# Thread: Power my setup. Questions on Inverters!

1. ## Power my setup. Questions on Inverters!

Ok, I have been going back and forth on how to power all the 5V devices I have. I have so many USB hubs and 6 KVMP switches which require 5V power also. My idea was to buy a sine wave inverter and call it a day. BadMopar suggested a 12V to 5V device that I guess reduces 12V to 5V, but I am scared that if it were to malfunction, everything connected to it will die. So I figured a sine wave inverter coupled with a surge protector is easier for me.

Thing is, I do not know what power amount to buy, or how to calculate what I need.

There are three 7 port USB hubs. That equals 5V 4.5 amps.
Then a Ehternet Switch. That equals 5V 2.0 amps.
An Access Point. Thats 5V 2.6 amps.
Then 6 KVMP switches. Thats 5V 16 amps.

So thats a total of 5V 26 amps. How do I calculate what inverter I need?

2. if anything malfunctions, the devices it is connected to won't work-- whether thats your opus, or carpc...

i also vote for a 12v-to-5v converter.. i think it will be less trouble some then adding a inverter which is even more conversions, and possibilities for trouble..

from what i have seen before, you should be looking for a switching regulator-- this will reduce the amount of heat that the converter puts out(many converters get rid of the extra voltage in the form of heat), and allow it to run for longer(the advantage here is that while it still switches like a inverter, it can do it at a much higher freq. then a inverter, giving you less chance of audible noise.)..

3. If it helps:
watts = volts X amps = 80w

4. Ditto.

And why have and inverter to feed AC USB supplies?
The inverter fails and.....?

(5x26A = 130W. Add AC-DC conversion & inefficiency - hence a 300W inverter; 150W is too small.)

5. Originally Posted by soundman98
if anything malfunctions, the devices it is connected to won't work-- whether thats your opus, or carpc...

i also vote for a 12v-to-5v converter.. i think it will be less trouble some then adding a inverter which is even more conversions, and possibilities for trouble..

from what i have seen before, you should be looking for a switching regulator-- this will reduce the amount of heat that the converter puts out(many converters get rid of the extra voltage in the form of heat), and allow it to run for longer(the advantage here is that while it still switches like a inverter, it can do it at a much higher freq. then a inverter, giving you less chance of audible noise.)..
Well I would connect some of this stuff to the OPUS, but for some odd reason the OPUS will make the PC get stuck at BIOS. Now once I power the hubs on seperate power that is not running through the PSU, I have no issues with BIOS.

Well I know in the past I used inverters with a USB Hub and the Hubs keot dying, but it wasnt a sine wave inverter, just some cheapy I bought.

What is a switching regulator? That was another question, when these conversion devices step down to 5V, I know that heat builds up, but if unregulated power is going in, isnt that what is coming out also? So wouldnt I need to provide 12V regulated power?

Doing some reading, I have read that sine wave inverters have little or no noise at all. I dont know if its true though, but a lot of people are saying that.

My only concern is that the inverter, especially a sine wave, will provide regulated power. Will the converter do that?

Originally Posted by sharkzone
If it helps:
watts = volts X amps = 80w
Thank you for that.

Originally Posted by OldSpark
Ditto.

And why have and inverter to feed AC USB supplies?
The inverter fails and.....?

(5x26A = 130W. Add AC-DC conversion & inefficiency - hence a 300W inverter; 150W is too small.)
Thanx for breaking out the numbers for me. I was actually eyeing a 300W inverter. I have always know inverters to be very inefficient.

Now when calculating this out, should I be using what the input voltage on the adapter is, or the out put?

Also for these conversion devices, what happens if you over cool them, wouldnt that warm its power step down?

6. A switching regulator efficiently converts from one voltage to another (downward).
There are switching and linear regulators.
Linear regulators "burn" the "extra volts".
Switching regulators use "witchcraft" to be much more efficient.

I've had a ton of luck with this power supply: http://www.jameco.com/webapp/wcs/sto...0001_212549_-1

It is what powers all of my 24/7 5 volt equipment. It's been on 24/7 for 4 months. Never had a problem.

A couple of those should power everything you need. Whats also cool is the voltage is slightly adjustable. So you can control exactly what voltage is coming out. This sounds more like a solution than the Opus.

7. Originally Posted by PaulF
A switching regulator efficiently converts from one voltage to another (downward).
There are switching and linear regulators.
Linear regulators "burn" the "extra volts".
Switching regulators use "witchcraft" to be much more efficient.

