Hi,
I am trying to design my own stereo amp (2*20Watt) for the first time based on the lm3886 basiccircuits.com BOM & a Modushop Mini Dissipante enclosure (230mm*120mm*250 or 300mm depth). I started with some conceptual layout drawings & I still do not know if I need/want 1 or 2 toroidal transformers. I am planning on designing my own pcb's as I try to enjoy the project as an experience and not only the endresult.
But now for my question. I saw some articles online about multi elco psu's like the one shown below. I can even find similar psu's for 14 euro on aliexpress. These multi elco-psu's raise questions about which type of psu's are most optimal. Can someone on diyaudio help me on my way, I just need a small knowledge-kickstart from someone, I feel a little bit stuck at the moment, if you know what I mean.
I am trying to design my own stereo amp (2*20Watt) for the first time based on the lm3886 basiccircuits.com BOM & a Modushop Mini Dissipante enclosure (230mm*120mm*250 or 300mm depth). I started with some conceptual layout drawings & I still do not know if I need/want 1 or 2 toroidal transformers. I am planning on designing my own pcb's as I try to enjoy the project as an experience and not only the endresult.
But now for my question. I saw some articles online about multi elco psu's like the one shown below. I can even find similar psu's for 14 euro on aliexpress. These multi elco-psu's raise questions about which type of psu's are most optimal. Can someone on diyaudio help me on my way, I just need a small knowledge-kickstart from someone, I feel a little bit stuck at the moment, if you know what I mean.
In my opinion, you need only one transformer with 2 symmetrical output windings and a dual fullbridge rectifier. But there is a problem with these kind of multi elco psu boards. Every single elco got a different impedance to the output, especially if there are "rails", which connect the capacitors. There is a problem called galvanic coupling and its one of the major cause of EMC problems. With a multilayer circiut board it is possible, to give every single elco a single kelvin connection, but with different lenghts. So the elcos near the output clamps will do all the work and the elcos on the other side will never see a transient current consumption. The elcos next to the output will age faster, than the others. It is better to use one or two large elcos and one or two small mkp caps to reduce the highfrequency impedance.
I design psu's for a few years and analized the behavior under different conditions and small/big load transients and the liftetime under different conditions. Once i designed a DC-bus capacitor for high current high temperature inverter application. I had to use small caps, cause there were no other with high temperature capability. It took ah looooot of time to design a multilayer curcuitboard, which conducts every single cap with the same impedance
I design psu's for a few years and analized the behavior under different conditions and small/big load transients and the liftetime under different conditions. Once i designed a DC-bus capacitor for high current high temperature inverter application. I had to use small caps, cause there were no other with high temperature capability. It took ah looooot of time to design a multilayer curcuitboard, which conducts every single cap with the same impedance
Thank you for your reply. So a large capacitor-array looks high end, but if I interprete your post correctly, in reality it is not (most of the time). I will go for a more mainstream powersupply-design then, thank you for your advice.
I tried getting a nice looking symmetrical layout inside the case (maybe i install a hardend glass top) and a symmetrical design on the frontpanel. Reaching this symmetrical designlayout feels unpractical with 1 larger tranformer (D=115mm*58mm) instead of 2 smaller transformers (D=89 *39mm or D=94mm*46mm, depending on the VA-calculations). I'll keep fiddling in my layout untill I find a sweetspot, Rome was not built in 1 day!
I tried getting a nice looking symmetrical layout inside the case (maybe i install a hardend glass top) and a symmetrical design on the frontpanel. Reaching this symmetrical designlayout feels unpractical with 1 larger tranformer (D=115mm*58mm) instead of 2 smaller transformers (D=89 *39mm or D=94mm*46mm, depending on the VA-calculations). I'll keep fiddling in my layout untill I find a sweetspot, Rome was not built in 1 day!
Say I want to erect a 2-leg A-frame power tower. In a swamp. So I need concrete columns into the mud to support the weight.
Do I want 132 columns? or 2 columns?
A hundred+ little columns is a LOT of work with little obvious advantage.
While many small columns spreads the load around, it is likely that two or four large columns will carry the same load. Perhaps better because of working as "one unit" instead of many small units, each one carrying its load a little differently. And there is the problem of linking many columns to work together-- beams tying the tops together will always deflect/sag, just as wires/traces linking many caps will have voltage-drops.
Practical matters come into it. Maybe a 7-foot diameter column will do the job, but 5-foot column forms are easier to get, so I use two per footing. We often see "two big capacitors" implemented as four caps because two caps would be too long or fat to fit in the box we want. In DIY, sometimes huge-uFd caps are more expensive than a couple of half-uFd caps. At some quantity point (often a 10-pack) the price/cap falls, so a handful of caps makes some sense.
That 132-cap board is pretty, but I'd be happier with fewer caps.
Do I want 132 columns? or 2 columns?
A hundred+ little columns is a LOT of work with little obvious advantage.
While many small columns spreads the load around, it is likely that two or four large columns will carry the same load. Perhaps better because of working as "one unit" instead of many small units, each one carrying its load a little differently. And there is the problem of linking many columns to work together-- beams tying the tops together will always deflect/sag, just as wires/traces linking many caps will have voltage-drops.
Practical matters come into it. Maybe a 7-foot diameter column will do the job, but 5-foot column forms are easier to get, so I use two per footing. We often see "two big capacitors" implemented as four caps because two caps would be too long or fat to fit in the box we want. In DIY, sometimes huge-uFd caps are more expensive than a couple of half-uFd caps. At some quantity point (often a 10-pack) the price/cap falls, so a handful of caps makes some sense.
That 132-cap board is pretty, but I'd be happier with fewer caps.
It seems so indeed, still, the pictures of capicitor array's on pinterest look nice tho. 🙂 All those expensive levison amplifiers have capicitance array's too.
I read this website about powersupplies for chipamps and apparantly the carlosfm snubberized integrated powersupply is a favorite amongst alot of diy-ers. For now, I am going to search some more and try to find other nice powersupply designs and knowledge. I will probably end up with a powersupply design most diy-ers have used for a 2x20 Watt amplifier.
I read this website about powersupplies for chipamps and apparantly the carlosfm snubberized integrated powersupply is a favorite amongst alot of diy-ers. For now, I am going to search some more and try to find other nice powersupply designs and knowledge. I will probably end up with a powersupply design most diy-ers have used for a 2x20 Watt amplifier.
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