Power consumption of computer speakers - Page 3 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 4th October 2013, 05:26 AM   #21
diyAudio Member
 
availlyrics's Avatar
 
Join Date: May 2011
One has to calculate the real "environmental cost" (which is more & will be paid dearly by our future generations) as compared to just utility bills.

Back to the topic- I've seen cheaply built traffos having thermal runaway problems leading to burnt windings when not loaded or only secondary disconnected by switch as reported by Andrew T.
Also back in our college days during electrical eng. labs we used to draw eta curve (efficiency curve) for traffos using various dummy loads. The results were (if my memory serves me right) 50% to 95% efficiency under various load conditions.
__________________
Thanks,
availlyrics

Last edited by availlyrics; 4th October 2013 at 05:34 AM.
  Reply With Quote
Old 4th October 2013, 08:08 AM   #22
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
The printer also has a switch. So does the monitor. Both are soft touch and therefore leave the supplies running. So does the computer. And the TV, and. . .
We're probably not going to run all over the house unplugging everything.
Therefore I recommend upgrading the room wiring to switch off all outlets, except for the fridge.

P.S.
Here in the USA, the big green colored dual channel switch at Lowes is probably strong enough for this approach. It has survived my hot water heater. So far, with some of the ZuniDigital smart sticks and increasing the number of rooms that switch off completely, the average bill has decreased $43 monthly, despite the electric company raising the rates. The sturdy switches and smarts sticks paid off in 2 months.
Disconnecting is highly effective! Not much else is.
Found out that ceiling level insulation is ineffective, but roof level insulation is highly effective. Currently working on adapting climate controls to a zone system because the garage doesn't need air-conditioned while I'm asleep or out. Also investigating the windows, both the frame and panes to non-thermally-conductive materials instead of the aluminum and glass that are easily identifiable as errors.
When it comes right down to it, there's a LOT of easily identifiable errors that run up our bills.
They are individually small and very numerous. So, catching all those many little errors isn't easy.
__________________
Tools, Models & Software for DIYClipNipper boostLM1875 TurboPowerful TDA7293 kitTDA7294 pt2pt ♦ My post has opinion.

Last edited by danielwritesbac; 4th October 2013 at 08:11 AM.
  Reply With Quote
Old 5th October 2013, 05:24 PM   #23
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
The current consumption varies depending on the supply voltage.
for 230Vac supply ON=36mAac, OFF=35mAac ~8W
for 240Vac supply ON=65mAac, OFF=65mAac ~15W
for 250Vac supply ON=130mAac, OFF=135mAac ~34W
That's some dissipation for a 21.6VA transformer !
It does say "Made in China".
__________________
regards Andrew T.
  Reply With Quote
Old 5th October 2013, 05:39 PM   #24
dmills is offline dmills  United Kingdom
diyAudio Member
 
Join Date: Aug 2008
Location: High Wycombe
But at least in the UK domestic users pay for real power not apparent power, so the question then is how much of that 34VA is real and how much of that is purely reactive?

Most of that 34VA is **NOT** dissipation!

My betting is that only about 10% or so of that is real power, with the rest being reactive.

Regards, Dan.
  Reply With Quote
Old 5th October 2013, 05:56 PM   #25
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Good Question.
__________________
regards Andrew T.
  Reply With Quote
Old 5th October 2013, 08:02 PM   #26
KSTR is offline KSTR  Germany
diyAudio Member
 
KSTR's Avatar
 
Join Date: Jul 2007
Location: Central Berlin, Germany
Quote:
Originally Posted by AndrewT View Post
The current consumption varies depending on the supply voltage.
for 230Vac supply ON=36mAac, OFF=35mAac ~8W
for 240Vac supply ON=65mAac, OFF=65mAac ~15W
for 250Vac supply ON=130mAac, OFF=135mAac ~34W
That's some dissipation for a 21.6VA transformer !
It does say "Made in China".
These values are crazy, Andrew, that little tranny must be severly underwound.

