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How to build Linear PSU?
How to build Linear PSU?
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Old 21st November 2018, 09:02 AM   #21
FauxFrench is online now FauxFrench  France
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Originally Posted by techmate View Post
thank you very much you did an excellent job, will be so nice if i could print a pcb and then solder the stuff on it....ooo dreamin'.....

I am a Vero-board type myself because it leaves me the flexibility I need. The LM317 kits I have seen use small insufficient heatsinks. You need good heatsinks, eventually a metallic casing you can use as heatsink (be aware of the needs to insulate the chip cooling pads). You may also need some experience with Vero-board.
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Old 21st November 2018, 01:34 PM   #22
techmate is offline techmate
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Originally Posted by FauxFrench View Post
I am a Vero-board type myself because it leaves me the flexibility I need. The LM317 kits I have seen use small insufficient heatsinks. You need good heatsinks, eventually a metallic casing you can use as heatsink (be aware of the needs to insulate the chip cooling pads). You may also need some experience with Vero-board.
no experience with vero board but this is just a new challenge, i think is going to be fun anyway. Now i have to start looking for the parts and make a list of the stuff that i really need. BRB
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Old 21st November 2018, 08:30 PM   #23
FauxFrench is online now FauxFrench  France
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no experience with vero board but this is just a new challenge, i think is going to be fun anyway. Now i have to start looking for the parts and make a list of the stuff that i really need. BRB
If you decide for Vero-board, use single sided fiber glass types.
Pertinax (brown Bakelite) boards quickly loose the PCB pads when heated and double-sided fiber-glass becomes a nuisance because the solder flows through the unused via's and create solder-bubbles on the component side.
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Old 23rd November 2018, 12:37 PM   #24
techmate is offline techmate
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Originally Posted by FauxFrench View Post
If you decide for Vero-board, use single sided fiber glass types.
Pertinax (brown Bakelite) boards quickly loose the PCB pads when heated and double-sided fiber-glass becomes a nuisance because the solder flows through the unused via's and create solder-bubbles on the component side.
well at this stage i don't really have better options...or i do...?! yep i will pay attention, thank you
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Old 9th January 2020, 12:02 PM   #25
Mrdrewk is offline Mrdrewk  United States
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Any movement here? Reading through posts, seems like there's more questions than answers! I'm also interested in DIYing a linear PSU. I'll be powering an Allo Boss DAC via USB-C. Starting with an ebay kit - then I'll need to adapt it to the USB c interface. Where to next?! Thanks.
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Old 29th November 2020, 08:04 AM   #26
organics1 is offline organics1  Germany
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Mrdrewk,
In case you're still interested, check out these modules: Audio Selbstbau, Thel, Endstufen, Vorstufen, Aktivweichen, analoge Netzteile, Netzfilter.
You can also get some of the same modules in customizable (cheaper) kits: Bausaetze.
Haven't tried these yet but will do so in a few weeks to replace a couple of wall warts. I'm a Yank living in the Frankfurt area since 2014 and THEL is located a few miles away from my little village. I'll go there to pick up the units.
Audiophonics also has some interesting and economical modules: AUDIOPHONICS PSU S3-LP Linear Power supply Module DC LT1083 - Audiophonics.
Since linear PSUs seem to be the latest fad for us audio nuts I've been investigating and have come away quite shocked at what people are paying for this stuff, especially for PC supplies. Smelling the blood in the water, the Chinese have entered the market big time, with "big" being the operative word on prices. Hopefully, a reasonable diy solution isn't far off.
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Old 29th November 2020, 08:15 AM   #27
jean-paul is offline jean-paul  Netherlands
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Follow up on post #6. It is not that hard to build a linear PSU. It is hard(er) to build a safe and excellent measuring linear PSU. Always use metal casings with a filtered IEC inlet and a real power switch (officially both poles should be switched). Casing should be connected to PE, the DC parts GND can be connected with a 10 Ohm 1 W resistor to PE. Always use M3 bolt/nut and washers for the PE connection to the metal casing and always verify things make good contact. Always use fuse holders and choose the right value fuse. Easiest is a filtered IEC inlet with built in fuse holder and power switch so you have less metalwork to do.

Make sure you use low noise regulators or a discrete circuit that is low noise. Avoid old generic regulators that are noisy. The filter capacitors should be chosen so that ripple voltage is low at the highest load. Rule of thumb is 2200 F/A for 1V ripple. When possible use CLC filtering.

