Power supply amperages for full pit?

[jrsteensen]

Starting to work on my electrical layer a little more in depth. Going to need 3.3v, 5v, and 12v throughout the pit. Curious if anyone has a ballpark figure of Amperages required for the full pit. (Obviously, ballpark - haven't listed out every load yet.)

 

I'm kinda hoping 15A supplies will be enough, but have the feeling that may be fairly anemic.

 

Going to be using a mix of arduino minis, megas, and Raspberry Pis throughout the pit.

[agrasyuk]

lower end generic PC PSU will give you all these voltahes at 200-250W easily, I cannot imagine you going to reach anywhere close to that capacity

[jrsteensen]

lower end generic PC PSU will give you all these voltahes at 200-250W easily, I cannot imagine you going to reach anywhere close to that capacity

 

While I agree, I don't really feel comfortable hooking this up to a hacked PC PSU.

[BravoYankee4]

Well, not sure what kind of pit you will have but a single led typically needs 20mA. Then you can have 750 of them in parallel on 15A.

If you have several in series you could have a multiplier of 3-5. So, a couple of thousands of LED's won't be any problem :)

 

If you are going for real light bulbs it will be less of them, since they require more power. Not sure what the power usage is for a magneto switch, but it can't be that much.

Servos doesn't require much either.

[BravoYankee4]

While I agree, I don't really feel comfortable hooking this up to a hacked PC PSU.

 

Do you really need the 3.3V? If not, a standard 4pin molex connector (that one that is used for harddrives etc) is the only thing you need (i.e no need to hack the PSU).

[ClayM]

I am also looking for PSU for the pit. I want to use 12v rail for panel backlights. The hacked PC PSU I am thinking of using is 300w. According to the specs DC output on 12v rail is 15 amps!. 5v rail is rated 30 amps.

 

My question here is do we have to worry about short circuit protection? These kinds of currents could create a pretty ugly meltdown could they not? I realize there is short circuit protect in the PSU but is that safe enough?

 

I was thinking of using 2 amp fuses after the PSU to supply several isolated busses.

 

Clay

[BravoYankee4]

I am also looking for PSU for the pit. I want to use 12v rail for panel backlights. The hacked PC PSU I am thinking of using is 300w. According to the specs DC output on 12v rail is 15 amps!. 5v rail is rated 30 amps.

 

My question here is do we have to worry about short circuit protection? These kinds of currents could create a pretty ugly meltdown could they not? I realize there is short circuit protect in the PSU but is that safe enough?

 

I was thinking of using 2 amp fuses after the PSU to supply several isolated busses.

 

Clay

 

Having a fuse in the circuit is never a bad idea.

[Hansolo]

Having a fuse in the circuit is never a bad idea.

 

Agree. I plan to use several smaller circuit breakers as they are not that pricy. Also rememeber to use addequate wiring. Think my setup will have 6mm2 from the power supply to the circuit breakers, and then after that I will dimension the wires after the individual circuit breakers.

 

Cheers

Hans

[jrsteensen]

I've been studying it, and I think I will end up going to a quality PC PSU. Actually found a really good tutorial on modifying them so you can use all the amperage on a rail. I'll break the 3.3, 5 and 12V rails out to individual toggles and circuit breakers, then to ganged terminal blocks throughout the pit. (My goal is to keep the runs to the panels as short as possible to aid in diagnosing and maintainance.)

[Shez]

I have a "hacked" PC power supply that I've used to charge Lipo batteries for years. I get 12 and 5v from it. No issues.

[agrasyuk]

I've been studying it, and I think I will end up going to a quality PC PSU.

 

John, this only makes sence. PSUs are abundant, chances are you already have a few laying around. if not plenty of free old PCs available on craigslist to get one from. And even not the best quality generic oem models will still be providing plenty clean power for our needs.

Good thought on the toggle breakers too. Will make nice power distribution panel , you can have number of isolated power buses too that way . i have something like that already sketched out for my pit, ,also houses PC power and reset buttons , room and flood lights etc.

[Warhog]

I think you made an excellent decision. PSU's from PC's are fabulous. I have a Corsair 800 watt unit for my pit as well as several other no name PSU's and they all put out nice clean regulated power and they all have short circuit protection. I've even used one for a second bench PSU to test/panels circuits.

 

You probably saw this pic before. Its just a PSU from a PC I scrounged. I just fancied it up with some displays and a variety pf connectors. Thats an old pic during it's construction. Its all done now and it is so nice to use.

 

https://farm1.staticflickr.com/762/23379567756_64a3555642_b.jpg' alt='23379567756_64a3555642_b.jpg'>Desktop PSU by John Wall, on Flickr[/img]

 

However, even though you can get three flavors of voltage from these things I'm planning on using several PSU's. One for the back-lighting and one for all of the other cockpit parts. I have concerns about PWM for the backlighting having adverse effects on the other components. In response, I'm isolating the backlighting from everything else by providing it with its own PSU.

 

John