Construction details of A Complete 13.8 Volt, 50 Amp Power Supply

tq60

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Cleaning is easy.

Better quality to start avoids some.

Most have feedback systems to regulate voltage at load.

Downside to most is poor current limiting, meaning they provide full output but only have fuse for overcurrent.

If they can roll back on heavy loads then they can be used for battery support.

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petcnc

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Cleaning is easy.
Better quality to start avoids some.
Most have feedback systems to regulate voltage at load.
Downside to most is poor current limiting, meaning they provide full output but only have fuse for overcurrent.
If they can roll back on heavy loads then they can be used for battery support.

Well filter capasitors could clean most of the noise and a large lead acid battery connected in parallel could eliminate most of the problems but how practical that would be then?
I still look at Amazon for a 13.8V 50A PSU for $35 but I cannot find any!!!!
 

addertooth

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That is a very classic Iron Man style supply. Out of curiosity, why didn't you rectify raw AC (to give 180VDC peak voltage) and go Switch mode regulation down to 12 volts using Low RDS on power FETs in Buck Mode through a large toroid inductor. It would have much lower heat dissipation and a simpler design? I used to design classic linear power supplies, before I fell in love with the virtue of Switch Mode regulated supplies.
 
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kb58

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That is a very classic Iron Man style supply. Out of curiosity, why didn't you rectify raw AC (to give 180VDC peak voltage) and go Switch mode regulation down to 12 volts using Low RDS on power FETs in Buck Mode through a large toroid inductor. It would have much lower head dissipation and a simpler design? I used to design classic linear power supplies, before I fell in love with the virtue of Switch Mode regulated supplies.
Yeah I was going to say much the same but to each his own. As noted above, if it's being used in an EMI-sensitive environment, I can understand going linear, though filters can fix that on a switcher as well, it's done all the time.

I'm an EE, been into electronics since I was 12, and have designed and built many power supplies, both linear and switchers. If your goal is for it to be a learning experience, doing it yourself is great. On the other hand, if it's to get something up and running right away, buying one is the way to go, because building one will cost way more than getting it off the shelf (admittedly, I'm comparing a linear with a switcher, but which is better depends upon its intended use).
 
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petcnc

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That is a very classic Iron Man style supply. Out of curiosity, why didn't you rectify raw AC (to give 180VDC peak voltage) and go Switch mode regulation down to 12 volts using Low RDS on power FETs in Buck Mode through a large toroid inductor. It would have much lower heat dissipation and a simpler design? I used to design classic linear power supplies, before I fell in love with the virtue of Switch Mode regulated supplies.

I am not an electronics engineer by profession! Just a hobbiest. As I stated in the beginning it is not my own design. I just followed the initial design and build it. If you have designed a similar switching PSU I will be very happy to build it and replace the linear one!
Petros
 

petcnc

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If your goal is for it to be a learning experience, doing it yourself is great. On the other hand, if it's to get something up and running right away, buying one is the way to go, because building one will cost way more than getting it off the shelf (admittedly, I'm comparing a linear with a switcher, but which is better depends upon its intended use).

I dont know about you but I enjoy the "building" part of everything I make!! I know it is cheaper and hassle free to buy everything from shelf but where is the joy in that?
If you don't invest in a $1000 machine and $20 on raw material to make a part that costs $1, then you will not understand what I am talking about.
Besides, whatever I have bought (china made + cheap sold) lasted one season and usually left me looking for replacement in the middle of a job.
It might be my bad luck, I dont know, but I am a little cautious with cheap china euipment.
For al the above rasons I decide to build something my self and know each part and function of it if it fails instead of relying to a questionable design euipment from far east
 

addertooth

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PetCNC,
I will agree with your last point. Most Chinese electronic equipment is designed with lowest cost as a defining factor. As such, they lack the safety margins that a home builder would use (things like transistors and FETs rated at 2 to 4 times the current which be demanded of them).

Almost everything I designed back in the day had at least a 4 times factor for a safety margin, as it had to have a six nines reliability factor 99.9999 reliability. I also had to be aware of component aging, so thinks like ceramic disc capacitors were used instead of mylar, and tantalum capacitors were used instead of electrolytic capacitors. Carbon composition resistors were used instead of metalized resistors, and all of the inductors were hand-wound. Uptime was designed for Decades, instead of months or years.

Nobody designs this way anymore, unless it is for a space mission. Even modern aircraft are not designed with these considerations anymore. In the commercial world, the accountant wields more power than the chief engineer.
 

cathead

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Not to rain on the parade, but more about offering alternatives: If you're building one for fun/education/a hobby, fine, otherwise, a switcher supply with the same specs is $35 on Amazon.

Switching supplies generate a lot of radio frequency noise so not the best for some applications.
I avoid them like the plague.:faint:
 

kb58

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Switching supplies generate a lot of radio frequency noise so not the best for some applications.
I avoid them like the plague.:faint:
Agree completely, that for some applications, they're perfect.
 
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