FWIW a scope pic of a 230V/100VA type, China as well, from a consumer hifi. Test voltage was 250Vac, open secondaries. The transformer was humming audibly at this levels. While basically the idle current is inductive, once the core saturates inductivity decreases, making the current dissipating some real watts in the coil winding resistance while total power is some 10VA. The current peaks are not symmetric to the voltage zero crossings spaced 2 divs apart around the trigger.
Attached Images
File Type: gif 250Vac_open_sat.gif (20.3 KB, 91 views)
  Reply With Quote
Old 5th October 2013, 10:03 PM   #27
dmills is offline dmills  United Kingdom
diyAudio Member
 
Join Date: Aug 2008
Location: High Wycombe
Ignoring the iron losses (Not necassarily safe) the interesting question becomes, what is the DC winding resistance of the primary?

The copper losses in the unloaded case can then be approximated by I^2R where I is the rms magnetising current observed.

Regards, Dan.
  Reply With Quote
Old 6th October 2013, 09:03 AM   #28
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
The transformer is stamped as 230V.
It appears that DAN have selected a 230V transformer that is possibly not a universal 220/240Vac unit to save costs.
When used on UK's 240Vac which can vary from 226Vac to 254Vac, that the transformer has gone into saturation at the upper end of the working voltage range.
__________________
regards Andrew T.
  Reply With Quote
Old 9th October 2013, 06:42 PM   #29
diyAudio Member
 
mondogenerator's Avatar
 
Join Date: Sep 2009
Location: City Of Villans
Blog Entries: 1
Many times a 115VAC/230VAC, (or 120/240 for that matter) are exactly the same.

Its very common practice.

UK voltage is unlikely to be quoted as 230 VAC anymore, unless in error. 240-250VAC is the case nowadays.

Our voltage was only ever quoted as 230VAC to align with European AC, since we buy so much of it....

For what its worth, my mains voltage here dips to its lowest at 6am, at 240VAC. Mostly I get 245-255VAC.

Now IF the trafo is 60hz rated then perhaps......

And not forgetting power quality. Lots of harmonics in the mains doesn't help either. Maybe the trafo is rated at pure sine VAs (a joke here) or the core lams are naff steel, or badly insulated. I.e. Daft amounts of coreloss, even before copperloss is factored in.

Since you're measuring a high idle current with the secondary winding OC then it indicates significant iron loss, and NOT copperloss, and an inefficient core, bad lams etc.

Regards,

A trafo abuser in my 9-5
__________________
Every new piece of knowledge pushes something else out of my brain - Homer.....................Simpson

Last edited by mondogenerator; 9th October 2013 at 06:59 PM.
  Reply With Quote
Old 10th October 2013, 02:53 AM   #30
gootee is offline gootee  United States
diyAudio Member
 
Join Date: Nov 2006
Location: Indiana
Blog Entries: 1
Quote:
Originally Posted by availlyrics View Post
One has to calculate the real "environmental cost" (which is more & will be paid dearly by our future generations) as compared to just utility bills.
The "environmentalist cost" is much higher than that, and is mostly fraudulent waste, with a lot of waste heat dissipated orally, resulting in the only actual cause of any anthropomorphic global warming.
__________________
The electrolytic capacitors ARE the signal path: http://www.fullnet.com/~tomg/zoom3a_33kuF.jpg
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Calculating Current Consumption (USB Powered Speakers) FenderBender11 Chip Amps 20 12th March 2012 11:05 AM
Power consumption Viper_user Solid State 5 12th March 2012 10:41 AM
Power consumption Zanthus Full Range 10 19th September 2010 12:01 PM
power consumption tfrei Chip Amps 2 1st December 2007 10:34 PM
Cheap low power design for computer speakers haut Solid State 2 5th March 2004 04:47 AM


New To Site? Need Help?

All times are GMT. The time now is 11:13 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2