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ExtraCredit1 24th November 2012 02:59 AM

Convert mini Pre-amp from AC to DC power
 
hey guys I have this mini Pre-amp I want to use in my portable speaker system but it will not work with DC power source.

Anyway to modify it to work on DC?

It said only AC on the description but I figured I would try it.

P7-MINI Preamplifier Board Top Pre-AMP Headphone DIY KIT FOR MX50 L20 L6 NE5532 | eBay

Thanks!!
Mike

sofaspud 24th November 2012 06:42 AM

The preamp itself runs from regulated +12 & -12 VDC.
The extent of power supply mods depends on the main energy source.

AndrewT 24th November 2012 09:57 AM

Remove or short the To92 regulators.

A pair of 12V batteries.

6 series connected lead acid, or 10 series connected Nicad, or 10 series connected Nimh, etc.

ExtraCredit1 24th November 2012 04:42 PM

Quote:

Originally Posted by sofaspud (Post 3254001)
The preamp itself runs from regulated +12 & -12 VDC.
The extent of power supply mods depends on the main energy source.


The manufacture says AC and I hooked up DC and it would not work.

ExtraCredit1 24th November 2012 04:44 PM

Quote:

Originally Posted by AndrewT (Post 3254140)
Remove or short the To92 regulators.

A pair of 12V batteries.

6 series connected lead acid, or 10 series connected Nicad, or 10 series connected Nimh, etc.


OK I guess this makes sense, so I don't need the regulators?

I have a +12 0 -12 DC power source.

ExtraCredit1 24th November 2012 04:49 PM

when you say short them or remove them how would I short them? they have 3 terminals. which of the 3 would I short?

MP

sofaspud 24th November 2012 07:03 PM

Remove the 2 regulators and solder the new power supply wires where the regulator Output and Ground pins were. Refer to the datasheets; the 2 regs have different pinouts.

ExtraCredit1 24th November 2012 07:32 PM

Quote:

Originally Posted by sofaspud (Post 3254709)
Remove the 2 regulators and solder the new power supply wires where the regulator Output and Ground pins were. Refer to the datasheets; the 2 regs have different pinouts.


K, thanks!! Just to make sure I get it, I remove both regulators completely then feed my power source to the output pin of where the regulator was? put +12 and ground on one and -12 and ground on the output pin of the other regulator?

So the power comes in and goes to the regulator then goes to the op-amp? by doing the above I am bypassing the regulator and sending power directly to the op-amp?

Mike

sofaspud 24th November 2012 07:37 PM

yes and yes

nigelwright7557 24th November 2012 11:06 PM

Quote:

Originally Posted by ExtraCredit1 (Post 3254524)
The manufacture says AC and I hooked up DC and it would not work.

It could be the AC adaptor is providing positive and negative voltages and simply plugging in a single phase DC supply wont work.


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