Very high current power supply (2012)

by mindcrime • 7 years ago

70 45 7 years ago

Interestingly, working with low-voltage, high-current power supply has an uncommon danger: it won't kill you by giving an electric shock, but you may suffer from serious injury due to joule heating. You would create a massive electric cooker if there's any accidental short from power to ground, especially, don't wear any jewel or ring.

AstralStorm• 7 years ago

Bonus points if high frequencies are used, as they are in this one I bet. Your things are antennas, and the transformer if any is an electromagnet too.

H8crilA4• 7 years ago

You mean 12 volts at ~unlimited amps supply ran through my body may heat me up from the inside? Isn't the human body resistance too high for that, even if you go below the skin on both ends? At 10 ohm it would be just ~15 watts, hardly dangerous given that human bodies at rest produce ~100 watts of heat.

Edit: fixed numbers.

blauditore• 7 years ago

You can also get burned without current flowing through your body, e.g. by accidentally shorting the circuit through some sweat on your skin.

segfaultbuserr2• 7 years ago

You mean 12 volts at ~unlimited amps supply ran through my body may heat me up from the inside?

No. But you'll be injured if you short it with any metallic objects while touching it, like the wiring, the board, your probe, the ring on your finger, etc.

rlonn3• 7 years ago

Try measuring your resistance with a multimeter. You'll find that it is way more than 10 Ohm, which is why 12V is not dangerous to humans.

rstuart4133• 7 years ago

Isn't the human body resistance too high for that

That must be true normally. But years ago I recall reading about someone who fixed an 12V underwater light in a pool. You would imagine that would be harmless, but he managed to create a circuit that ran across the pool. It was a salt water chlorinated pool, and after doing the job he dived in, and it killed him. I don't know how wide the pool was, but in any case the voltage across his body must have been less than 12V, and possibly a fraction of that.

sephamorr• 7 years ago

This appears to just be a 60v->12v isolated converter at ~2kW. I've never seen a push-pull topology used for this power level since it makes such inefficient use of the transformer and FETs (note it uses 4 parallel FETs for each branch of the primary). Looks fun though

snops2• 7 years ago

Having needed something like this recently, I would recommend utilising 48V-12V convertors designed for servers. Telecoms equipment has long been 48V (actually -48V) but some datacenters are moving that way too for internal distribution.

There are some automotive designs for 48-12V conversation, but these are not really available as modules as automotive is large volume and high integration. Using discrete components gets expensive fast at these power levels, a Renesas 2KW reference design I saw needed a 4 layer, 6oz PCB which would have cost ~$500 to prototype in China.

The Vicor BCM series can do 48V->12V 150A out in a very nice self contained module, with excellent EMI shielding, and takes cables directly, although definitely needs a heatsink! http://www.vicorpower.com/products?productType=cfg&productKe...

H8crilA4• 7 years ago

What did you need so many amps for? My imagination falls short of melting things (like OP did).

Bouncingsoul1• 7 years ago

Switchgear testing, for HighVoltage (~110KV++) or MediumVoltage (~10KV to 110) you usually will test only the secondary side, for LowVoltage (~400V -10KV)you can test the Breaker with a primary source, these Breakers range from 100A to 5000A.

snops2• 7 years ago

Powering some 12V motors for a robot from a 48V tether supply.

Quite easy to get into hundreds of watts with relatively small brushless motors, the type that would normally be used in hobby RC, powered from LiPos. The Vicor parts have a good amount of protection circuitry as well, useful when shorted wires can start glowing very quickly, and RC lipo packs have no protection at all.

marcosdumay• 7 years ago

Galvanoplasty, electrolysis, and many other electricity-dependent chemical reactions, strong electromagnets and small wire-length actuators (like rail guns).

baybal2• 7 years ago

Designing CPU power supplies that are efficient and are not just a great lot of buck converters in different phases (VRMs) is very hard.

On modern CPU that are all running at at around 1V, you get 1 amp = 1 watt

Switching element must survive that, and you have to be super responsive to transients, and you have to have super low ripple... I do not envy guys who make VRMs for GPUs and 200w server chips

nalllar• 7 years ago

Blade Chassis power supplies are cheap used, very efficient, and will do nearly 200A at 12V from 240V input.

Search HP 500242-001.

anfractuosity• 7 years ago

I'll second that, I believe people use them for RC chargers sometimes. I used the HP DPS 600PB for trying to drive a number of peltiers. I think mine only did less than 50A, will look into the model you mentioned.

