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Class D Switching Power Amplifiers and Power D/A conversion

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Old 18th July 2011, 10:25 PM   #831
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Originally Posted by kroem View Post
I'm planning to run this of a 8 pack AA batteries - any chance I will kill it? (ie. go over 14V?)
I am running my A+ from 10 AA NiMh cels without a hitch. The measured voltage across the pack fully charged was a little over 14V but this dropped away to under 14V on switch-on.

Tim.
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Old 29th July 2011, 06:13 PM   #832
craler is offline craler  Sweden
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I can't seem to get my Lepai amps to output any sound. I'm using a 12V SLA battery as power supply. And when I power on the amp the diodes are looping from 100% on to maybe 75% and back to 100%. Is it supposed to do that?

When I power them with a small 9V battery instead, the light from the diodes are constant but still no sound output. I've tried both the RCA and MP3 inputs and three different Lepai amps, all the same problem. I heard that you are supposed to hear o click or pop when you put it on, I don't get that, it's dead silent.

What do you think might be the problem?
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Old 29th July 2011, 06:24 PM   #833
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Are you sure that you have powered them with the positive to the centre pin? The Lepai amps have no protection against reverse polarity. Reverse polarity destroys the Tripath chip immediately.
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Old 29th July 2011, 06:27 PM   #834
craler is offline craler  Sweden
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Yea, I'm definitely sure, tested it many many times with my multimeter.
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Old 29th July 2011, 06:49 PM   #835
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Well, all I can say is you should return what has failed to the sellers. You don't need me to say this!

The community would like to hear how you get on.

Regards,

T.
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Old 29th July 2011, 08:07 PM   #836
nige838 is offline nige838  United States
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Quote:
Originally Posted by kroem View Post
Any chance of getting a picture?



I am unable(/an idiot) to read those layouts, would it be possible to help out a noob and show a real picture?

I'm planning to run this of a 8 pack AA batteries - any chance I will kill it? (ie. go over 14V?)
8 AAs is 8 x 1.5 = 12volts. Your fine.
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Old 29th July 2011, 08:42 PM   #837
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Originally Posted by nige838 View Post
8 AAs is 8 x 1.5 = 12volts. Your fine.
Technically that's only open voltage of standard alkalines. Under load they're around 1.2V each, so you'd actually need 10 in series to get you desired 12V operating voltage.

(It's also why NiMH batteries work fine as replacements even though their nominal voltage is only 1.2V. They maintain that voltage under load.)

Last edited by Saturnus; 29th July 2011 at 08:48 PM.
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Old 30th July 2011, 01:52 PM   #838
nige838 is offline nige838  United States
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Originally Posted by Saturnus View Post
Technically that's only open voltage of standard alkalines. Under load they're around 1.2V each, so you'd actually need 10 in series to get you desired 12V operating voltage.

(It's also why NiMH batteries work fine as replacements even though their nominal voltage is only 1.2V. They maintain that voltage under load.)
Yes, this is all true, but if the IC sees 15 volts for even a second, then it's all over...
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Old 30th July 2011, 02:10 PM   #839
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Originally Posted by nige838 View Post
Yes, this is all true, but if the IC sees 15 volts for even a second, then it's all over...
Nope. Absolute maximum rating of the chip is 16V. It should not be operated under that voltage but it will survive, in fact, I had a TA2020 survive 19.2V as well.

Maximum operating voltage is 14.6V, btw.
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Old 7th August 2011, 01:01 AM   #840
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Originally Posted by candoumi View Post
For those interested, this is a picture of the newest board (dual opamp and tone bypass).

Click the image to open in full size.

There is no component underneath.
Thanks for the photo. Has the newest board with tone bypass been measured?

So now we are just left with the minor tweaks - power supply capacitors, output inductors, resistors and capacitors (replacing with better quality parts)?
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