I've had a ton of luck with this power supply: http://www.jameco.com/webapp/wcs/sto...0001_212549_-1

It is what powers all of my 24/7 5 volt equipment. It's been on 24/7 for 4 months. Never had a problem.

A couple of those should power everything you need. Whats also cool is the voltage is slightly adjustable. So you can control exactly what voltage is coming out. This sounds more like a solution than the Opus.
You know, I have seen these before, but never really looked into them. This may actually be the best way to go. The Linear regulators scare me to h3ll. The inverters I would love to avoid. So it looks like the switching regulator would be the best option. It sucks that I cant buy one with a 5V 20 to 30 amp output. It seems all of those require 36 volts and up. So I guess I will get 3 of these to get the 30 amps I need.

How big is the one you bought? Compared to the M4-ATX and the OPUS 320?

8. PS - Maybe a hacked PC supply for 5V @ 20A or more?
PPS - though at the price of PaulF's link... IMO 10A for \$32 is good.

Geez HiJack, you reckon my answers are complex - what about your questions?! (They actually scope a lot! Though PaulF summed beautifully - with a great tip too!)

As to "numbers", you want the INPUT power for all loads, and the OUTPUT power your supply is capable of.
Conversions have inefficiencies. And these vary. I usually add 20% or maybe 30% to conversion max (continuous) outputs if I don't have their max input figures.
Or I use their (input) fuse rating as a guide.
But both can vary wildly from reality if used for multiple devices.

EG - a 10A fuse means 80W is designed for minimum 8V operation, [email protected]; [email protected] or 160W if designed for a max of 16V.
BUT - that 10A fuse may be for a 80W "constant power" supply (eg; HIDs) which is normally ~5.5A near normal 14V. But then the load is always (say) 80W so you don't have worry about its voltage/current relationship. (Ah - they beauty of dealing with "constant power" devices. Except when figuring what fuse and power cable to use!)
EG - power conversion - an 80% efficient amplifier or dc-ac converter, or a 95% efficient dc-dc converter; or a 40mW resistor-fed LED that "draws" nearly 300mW (ie, 15% efficient)?

Remember - the inefficiency is usually heat. Its power is P=VI where V or I are the "lost" quantities.
Cooling prolongs life and cooling can improve efficiency (because of less resistance etc).
If cooling prevents damage, then it is required (eg, heatsinks, fans, car radiators).
Since cooling reduces wire etc resistance, there should be less heat (P = heat = IxIxR from P=VI & that V=IR hence V=I/R).
But cooling can cause other inefficiencies, though I doubt that in this type of situation - ie, I can't think of anything other than battery issues)

As to the rest - PaulF's excellent reply sums it up.
But since I started this before he replied ( !!)
So, included for reference and bit buckets...

This will be long, but I'm trying to break it all down, cover some basics (to be certain), so please bear with me. (And yes - I still love you, but I specifically wrote "bear" with me, not "bare with me".)
Also, I'll try "exec mode" of writing - first "heading" line is the basic answer or summary.
Later lines become less important wrt giving "the answer", but provide further explanation or detail. Or they can provide examples & trivia.
GO TO NEXT heading when too complex or enough is enough!
And [ square brackets ] usually mean "real pedantic, but I'm preventing later objectors that know otherwise" etc, though sometimes they enclose nested brackets [(maybe (too) many (other brackets) get confusing)].
Normally I'd use more inter-line breaks (between indirect sentences) and double line breaks between "real blocks", but to save space it's been crushed up. (Yes - I often use a hierarchy - full-stop & continue, full stop & new line; full-stop and blank line - three levels grouping.)

Switching Regulator: switches dc on/off to convert voltage.
More detail: Only AC transforms, hence convert DC to on-off DC which is AC (by definition and behavior).
SMPS (Switched Mode Power Supplies) are Switching....
SMPS (switching) is used in all step-up DC-DC converters, and now in many step-down DC and AC-DC converters.
[Ped: An ac-ac converter is a transformer. Ignoring (minor) inefficiency, power IN equals power OUT. So if 120V 10A in and 12V out, that's 100A out. (ie 1200W in = 1200W out. P = VI; Watts - Volts time Amps.]
The alternative to (step down) switching is Linear - eg, resistors, transistor circuits etc. But with them, at best current in = current out & hence inefficient. EG 120V 10A in = 12V 10A out; so 1200W in = 120W out. The Linear converter generates (1200-120=) 1080W heat because it "drops" or burns 108V at 10A. (Burns (C)PaulF 2010.)

"sine wave inverters have little or no noise at all". There output should be pure sine which - like DC - has no (other) "noise".
But like most power conversion, outputs have varying noise in practice - from negligible to disgusting. And that can depend on the load characteristics (size, inductive, SMPS etc).
Inverters are - in simple terms - a dc-dc converter without the output rectification (ac-dc).

