SSLV1.1 builds & fairy tales

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B&W_arthur

Member
Joined 2006
The 3 2sk170 GR give Idss: 5.5mA, 4.2mA and 3.2mA.

The following were done:

1. replaced the 2SK30As

2. replaced the 10k and put back the 3k resistor.

3. the voltage across R301 dropped to 1.08V, so R301 (4.7Ohm) was replaced by 3.3ohm and now I get appr 327mA. much closer to what I am targeting.

After all these changes, another measurement was made:

at the start, Vout was 32V and voltage across R301 was 1.08

after 10 mins, Vout was 33.55V and voltage across R301 was 1.08V

after 15 mins, Vout was 33.7V and voltage across R301 was 1.08V

The latter seems very steady now. Not sure the former will drop or not as I went out before it was working for 30mins.

PS: it seems that replacing 2sk30a by 2sk170 caused the voltage across R301 drop 0.2V, which is the difference between the Vds of the 2 jfets. ;)
 
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B&W_arthur

Member
Joined 2006
AndrewT said:
The Salas regulators were original designed for 2sk170 jFETs.
It turned out that some did indeed have to be genuine sk170, but not necessarily bl grade.

Some can be swapped to low gm, high Vp, types and performance does not suffer.

But a few MUST be sk170. These few MUST be kept.
Click to expand...

I have seen somebody using BF245(A?) for shunt regulator, if I recall correctly.
The Vgs(off) of it is -0.25V which is close to sk117's -0.2V. Worth a trial?
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
A good quality cap in Vref filtering is always a good use for it. You just have to be careful with the trimmer not to start the test with high Vout >6.3V. Unwind the trimmer to low value before first power on to test-set Vout. Or calculate well if its a normal resistor. If its Leds their Vf is highly predictable and so on and so forth.
 
V

Vbenonisen

Member
Joined 2010
Hello!
I'm planning on placing SSLV regulators on top of each other with short standoffs in between. This necessitates the removal of the rectification diodes and the smoothing capacitors (10000uF and too tall) from the PCBs and onto a separate PSU board.
How big decoupling capacitors (in uF) do I need on the SSLV's to get everything working correctly? I might add that the voltages and currents are in the low range, and that the external PSU board is 20-30 cm. away from the SSLV PCBs.

Regards,
Vidar
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
The smallest in physical size you can use with some uF are tantalum 10-47uF. Use well higher voltage than applied. 35V. Watch the polarity bcs when tantalum fails it fails catastrophically and shorts. Another option can be 47-100uF good quality electrolytics.
 
drpro

drpro

Member
Joined 2014
Salas, I have a question regarding your shunt regulator. I am very new to the world of DIYA, though I have some background in electronics. I have ordered a board and kit set from Teabag for this next group buy.
My plan is to use your shunt regulator to power a BA-3 preamp, which will be a future build. What I don't know and my skills are not such that I can determine what current the BA-3 pre needs, hence knowing what parts are needed to complete the shunt regulator with sufficient current available.
Any help/advice would be appreciated.

Regards,
David
Nashvegas
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
I see 8mA+45mA=53mA bias per BA-3 preamp channel. So 220mA CCS per section for a common between channels dual polarity SSLV1.1 should do. I have listened to such a pre with such a reg very recently and it was really nice. British member Backbones was using such a reg for the BA-3 as input stage in the full power amp concept as well, if I remember correctly. Its somewhere way back in this thread.

image.php
 
F

freeman

Member
Joined 2010
Hi everyone,
Here is a photo of my first salas shunt reg build. This feeds the subbu dac v3 with +5V. I used the BJT option and replaced the original psu. My transformer is 12V-2A and the transistors barely get warm. Initial impression is that bass is deeper and more detailed. :up: Thanks to Salas and TeaBag.
Best regards.
 

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lampes

Member
Joined 2007
Hi all

I did finished my salas ver1.1 positive rail (24V, 195mA shunt, 35mA load) with excellent matching of theoretical values and results.

The same did not happened to the negative rail though.

I did match Idss current of the Q101, Q102 in order to have similar currents but on the negative i do have a significant lower shunt current at 123mA.
Voltages on R101 is 1,32V=> 194mA but on R201 is only 0,84V => 123mA. Both resistors are 6.8Ohm.

Do you guys have any idea on what to check to correct the negative rail?

Thanks

Thanos
 
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