The simplistic Salas low voltage shunt regulator

[Salas]

K-wood is talking about very high. Remember you need 10X the offending frequency in bandwidth. If you get something in say 200MHz then you need a 2GHz instrument! So magic finger could be a rough indication indeed. My line of thought is, when there is oscillation there is hum pick up too in my experience with regs. I normally see characteristic comb like harmonic noise in the low band on FFT, and thicker oscope line if there is a gremlin I can not directly catch. So if the finger test gives less hum trouble with a lower hfe transistor in your case, either there is actually some very high MHz trouble with high hfe, or you just get it to jump easier with high hfe when loading the node in the errr... traditional way. Interesting scenario, because we had been left questioning about that. Screening etc. Wide bandwidth is cool but has nitpicking to do many times.

 

[iko]

Yes, good point about the line being thicker when there is oscillation above what the scope can show. The line was very thin in my case. Oh, one point that should be important. That effect only happened when the load was active, many milliamps sine wave load. So when I touched the bjt with the finger the result was better load rejection, as though the output impedance became lower. Not by much, only a few tens uV.

With a passive load the trace is flat.

Another thing to keep in mind is that the prototype was out in the open, not in a case.

I was hoping to finish another prototype with the finished pcb tonight if I have time, so I could run some more tests. The board is etched for two days already and I'm burning to try it out

 

[Salas]

Many parameters indeed.

Errr...difficult to ''point the finger'' then!

 

[stormsonic]

So, I can also use the 2SK369-V (I have a full box with this thingies lying under my bed ) in this design as drop in replacement ?

Yes, but use them with small resistor between gate and source to limit current. It is waste of good part for this purpose

2SK170 can be found here:
2SK170 :: Other Transistors :: Transistors :: Semiconductors :: Electronic Parts :: Banzai Music
I think this price is for GR grade, BL grade is little more expensive

2SK ...
BL grade

Searched phrase: 2sk170 // Elements and components electronic parts - TME - Electronic Components
I think this is GR grade

 

[merlin el mago]

+-shunt regulators for Piccolo MC Headamp by Jim Hagerman

Hi Salas,

I need your help please, I want to do your simplistics low voltage shunt regulator to feed the Piccolo MC Headamp made by Jim Hagerman. I suppose that the MC needs: positive rail +7V & negative rail -3V with a power consuption of 15mA. I read all the thread & can not see any schematics to feed the Piccolo

Piccolo schematic:

Thanks in advance for your kind advice.

Best,

Merlin El Mago

 

[Salas]

No 3V from this Mosfet reg, since the Vgs only is about 4V.

 

[merlin el mago]

For positive rail +7V?

 

[merlin el mago]

Is possible to get 3.3V changing the mosfet for Jfets:

-Positive rail Njfet 2SK2013 instead IRFP9240
-Negative rail Pjfet 2SJ313 instead IRFP240

merlin el mago

 

[AndrewT]

how about an opamp buffered voltage reference for <5V supplies?

 

[Salas]

Soon Disco is going to thoroughly test for qualities the one with BJT shunt element able to go down even at 1.5V for No26 tube heater. http://www.diyaudio.com/forums/tubes-valves/151421-26-pre-amp-22.html#post1996668

Also J.Gerhard is working on it and will evaluate fully a possibly upcoming V1.2 in tandem with his Mpp phono.

 

[merlin el mago]

AndrewT, I have some from Erno Borbely: output noise over the audio frecuency ranges is less than 5uV.

Salas, thks for info, I will be attentive both designs: Disco BJT shunt element No26 tube heater & J.Gerhard V1.2

 

[Woodenhead]

Hi, just a quick question, is the latest version of the SSS (v1.1) here?

 

[Salas]

See posts 1310,1384,1462

 

[beetle]

Hmm... I´m thinking about using that Shunt for a XOno. Like to hear what happens... Nowdays I have one with LM317AT regulators. I´m pretty much sure that it is not too hard to beat them.
For the XOno I have to have 30V. I was simmulating Salas Shunt with 11 instead of 5 LEDs and increased R5 to something about 40Ohm. As ltspice doesn´t have a BC550 on board, I decided to use an some MJE something which I can not remember now. Had that model somewhere.

What so ever. Simulation shows 30V. Are my modifications to gain 30V ok?


cheers,
Rene

 

[iko]

ltspice has a bc547c model, you can use that.

 

[disco]

1.5V shunt regulator

Hi, here's the schematic I use for heating direct heated triode filaments. It works very stable at 1A and more, output ripple is in mV range. You can use my layout or make your own, raster is 2.54mm. Make sure you use thick conductors if currents are exceeding 250mA.
Thanks Nick, it's a good job you did on this one!

 

[Salas]

Good implementation and testing on this one Disco. 0.66V/R1=ICCS for anybody aspiring to use for other currents. In theory it can do well at 1.2V even.

 

[iko]

It's nice and simple. One question, how does it compare to some other filament psu if you tried others?

 

[HiFiNutNut]

Salas and others,

I have just come back from my overseas holiday and am ready to be back to DIY again.

What diodes subjectively sound best for rectification?

I am currently using 1N5822 low drop power schottky rectifier 3A.

The higher current rating is necessary for peace of mind - I sometimes use over 100,000uF low ESR for smoothing so the turn-on "short-circuit" current may be huge. I guess the regulators I will build will draw up to 1A constant current.

I can use diodes about or under 40V.

Regards,
Bill

 

[quanghao]

Hi, here's the schematic I use for heating direct heated triode filaments. It works very stable at 1A and more, output ripple is in mV range. You can use my layout or make your own, raster is 2.54mm. Make sure you use thick conductors if currents are exceeding 250mA.
Thanks Nick, it's a good job you did on this one!

Very nice!!!