ausppc
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Re: tweet about psu inefficiency...

Sat Apr 21, 2012 10:18 pm

http://twitter.com/#!/abishurp.....7139101696

What would it take to eliminate or at least reduce wasted power?

Chris.Rowland
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Re: tweet about psu inefficiency...

Sat Apr 21, 2012 10:19 pm

Turn it off.

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Gert van Loo
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Re: tweet about psu inefficiency...

Sat Apr 21, 2012 10:30 pm

Replace the regulators with switched mode ones.

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scep
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Re: tweet about psu inefficiency...

Sat Apr 21, 2012 10:51 pm

The waste is about £2.74 per year (say 15p/KWh).

=About 2 litres of petrol.

=About 20 miles in the car.

So walk half a mile a week instead of taking the car - that should do it

andri
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Re: tweet about psu inefficiency...

Sun Apr 22, 2012 7:30 am

Chris Rowland said:


Turn it off.


LOL

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rew
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Re: tweet about psu inefficiency...

Sun Apr 22, 2012 9:09 am

When he says "lost power in the PSU" i htink he means in the 230->5V adapter.

After that, there is a significant loss in the 3.3V regulator. Pete claims 800mW disspation in the schematic. That would mean almost 500mA at 3.3V. A switching regulator on the GPIO adjusted for "just over 3.3V" might alleviate this a bit.

I suspect that the big 3.3V consumer is the LAN chip. So a model A will use less power and lose less in the regulator.
Check out our raspberry pi addons: https://www.bitwizard.nl/shop/

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Burngate
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Re: tweet about psu inefficiency...

Sun Apr 22, 2012 9:40 am

90 Wh, half lost in the PSU. But there's also another ~10% lost between the generator and the PSU, and upwards of 30% lost in the generator itself - not counting the inefficiency of the original plant-to-coal (or gas) conversion, and the photosynthesis losses in the plant.

So Solar panels would be a good idea.

ausppc
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Re: tweet about psu inefficiency...

Sun Apr 22, 2012 7:44 pm

re: solar - that gave me pause to check out the purported xo-3 OLPC and it's hand cranked and solar powering options.  That's got me thinking along the lines of foot cranked devices like bicycles, sewing machines and spinning wheels...  Never tried computing on pedal power - makes me wonder if it'd impede problem solving...

Helpme1986
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Re: tweet about psu inefficiency...

Mon Apr 23, 2012 10:01 am

Im using an external battery pack to power mine which is charged by the TV when its on, not sure if thats more efficient or not (but it did cost me £25 so will years to get my money back on the loss a standard PSU gives)

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abishur
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Re: tweet about psu inefficiency...

Mon Apr 23, 2012 12:22 pm

To be fair, my "half" claim was grabbed mostly out of the air based off what I was seeing and the amount of power I was expecting to be drawn by the r-pi.  I didn't actually do much in the way of math to get a real percentage

(but for the record I was referring to the 120V->5V conversion, and someone has claimed that the kill-a-watt is inaccurate on low power draw, but I've yet to see any proof for that except a forum post by some random guy)
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john_wage
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Re: tweet about psu inefficiency...

Mon Apr 23, 2012 5:27 pm

What would it take to reduce waste power in your PSU?

A better (more expensive) PSU!

What would it take to reduce even further?

Even better (even more expensive) PSU.





These steps can be repeated until you reach your budget limit for a 5V DC power supply.

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rgmward
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Re: tweet about psu inefficiency...

Tue Apr 24, 2012 9:11 am

I remember reading an article a few years ago about how the average UK home could save a lot of money in wasted electricity if the houses were wired with 2 electrical circuits - standard 240v and 9v - so that we would only have the 1 step down transformer.

time has moved on since then, and the 2v usb connector has become a defacto standard for chargers.    perhaps it is time for usb ports installed as standard in homes in a few key locations, so that we can kill off the wall-warts!

this has given me an interesting idea during my current home improvements  i wonder what size transformer i can install in the garage and wire to key locations where i want to run a raspberry and charge my phone )

Phil Spiegel
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Re: tweet about psu inefficiency...

Tue Apr 24, 2012 10:00 am



I remember reading an article a few years ago about how the average UK home could save a lot of money in wasted electricity if the houses were wired with 2 electrical circuits – standard 240v and 9v – so that we would only have the 1 step down transformer.

time has moved on since then, and the 2v usb connector


(2V????)

For the same reasons as the National Grid uses high voltage transmisson, with local step down transformers; as has already been discussed here with regard to losses within short power leads from SMPS to Pi: distribution at low voltage within a house would probably be inefficient - as would a traditional 50Hz step-down transformer: so a series of modern energy efficient SMPS, used as required, to appropriate voltages - and my railway uses 4x 18Vdc @0-3.5A, 16Vac @0-5A, 12Vdc@0-4A and 5V@1A, for example shows that imposing builders fitting a single value low voltage socket would be inapproriate and inefficient ... and trake a long time to recover the cost!!!

I also find myself wondering how these 'statisitical comparison' houses are found: apparently using only 500W valve TVs and tungsten bulb lighting with no insulation..

TVs have had 1W standby for years, and 'equipment left on' is usefully heating the house in winter - resulting in less heat requirement from 'heaters' - assuming the home is well insulated.  [MOST USEFUL would be the adoption of DYNAMIC DEMAND CONTROL - with fridges, freezers and underfloor heating etc using power when the frequency rises, but deferring consumption when the frequency falls, under load]


this has given me an interesting idea during my current home improvements  i wonder what size transformer i can install in the garage and wire to key locations where i want to run a raspberry and charge my phone )


We have 2kW and 1.2kW Grid-connected inverters in our garage, running off the solar panels on our roof.  But the wrong place for a lump of copper transformer!

The lower currents required by LED lighting might make the low-voltage-ring more viable (buit copper prices are high!) - but these are usually based around a well-regulated 12V.


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rgmward
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Re: tweet about psu inefficiency...

Tue Apr 24, 2012 12:00 pm

Phil Spiegel said:




I remember reading an article a few years ago about how the average UK home could save a lot of money in wasted electricity if the houses were wired with 2 electrical circuits – standard 240v and 9v – so that we would only have the 1 step down transformer.

time has moved on since then, and the 2v usb connector


(2V????)



Sorry - pressed the wrong key - i obviously meant 5v.

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