 8R9 resistor, voltage across 8R9 is 1.508VDC = 169mA so I have to increase the current with a lower value of resistance.
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Old 22nd November 2012, 04:33 PM   #1914
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Lowered RXX1 to 4R7 I have 276mA wiht Vout 3.3V, perfect.
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Old 23rd November 2012, 09:43 AM   #1915
Magsy is offline Magsy  United Kingdom
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Quote:
Originally Posted by Salas View Post
I would rather use 1.32 to 1.35 multiplier for full bridge and 50VA transformer for AC to DC expectations. You don't want it to go over 55V when your mains value is topping. And you don't want it to go less than 50V when it is low. Do you have a rough picture for mains variations at your residency?
I've logged my mains voltage over 24 hours, 150,000 samples and it is pretty stable. The peak time dip is not caused by my premises, we had hardly anything running so I guess that happens every night as people come home from work.

Click the image to open in full size.

I guess I'll try the 40v 65va transformer and if it is too high stick some resistors on the secondary.

Thanks
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Old 23rd November 2012, 09:49 AM   #1916
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Magsy, just remember that your mains voltage will also fluctuate from season to season and from weekday to weekend depending on demographic and mix of commercial and residential customers that are also connected to the same LV circuit and same distribution feeder as you.

One day may not necessarily be representative of the mains voltage fluctuations that you experience.
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Old 23rd November 2012, 10:16 AM   #1917
Magsy is offline Magsy  United Kingdom
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I understand, the situation is not ideal re the transformer and I'll do a few spot checks but realistically living sub-urban in the UK I'm away from any industry plus I've not had a power outage in ten years; it's all a bit boring over here

I'm looking at custom transformers (2x38v), I just don't want to pay for them

Can someone confirm where the +5v headroom needs to be present? Measured after rectification and the smoothing cap? or at Q102?
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Old 23rd November 2012, 10:25 AM   #1918
Salas is offline Salas  Greece
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The sore point is the Q102 (or 202, 302) JFET that sinks current for the 3 or 4 CCS LEDS. Don't exceed 50V across it. So measure between its outer pins for voltage level.
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Old 23rd November 2012, 10:27 AM   #1919
Salas is offline Salas  Greece
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The 5V plus headroom needs be on the main filter capacitor in comparison to the desired output voltage.
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Old 24th November 2012, 05:53 PM   #1920
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Quote:
Originally Posted by pchw View Post
Samoloko,

I haven't receive the PS board from Subbu yet, so there is no original psu per se.
I built a few 3-legs regular based psu from:

regulator booster - pink fish media
and the using 3-pin regulars concept from Just one thing about music - when it hits you feel no pain

The results were quite good but not as good as SSLV 1.1, obviously. My ears are nothing to be pride of. It wasn't a night and day after I swapped in the SSLV, but in a more in depth audition, the improved clarify throughout the audio range just made the listening experience that much enjoyable.

The yellow caps are some unknown brand that I have owned for quite some time. They were new, but the voltage rating is too low for my tube projects. Since the build guide suggests 4.7uF to 10uF film caps, they fit the bill :-)

In short, it is well worth the effort to build and try!!
thank you for reply Fred
I doubt that original PSU will be close to BIB
I feel that C out and C ref filt caps define character of sound and your film caps are not known to me - they look like auricaps which are preffered for some users here - If you like to try 2 x 10 uF / 200 V auricap not XO I can add an order to your to get price discount
PS I also wait ES 9023 pcbs and psu from subbu
regards
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