The Objective2 (O2) Headphone Amp DIY Project - Page 193 - diyAudio
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Old 25th January 2012, 08:28 PM   #1921
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Quote:
Originally Posted by jmwreck View Post
hello guys, I wanted to ask about this transformer: http://www.evernote.com/shard/s102/s...12874e98482e60

this is the one I have, if I assemble it, can I use it to power and charge my o2 ?

my concern is that I havent read VAC on the output

thanks

It will work fine if you wire it up for 20V (series). Your regulators may get a bit on the hot side but everything will operate within spec, so you're good to go.
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Old 25th January 2012, 11:58 PM   #1922
jmwreck is offline jmwreck  Philippines
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Quote:
Originally Posted by ethanolson View Post
It will work fine if you wire it up for 20V (series). Your regulators may get a bit on the hot side but everything will operate within spec, so you're good to go.
wow, thank you. there will be a voltage drop so it isnt exactly going to reach 20v. the "series" that you have mentioned is the same as the way it was shown on my link?
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Old 26th January 2012, 12:36 AM   #1923
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Originally Posted by MrSlim View Post
Describe what it sounds like if you can, one or both channels, was it plugged into AC or on battery, etc...
It sound very jagged, it happen to both channels and was on battery. This morning when I tested it without input, the headphone was silence for 1about 0 second, then a 'tub, tub.....' sound in interval about 0.5 second come.
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Old 26th January 2012, 12:46 AM   #1924
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Quote:
Originally Posted by jmwreck View Post
wow, thank you. there will be a voltage drop so it isnt exactly going to reach 20v. the "series" that you have mentioned is the same as the way it was shown on my link?
Yeah. Series wiring means that you're wiring one half of the transformer to feed the other... like how you stick D batteries end to end in a flashlight.

Here's a good link for it.
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Old 26th January 2012, 01:15 AM   #1925
jmwreck is offline jmwreck  Philippines
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Quote:
Originally Posted by ethanolson View Post
Yeah. Series wiring means that you're wiring one half of the transformer to feed the other... like how you stick D batteries end to end in a flashlight.

Here's a good link for it.
base on your link, i must be following the series on figure 1. which is just the same diagram on my link.
Click the image to open in full size.


however, if you refer to my link, it mentioned:

Electrical Specifications (@25C)
1. Maximum Power: 10.0VA
2. Input Voltage Series: 230VAC @ 50/60Hz, Parallel: 115VAC@ 50/60Hz
3. Output Voltage Series: 20.0V CT@ 0.5A, Parallel: 10.0V @ 1.0A
4. Voltage Regulation: 20% TYP @ full load to no load
5. Hipot: 3500VAC between primary to secondary and windings to core.


CT is center tapped right? am i going to follow the diagram on figure 2?

Click the image to open in full size.
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Old 26th January 2012, 02:55 AM   #1926
zeffa is offline zeffa  Australia
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Quote:
Originally Posted by coolhead View Post
It sound very jagged, it happen to both channels and was on battery. This morning when I tested it without input, the headphone was silence for 1about 0 second, then a 'tub, tub.....' sound in interval about 0.5 second come.
That sounds like the rapid clicking that happens when the battery is low. It should go away as soon as you plug the AC back in. This is what RocketScientist mentioned on his blog:

Quote:
CLICKING OR RAPID TURN ON/OFF: This indicates the amp is shutting down due to low batteries or some other power supply problem. If you are working from earlier documentation, R9 has been changed to 33K and R25 to 1.5M to help the amp stay off when it shuts down. But these are not critical changes. Either way the amp is no longer usable until the batteries are charged. You can consider the clicking a reminder to turn off the amp.
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Old 26th January 2012, 03:02 AM   #1927
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Ignore the center-tap option. It's not used for the O2.

Transformer Center Tap
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Old 26th January 2012, 03:26 AM   #1928
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Quote:
Originally Posted by zeffa View Post
That sounds like the rapid clicking that happens when the battery is low. It should go away as soon as you plug the AC back in. This is what RocketScientist mentioned on his blog:
ok, will try that once I reach home on Saturday, I am outside without the charger now.
How long it need to charge the battery if I am using a 75VA, 14Vac trans as input? I charge it 4 hour before I take it out, I think is not enough.
Thanks.
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Old 26th January 2012, 09:20 AM   #1929
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@qusp

You're right, it isn't really a valid criticism as such. I just found it funny that people were simultaneously declaring it subjectively wonderful and subjectively beaten by a CMOY. Even by Head-Fi standards, that is quite impressive division of opinion.
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Old 26th January 2012, 09:34 AM   #1930
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How long it need to charge the battery
NiMH batteries should be charged at around 10% of their rated capacity, i.e. around 20mA, so should take 10 hours to charge from flat. Charging them faster than this can overheat them. NiMH batteries generally need 4 - 5 full charge/discharge cycles before reaching their maximum capacity.
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