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Old 21st January 2012, 11:02 PM   #1901
Turbon is offline Turbon  Sweden
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Quote:
Originally Posted by raspunsen View Post
Seems like you have given me the answer to my problem and i forgot to check it at the time... Shame on me. Guess i just assumed U5 was dead because the solder joints seemed ok.
I just heated the 3 joints of U5 and it's working fine now.
I still have the old resistors. I don't mind having this behaviour, it's a sign i need to recharge it. It's just that 1 hour seems like too short. I was expecting more.

Edit: @jschristian44: My batteries are Philips. Not the cheap kind...
As I see it there is no problem with any brand of battaries - it's a design issue. The design does work in an ideal world which we are not part of.

Brgds
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Old 21st January 2012, 11:30 PM   #1902
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If i manage to get some more running time from these i will not even consider changing the batteries or the resistors. I can live with that. If i can't, i'll try something else. Thought Philips would be a nice brand of batteries though.

By the way, how should we charge the batteries, with amp on or off?
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Old 22nd January 2012, 03:14 AM   #1903
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Manage to complete my first O2 portable case and it work on the first try (no battery wet). I'm listening to it while I'm typing this message and it sound really good. This was an easy build specially due to all the well documented process. "Chapeau" to NwAvGuy for this amazing amplifier. Thanks! (I'll be building the desktop model now).
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Old 22nd January 2012, 06:52 AM   #1904
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Perhaps the most important characteristic of the BOM batteries is their 8.4V output, as opposed to the more common 7.2V. The difference will affect run time.
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Old 22nd January 2012, 09:45 AM   #1905
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@sofaspud - afaik, 9v PP3 NiMH rechargables are either 7 cell, giving 8.4 volts, or 8 cell, giving 9.6 volts when fully charged.
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Old 22nd January 2012, 09:52 AM   #1906
Turbon is offline Turbon  Sweden
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Quote:
Originally Posted by raspunsen View Post
If i manage to get some more running time from these i will not even consider changing the batteries or the resistors. I can live with that. If i can't, i'll try something else. Thought Philips would be a nice brand of batteries though.

By the way, how should we charge the batteries, with amp on or off?
As long as your AC transformer can handle the load you can charge the batteries either way, on or off.

Brgds
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Old 22nd January 2012, 10:05 AM   #1907
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Left the amp charging the batteries all night and measured them with a dmm. BT1 is giving 9.77v and BT2 is giving 9.31v. I don't have a clue if this is normal.
Anyway, they are Philips Rechargeable accu 8.4V NiMH, 170mAh. They seem within spec regarding the BOM.
Any thoughts on this?
Thx for the explanation Turbon.
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Old 22nd January 2012, 10:39 AM   #1908
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NwAvGuy does include a brief on recommended batteries in the O2 details, though I might have imagined 7.2V types were more common.
raspunsen, I'm currently using the type shown below. With my Grado SR80s they'll run for only a few hours at most before needing a recharge.
I have a mod in the works that addresses run time no matter what PP3 is used.
Attached Images
File Type: png 9V-NH22.png (34.5 KB, 296 views)
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Old 22nd January 2012, 11:39 AM   #1909
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OK, PP3 NiMH batteries are available in 7.2, 8.4 and 9.6 voltages.

Given the number of 9.6v PP3 batteries available, why choose a 7.2v?

e.g. Powerex 200 mAH 9.6V PP3 Rechargeable Battery from mahaenergy.co.uk

and VTE220PP3

Last edited by greenalien; 22nd January 2012 at 11:46 AM.
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Old 22nd January 2012, 01:22 PM   #1910
Limp is offline Limp  Norway
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Quote:
Originally Posted by greenalien View Post
OK, PP3 NiMH batteries are available in 7.2, 8.4 and 9.6 voltages.

Given the number of 9.6v PP3 batteries available, why choose a 7.2v?

e.g. Powerex 200 mAH 9.6V PP3 Rechargeable Battery from mahaenergy.co.uk

and VTE220PP3
Or even better

2 Tenergy 9V 250mAh NiMH Rechargeable Battery | eBay
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