You will find out that modern low noise regulators are often low drop out types which is even better. Discrete circuits can be better but IC regulators circuits are simple and can be just as good or even better. If you carefully choose transformer voltage you can adapt things to each other and have least heat generation and good quality regulation. Best transformers are R-Core types followed by EI types and last toroids. The latter are cheapest and certainly not the best. Choose the transformer to be 2x the required load ratings.

The combination of things can be a true improvement on generic SMPS that are delivered with equipment but the devil is in the details as always. With todays RF signals in the air shielding and filtering have become necessities. And please note that using an LPS with device A does not mean the SMPS of device B is not polluting mains in your home....
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Last edited by jean-paul; 29th November 2020 at 08:33 AM.
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Old 29th November 2020, 10:35 AM   #28
organics1 is offline organics1  Germany
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jean-paul,

Thanks for the advice on the R-Cores. Didn't know that. So, where do I find top quality R-Cores? So far, my Google search has turned up relatively inexpensive stuff on ebay. Until now I was considering the Supreme Audio Grade V2 toroids from Toroidy in Poland, which cost about $75 US for 20VA.
So, am I just paying for the silver can bling, and one of the $20 jobs on ebay is the better way to go?
Confused.
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Old 29th November 2020, 11:31 AM   #29
jean-paul is offline jean-paul  Netherlands
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Because of a combination of luck and coincidence I got hold of a lot of R-core transformers years ago otherwise I would probably never have tried them. Since then I always use them whenever I get the chance.

Many toroids leak and they are too high bandwidth so they don't filter HF/RF as much as I like them too. The fact that many of them can be used for output transformer says something. Most are also very susceptible to DC component on mains voltage which causes annoying mechanical hum. All anecdotical in the eyes of toroid lovers but I experienced it too much to have them at the top of my list. EI types in general are better but then also the challenge to find the good and silent ones. I wish I would not say this but older EU made stuff can be very good.

True is that toroids are easy to produce, easy to mount and that you can find them in any catalog/website. The explains why they have become standard just before SMPS (which will be/is standard also for other than quality reasons). As there is not much choice I also use toroids now and then and the Sedlbauer are good.

I am in audio for a very long time and know how to build a good linear PSU but wanted to get to know the most recent regulators so when I was in quarantine I made around 12 linear PSU's based on various regulators and all perform better than the SMPS they are ought to replace. This with regards to noise, RF/mains pollution, HF/RF susceptivity and subjectively (so soundwise). Point is that they are more expensive and it requires careful design to have them performing excellent. My own forgotten SBT PSU as published here still holds up quite OK in the 3A range.
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Last edited by jean-paul; 29th November 2020 at 11:46 AM.
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Old 29th November 2020, 12:56 PM   #30
FauxFrench is online now FauxFrench  France
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I will add to the clever words of Jean-Paul that an issue to address up-front is what are the most important qualities you want the linear power supply to have. You do not get all qualities in the same design.
If you design for use with a high quality DAC or microphone amplifier that may be supply-rail-noise sensitive, you can use a shunt-regulator design. You do not use a shunt-regulator design if the load has a high and varying consumption. The advantage of the shunt regulator is that it can be designed with low noise and good step response. You may consider the new generation of low-noise regulators though they are expensive and less noise than what is needed is just more expenses than required without a further advantage.

For a load needing a rather constant voltage but having a heavily varying consumption, like a class AB power amplifier, a more simple design with good dynamic properties (load response) is suited. Particular low-noise designs are useless among other because the dynamic consumption will cause much higher voltage swings than the regulator noise. A design with an emitter output I find is suited because of the intrinsically low output impedance of an emitter, where the regulation loop only needs to do little correction when the load current changes importantly.

With an input voltage not much higher (or lower for negative) than the output voltage, a low-drop design, typically with a collector output, may be a necessity. Such a situation is 3.3V out from a 5V input. Reduced heating than for the other configurations but typically with less good load-response compared to an emitter output and more noise than for the shunt-regulator. You don't get all in one.

SMPS designs equally have some very good properties, like very good efficiency and power handling levels, but also some drawbacks like noise and sometimes step-response.

So, for a start it is very important to identify your supply needs and following you choose a regulator concept that is suited. Let's eventually discuss your needs for a particular application here in this thread. I have noticed a tendency among certain members to ask for the “one-fits-all” best regulator design, typically assuming that low-noise is most important. In most cases, low-noise or “standard” doesn't make a difference except for the price. Regulator design is, as written by Jean-Paul, not terribly difficult if you understand a few basic principles. One important basic principle is that you need to know your regulator requirements before choosing the regulator concept. Just like when you buy a car that either needs to be practical, or comfortable, or economical, or easy to park in the city or sporty and no model fits all uses.

Describe your use and we can advice you a suitable regulator concept.
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