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Old 20th June 2005, 06:38 AM   #1
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Default OPA549 on single supply

Hello !

Can anybody comment if the schematic for connecting the OPA549 on the single supply is correct ? If it is not please give me some advice how to make it right.

Cheers
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Old 20th June 2005, 08:00 AM   #2
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There's a few errors, look at your power supply connections. But more importantly why would you want to run with a single rail? You now have to use a coupling cap at both the input and output which isn't what I'd recommend for anything related to hifi. If you only have a 30-volts single rail you can also split it to 2x15 and settle on that.

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Old 20th June 2005, 09:01 AM   #3
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I have to put this amp in an guitar amp where I have only +30V DC. Can you tell me where are the errors at the power suply connection ?

Cheers
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Old 9th August 2005, 09:56 PM   #4
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When do you not have a negative supply. The V- conector go to GROUND.
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Old 9th August 2005, 10:16 PM   #5
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Hi bostjancek,

Yes, there are a few errors on your shematic.
The 4,700uf + 100nf caps are in series with the positive voltage rail (?!), they should be parallel from V+ to ground.
The input 2.2uf cap should be before the 47k cap.
And a suggestion: use a 4,700uf cap on the output, although not so important for a guitar amp.
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Old 9th August 2005, 11:52 PM   #6
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Quote:
Originally posted by carlosfm
Hi bostjancek,

Yes, there are a few errors on your shematic.
The 4,700uf + 100nf caps are in series with the positive voltage rail (?!), they should be parallel from V+ to ground.
The input 2.2uf cap should be before the 47k cap.
And a suggestion: use a 4,700uf cap on the output, although not so important for a guitar amp.

And... use a snuberized PSU ... I like the snubber that sound is more beautiful than the others schematics! I love your idea.

Thanks
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Old 10th August 2005, 12:18 AM   #7
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Quote:
Originally posted by mod_evil
And... use a snuberized PSU
You said that, not me.
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Old 10th August 2005, 11:58 PM   #8
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Default Re: OPA549 on single supply

Quote:
Originally posted by bostjancek

Can anybody comment if the schematic for connecting the OPA549 on the single supply is correct ? If it is not please give me some advice how to make it right.

One suggestion:

Try a different way for your virtual ground input connection. Increase the value of those resistors to something like 47K each, and don't connect that point directly to the + input, but through another 47K resistor. Then use a a 1uF capacitor from that middle resistor point to the V- rail. That should lower your ripple noise. Or use the parts used in the LM3886 datasheet for single supply application.

A single supply design has several flaws, the large output capacitor being the main one. So I don't think it will help much using a snubberized supply with it.


Carlos
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Old 12th September 2005, 02:05 PM   #9
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Thanks for your comments. I realy don't know where my head was when I drown the given schematic.

Cheers !
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