I assume none of the blade PSUs also output 5VDC?

solarkraft• 7 years ago

I have 5 at home, exactly from a Blade Center.

Any idea what I can do with them?

dTal• 7 years ago

Some of those videos seem a mite unsafe. What's the purpose of surrounding a white-hot piece of metal with highly flammable paper? It combusted on two occasions that we see. The he just removes the paper, and you realize that all that radiant heat is now hitting the worktop and circuitry...

phoe-krk• 7 years ago

What's the purpose of surrounding a white-hot piece of metal with highly flammable paper?

He likely wanted a nice white background for his video. But, well, it backfired.

ragerino• 7 years ago

I recommend looking into so called Super Capacitors or Ultra Capacitors. They are widely used where a quick and high initial load (power)is required.

AFAIK super capacitors are used for backup power systems and electric car batteries. I think I hear that Tesla battery packs have super capacitors to protect those Litium cells from getting damaged during short high load needs.

I am currently planning a small hobby project where I want to build a small autonomous sensor station using ESP32 and LORA, powered with solar cells using super capacitors as energy buffer charged through a buck boost converter with simple MPPT functionality.

A protection circuit in front of you appliance is mandatory since super capacitors can unleash high loads for a short period of time. I use here a second buck-boost converter which outputs constantly 3.3 volts for the ESP32 board and sensors.

nickpsecurity• 7 years ago

My favorite use would be rail guns. Cuz they're awesome. :)

https://www.youtube.com/watch?v=fKEaDhDTciQ

Some are funnier than they are awesome:

https://www.youtube.com/watch?v=vAs9EHtKfVc

rubidium• 7 years ago

I've worked at a much smaller scale then those (12" length), but yes capacitors are very fun.

I used a screwdriver taped to a meter stick to complete the circuit : )

mindcrime• 7 years ago

My interest in all this started largely from a (currently stalled out) initiative to build a coil gun. Cuz they're also awesome. :-)

rathel• 7 years ago

This guy has a YT channel DiodeGoneWild. If you're into EE or dodgy stuff from eBay, do check him out. Recently he tore down a modern ATX power supply and did a very in-depth explanation.

taneq• 7 years ago

A while ago there was a discussion here (https://news.ycombinator.com/item?id=20293041) about right-angle bends in PCB traces and why we avoid them. One of the suggested reasons was that they distribute current poorly and can cause failures under high current. This video (https://youtu.be/weJdXaGRJGY) from the article is a great illustration of this in action, giving a literal heat map of current density.

TD-Linux• 7 years ago

Interesting design, though I think if isolation isn't needed, you would do much better with just a buck topology - half the fets, and no output diodes. Or a surplus supply as other comments mention.

jesperhh• 7 years ago

Damn, he is doing some crazy stuff - take a look at the x-ray experiments: http://danyk.cz/rtg_en.html

unnouinceput• 7 years ago

Having created for my personal use low voltage/high amperage transformers myself to use for house repairs when need it and already knowing the danger of using too much voltage with hundreds of amperes (where the total power would rise well above 1.5kW) I wonder about this circuitry long term usability. I know from personal experience that melting metal using such a transformer is generating a lot of heat that goes back to your transformer isolation. And my transformer would be 1.75 V in secondary or as high I ever went was 2.25 volts. So reading this diagram that has hundreds of amperes at 12V seems highly unlikely. That would be over 2kW easily and using this more then 1 minute would definitely destroy the transformer at least. I use my transformers for maximum 5 minutes then I let them cool for 30 minutes on the cold concrete.

cr0sh• 7 years ago

These are very strangely drawn circuits, particularly the power supply that powers this power supply; in that one, the circuit seems to almost be drawn right to left, at least for the low-voltage portion (which is tapped off the high voltage portion if I read things right).

This strangeness is probably - in all likelyhood - due to regional differences (east vs west schematic "standards"), plus the fact that we are dealing with power supplies, which are always messy and strange for non-trivial implementations.

Also something to keep in mind here - for the 60 volt power supply that powers this high-current supply, the AC input is 230 VAC, likely at 50 Hz (ie - European AC power standard). The circuit as-is likely won't work or will work poorly, without being redesigned for the US standard wall-power (120 VAC, 60 Hz) - or even if you use the higher US standard (220-240 VAC, 60 Hz).

Just something to keep in mind - that basically the initial input stage to the first power supply will need to be altered (and perhaps that weird low-voltage supply tap, too); everything after that will probably be OK, since it is DC after that point (albeit 300+ volt DC - so be careful!).

Very high current power supply (2012)

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