OK IS MY CALCULATIONS CORRECT?

[ElideN]

ALRIGHT ALRIGHT ALRIGHT, FINAL CONCLUSION TO ALL CALCULATIONS USING AN ANKER OR ORICO 3.0 10 PORT HUB AND USB ERUPTER.


Rating on ac adapter/hub specifications:
Input: 120v 1.2a wall to
Output: 12volts 4000mA

OHMS-WATTS LAW: i = p / v

2.5w / 12v = 200mA


Usb erupter uses 200mA

the 10x erupters would use 12 volts, about 1.9volt each

total current = 2 A


am i correct?

[kuusj98]

Why not....

[ElideN]

i thought so, some guy on ebay was worried that his usb erupters would get fried.

he says

How much current will this hub handle? 10 miners will consume 5 Amps, and would burn up most hubs; even smaller ones.

Block Erupters specs state it uses they 500mA (.5A) that's is 5 total amps with 10 units. If the hub is not rated for 5 amps it will eventually fail, and that will not work for me. If you can get the manufacturers spec that would make me frrl better.
And your calculations should look like this 2.5 W=.5A/5V, the Erupters operate using 5 volts
Thanks

how did this user come up with this?

[mufa23]

No, I don't think so... but you're a little hard to follow and I had to keep re-reading it. What I gathered though is that you want to know if a certain USB hub will be powerful enough to run 10 USB Erupters? Could you provide a link to the USB hub you plan on purchasing?

EDIT: And if memory serves me correctly, USB is always 5v.

[ElideN]

www.ebay.com/itm/321168175159

[mufa23]

Ah, check out this dude. I just found a thread listing all sorts of USB hubs for Erupters. Check it out --> https://bitcointalk.org/index.php?topic=253749.0

[ElideN]

Ah, check out this dude. I just found a thread listing all sorts of USB hubs for Erupters. Check it out --> https://bitcointalk.org/index.php?topic=253749.0

You sir are awesome...

[mufa23]

show your math works!

According to their website, this unit runs off a 12v/4a power adapter.

12volts X 4amps = 48watts

Now since USB uses 5v, this allows more amps but using the same wattage.

48watts / 5volts = 9.6amps

This means that there is a total of 9.6amps that can be pulled from all 10 USB ports. Now since an Erupter uses 200mA, that means that 10 of them will use a total of 2 Amps of the 9.6 Amps available. This thead over here confirms it --> https://bitcointalk.org/index.php?topic=253749.0

We can also run this equation the other way around to see how many watts each Erupter will use. Since we know that each one uses 200mA and will run at 5volts, we can do the math to figure out how much watts each will use.

5v X 0.2a = 1w

A since unit will use 1 watt of power. So with ten Erupters, you will use a total of 10 watts of power. And the first equation above shows us that this USB hub has a maximum of 48 watts available. You will only be using 10 watts.

So this USB hub should work great for ten USB Erupters. I hope this helped some.

[cp1]

Output: 12volts 4000mA
2.5w / 12v = 200mA
Usb erupter uses 200mA
the 10x erupters would use 12 volts, about 1.9volt each
total current = 2 A
am i correct?

The erupters use 5V, not 1.9V -- volts don't get split up; amps do.  You're also assuming the 12V gets converted to 5V at 100% efficiency, which is probably not true, but I don't know what kind of regulation they use.

[mufa23]

You're also assuming the 12V gets converted to 5V at 100% efficiency, which is probably not true...

This guy has it right. Generally speaking, it will be about 80% efficient.

Power Adapter: 12v X 4a = 48w

USB Hub: 5v X 9.6a = 48

USB Hub at 80% = 5v X 7.68a = 38.4w

Realistically, you'll roughly have ~38 watts of power for any USB devices you plug in. But in a perfect world, it would be 48 watts. However, it's still enough power for all ten Erupters with plenty of power to spare.

[ElideN]

Output: 12volts 4000mA
2.5w / 12v = 200mA
Usb erupter uses 200mA
the 10x erupters would use 12 volts, about 1.9volt each
total current = 2 A
am i correct?

The erupters use 5V, not 1.9V -- volts don't get split up; amps do.  You're also assuming the 12V gets converted to 5V at 100% efficiency, which is probably not true, but I don't know what kind of regulation they use.

that was exactly what i was thinking 12 volts over the entire hub. been awhile with electronics.

[ElideN]

on amazon it say:

Plugs into standard USB port
Power Usage: 500-510 mA





on
bitcoinexaminer.org

Heat reduction: 560mA (emerald) -> 500-510mA (sapphire)





what is the difference?

[ElideN]

ok, lets assume the hub is rated at 4amp like it was stated.





but wouldn't .5ma x 10 = 5amp?





that would be over the rated 4amp. wouldn't that burn it out, if not eventually ruin the usb erupters?

[cp1]

But it's 4A @ 12V.  Which is 48W.  At 5V, 48W is almost 10A at 100% efficiency (not possible) -- at 80% efficiency it's around 8A (see mufa above)