Salas SSLV1.3 UltraBiB shunt regulator

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Hello . I have a question - how low i can go with voltage ?
I want to power I2S over usb kind off like xmos usb to spdif . I need 4 -5.3 v 400ma for usb side and 4.5 -5.3 for oscillator reclock 100ma. I have a transformer 20Va with 10v ac output. Obviously I would built 2 separate ultra bib . Can I power them from the same transformer ?
They would not be connected at any point on the I2S board .
I recieved with my kit PF5103 with label below 7.5 ma . Do I need one per ultra bib ? Where does it need to be installed as on pcb there is 3 of them ?
Thank you .
Going higher Vin is good for M1 performance as long as you can handle the extra dissipation.

No you must not share the same transformer secondary between two Ubib the way they are configured as standard with independent own full rectification bridges.

Lower Idss marked PFs are preferred for J3 positions.
 
Thank you Sir. So it Turned out one of Led was cooked . Replaced it and it seems that trimmer was faulty too. I have replaced those . Run it however i missed reinserting R9 so was getting 4.7v unable to adjust. Installed R9 and now i can set voltage all ok without dummy load. When dummy load connected i get 4.7v and unable to adjust voltage . When i set trimmer then red Led are brither or dimmer. Any ideas what is buggered this time. I dont want to give up. I cannot actually . I must make this run regardless. Thank you. And iam about to start building power amp wish me luck.
 
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Check if R1's Ohmic value is still OK. Then if there's still about 0.6V between its legs. Meaning the CCS system is still properly working. Determine mA by V0.6/R1. Make sure mA are enough for the dummy load value you check with. Vout/Rdum must be less than CCS mA not to limit.
 
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You are right . At first for test i installed 1 ohm resistor on the board and i connected 10ohm load but now ia decided to test what it was built for So for low value 100ma plus 100ma i selected 3 ohm resistor for current limit . I connected 25 ohm load and set voltage nicely . Can I Set it to 4.9V ? Would it work ok in a long run ? Just to be Save that during start up it does not go too high .
Shortly i will test second board for 400ma so 600ma Total - therefore 1 ohm resistor and 12.5 ohm load i hope it would set well . And maybe today I will finally listen to I2S over usb who knows.
 
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I wanted to first thank Salas for your great design. I have built the SSLV1.3 circuit and I am very happy with the results. I am using a DC supply and a mosfet cap-multiplier before the Ubib as in the pictures. I am using NICHICON UPW 220u/50v for C2 and PANASONIC FM 100u/50v for C2.

I am going to build another one for use in the second preamp and I have a question, could I use LM329 instead of the 2 LEDs for the voltage reference? what would be better?
 

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Hello. So I have managed to get going both of ultra bib. It tirned out that I must have been excedding current with my resistors that is why I could not adjust voltage but I was adjusting led power . Atleast that is the conclusion I came to.
Anyhow it is built , it provides power , it works and it even plays music . Yet I have small problem . I can hear interference kind of like distortion that you can hear sometimes when you come close with your mobile phone to a radio however it is constant and gets louder with volume . It looks as if it is coming from source. So now I have general question . Should I connect ground from both ubib to ground usb device i2soverusb from jlsounds ? I mean via screws ?
And ground from dac board and tubed I/U board . It plays music and the quality from usb improved over old separate recklocker masively. However issue do not allow to fully enjoy. Would appreciate advice and if it is wrong to ask here I would happily start new thread.
The recievier IC is CS8414 and signal from usb board set to SPDIF.
 
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Unfortunately i dont know about tube circuit as I have not got schematic . Its Abbas audio DAC 5.0 bought without enclosure as DIY. He informed that i can connect ground at the signal input to I/U board from ad1865 Digitall pcb and its best to connect in one point there only. Chassis is totally disconnected from anything currently well just the large ubib radiators made of aluminium. However those radiatory are fully isolated from ubib . So no connection to chassis at all.
I2soverusb is isolated from chassis too. No reference ground therfore as such. Not sure jow to proceed .https://youtube.com/shorts/Q7bvEwS4ATw?si=ppI59n5UF0Wmg182
Link to the video of the problem . You can hear mainly in left channel , right channel seems less affected for some reason.
 
Maybe someone can tell me my mistake with my high school maths; was trying to calculate the needed transformers myself rather following the guide.
You know, learning along the way. As I thought the recommended transformers were a bit on the higher side than I'm used to.

Taking the formula VDC=(VAC*1,414)-1,4V -> VAC=(VDC+1,4V)/1,414

5VDC -> 4,53 VAC
12VDC -> 9,48 VAC

Or is it I need to add the 5V as it mentioned to reach 5V (or) more? And then flooring those to get nice 9 VAC and 15 VAC values?
Trying to come up with the optimum transformers for my streamer and in initially thought along the lines of ~6 VAC and 12 VAC.
 
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You would want a rectified DC voltage level no less than 5V higher vs a Ubib's output rail setting in an application. Practically expect AC transformer secondary value (measured when loaded by the reg) times 1.25 for rectified DC voltage (measurable across C1) in this specific class of full bridge rectifier CCS biased regs.

Thus for a 5V DC rail streamer a 9V AC nominal secondary transformer should be a safe bet.