Trivial: Because dc-dc is switching (AC) there is noise. But this is "internal" and might not come out of the output (ie, pure DC or sinewave) and should be shielded from radiating out (EMI/EMC etc)). So all switching converters can cause (both types of) noise.

[ The "non-sinwave" inverters are "pseudo-sinewave". Instead of a pure (smooth) sinewave, they approximate it using 2 stepped voltage levels (either side of zero volts 0V).
This "blocky" sharp-edged sinewave can be unfriendly to loads. It can overheat load input components (in their PSU).
Technically, the squarish output is a pure sinewave with lots of harmonics - sinewaves at higher frequencies for which the 50Hz or 60Hz load-PSU may not be designed for. Filter out those harmonics and they'll be ok. Harmonics are multiples of the "fundumental" frequency - eg, 2x60, 3x60, 4x60 etc = 120, 180, 240Hz etc. (Hence those noise frequencies...) ]

"will provide regulated power": All converters usually provide regulated power - ie, designed to maintain a certain voltage output irrespective of load current, load type, and input voltage.
How well they do this depends on their design (specs).
dc-dc & dc-ac can both suffer regulation problems.
dc-ac inverters are more prone to regulation problems due to bigger load variations - ie, phase angles, harmonics, inductive spikes (motors etc)....
dc outputs merely have to regulate voltage (as it changes with current load) since there are no output/load inductance, capacitance or frequencies involved. In theory that is...

"inverters (are) very inefficient: No.... they can be 90% or better, but most are only about 85% at best.
And that is at a certain output load.
Higher or lower than that and the efficiency drops.
And inverters (like dc-dc converters) always have some "idling current" - they still consume power just sitting there with no load. (Because they have whatever control electronics - circuit or uPCs or PIC etc.)
But idling power should be very low - maybe 1W or less - thanks to modern low power electronics. Some use to be tens of Watts.
Idling power may be insignificant when powering a 100W load etc, but if sitting on a battery in standby mode for hours....
Hence "standby" consumption - the power/current a dc-dc or dc-ac device consumes just sitting and waiting.
Standby power might be much less than "idling" power/current. VIZ - a low power supervisory pr monitoring circuit senses when conversion is needed and it starts up the "high power" converter...

"inverters (are) very inefficient - Part 2: No - they just add an extra inefficiency that is missing in the dc-dc converter.
They both have the same dc-ac inefficiency [ped: in principle, but that depends on design...] but the internal dc-dc converters ac-dc inefficiency is much less than the inverters external ac-dc efficiencies (eh, plug packs).

Did anyone read this line? (LOL)
(Maybe next time I'll add pre-planning to the exec mode!)

9. Haha oldspark, I read the whole response. I enjoyed the copyright in my name too.
I know you're always there when crazy details are needed.

Hijack,
Slow down there... I doubt you need 30 amps.

First, why do you need both an access point and an ethernet switch? Why not a wireless router with a 4 port switch built in? That would save space, wiring, and power. Unless of course you need more ports...

Regardless, the adapter may say 2.6 amps. I highly doubt the device is using that though. Check it with a multimeter. It may have been cheaper for them to just throw in a generic 2.6 amp adapter than the 1.0 that was necessary. Or they may have wanted to give some extra room for any additional overhead.

Really, check the given INPUT values on the devices themselves. Check them with a multimeter on the 5v side if necessary.

I HIGHLY doubt the KVMP switches use 2.6 amps each! They're maybe a switch, buttons, LEDs and possibly a microcontroller. I doubt they even use 500mA!

----
These switching regulators are actually bigger than the M4. But stacking them isn't a problem. They're enclosed. They don't generate much heat. I mean I wouldn't completely enclose them though haha.
Dimensions (H x L x W): 1.5 in x 6.25 in x 3.8 in.

10. [QUOTE=PaulF;1414675
Really, check the given INPUT values on the devices themselves. Check them with a multimeter on the 5v side if necessary.

I HIGHLY doubt the KVMP switches use 2.6 amps each! They're maybe a switch, buttons, LEDs and possibly a microcontroller. I doubt they even use 500mA![/QUOTE]

all of the 2-4 computer kvm's i have worked with have been able to be powered through the usb/vga/ps2 port-so they definitely don't take more then about 500ma..

though, for the usb hubs, i think you should still plan for at least 3a-- not all devices will consume the full 500ma usb ports are speced for, but it is better to have a little wiggle room..

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