The simplistic Salas low voltage shunt regulator

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There is the 1.1 bib soon on new gb round that you can use in Mosfet for the 5V and I would recommend the low vgs ST output Mosfet p2p version of the Reflektor for lower Volts as discussed some pages before and made in Japan.

with 2 days before you wrote this post the the guy here Salas Reflektor +3.3V with MTP3055VL: Kon??????? wrote the following ''Replacing STP55NF06L with MTP3055VL, I got great improvement. This result suggests that it is better for the Shunt MOS-FET to be less Cxxx''

should this be taken into consideration?
 
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His goal is having lowest forward on voltage and lowest Crss possible for stretching a Mosfet output Reflektor down to 3.3V use. There are 2 things at odds when there. 1. The available voltage left across the mirror. 2. The bumping capacitance curve of Mosfets at low voltage. Those are the reasons I originally suggested him to get testing with the best logic level Mosfet he can in those respects. Nonetheless, from the moment you have it working above 5V and more so 10V up, the STP or the MTP straighten out for Crss much. The STP is a much higher transconductance device in high current but I did not see the Id/Gfs curve in some datasheet when I looked for the MTP to compare at 1A or below. They could be near at low current. In a nutshell he does well to pursuit the lowest capacitance and on thresholds (VgsTh,Vsd) in his application but for higher Vo it may be increasingly irrelevant. The two types are similar in price and available and you can compare in your own app.
 
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If something "rings" it will do it between 2-6MHz usually from a couple of times I have seen it in wrongly made ones some friends brought to me to debug. If the scope has high bandwidth it can bring in environmentally born stuff also and we should know what is what. I would start with the probe at 1X where its naturally slow and the system noise is best on the screen. If clear I would go 10X and sweep across. First with the scope in 20MHz limit mode. Sure oscillation has a sinewave profile sometimes even perfect in shape or about and 20mV-200mV amplitude from what I have seen on those problematic p2p builds. Other stuff can be much lower frequency periodic "spikes" from digital equipment interacting with the rail and can be fought with extra 100uF across the sense lines and/or 0.1R resistor in series on the force line.
 
Salas: I know you posted somewhere how it was possible to modify a positive supply pcb to negative, with only some simple changes.
I've been searching, but haven't found it this time, can you re-post or redirect me to the post?

Edit: ok found it in the SSLV1.1 thread.. in THIS post. :)
 
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I am building a phono preamp board which requires +/-15V supplies, which I intend to provide from a SSLV power supply. I also want to experiment with a Salas RIAA phono preamp. Those seem to require a single-ended supply on the order of 20-30V. I would like to use one transformer, some rectifiers, and some capacitors for the initial "primary" supply. I would like to be able to move some wires around to switch from +/-15V to +25V(ish). The SSLV boards conveniently come in triplets, a +/- pair and an extra positive regulator.

So my question: Would a 2*15V transformer be a good choice for this? Lower? Higher? I am assuming the shunt will operate at no more than 300mA, probably more like 200mA
 
The latest folded cascode MC phono version requires +35V... follow the rules of thumb VAC=~VDCout and VA>=VAC*(3*ICCS).

So if I am considering at some point to build the folded MC version (I don't even have a MC cart, just thinking about the future) my transformer should have AC out on the order of 36V, so a 2x18V secondary would be OK. If I use that transformer to feed a BiB to get a +/-15V supply for the other preamp I'm working on, is that going to be a problem? I presume the regulator is going to have to dump a bit of voltage and run hot for a given current. Maybe some heavy-duty resistors will be in order to step the voltage down. One nice thing about the Salas shunt is the current consumption is predictable and consistent!
 
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Only a matter of wasting your extra energy to heat in clever RC passive filter manner as you wrote, or just dumping it on the input Mosfet sink. Not a huge deal when at the 200mA mark or about. Just roughly calculate the thermal design before you start. Being the wattage of the RC's R element or the capacity of the sink.
 
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