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Author Topic: Centre Negative DC Jack  (Read 2799 times)

flester

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Centre Negative DC Jack
« on: July 02, 2018, 09:20:23 AM »
I've been trying to work this out for myself but it's beaten me.

I have a few small amps which can run off a 9v battery, or a wall wart via a DC jack (which disconnects the battery). I want to change the DC jacks to be 'negative centre' so match my pedals so I can run the amp and pedals from the same supply. Any suggestions for wiring this?

Jazz P Bass

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Re: Centre Negative DC Jack
« Reply #1 on: July 03, 2018, 02:02:26 AM »
How about some info on the pedals?

Basically, you are looking at redesigning the power in jack.

flester

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Re: Centre Negative DC Jack
« Reply #2 on: July 03, 2018, 07:49:34 AM »
Pedals are Behringer delay, Behringer tremolo pan,  Danelectro Fab Overdrive, Mooer Shimverb.  Pedals all have centre negative jacks and use 9v. I know I need to reverse the leads from jack to board to use the external ps but not sure how to connect the internal battery.

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nosaj

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Re: Centre Negative DC Jack
« Reply #3 on: July 03, 2018, 09:20:29 AM »
Would it not be possible to make an adapter that crosses or flips th polarity?

I think I have made these before for other projects.

nosaj

nosaj

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Re: Centre Negative DC Jack
« Reply #4 on: July 03, 2018, 10:52:12 AM »

Jazz P Bass

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Re: Centre Negative DC Jack
« Reply #5 on: July 03, 2018, 12:21:00 PM »
Cool!

galaxiex

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Re: Centre Negative DC Jack
« Reply #6 on: July 03, 2018, 07:14:34 PM »
Nevermind they sell them
https://www.musiciansfriend.com/accessories/truetone-reverse-polarity-converter-for-1-spot
nosaj

Boy, I'd be marking THAT with some kind of bright orange or yellow tape....
Fear leads to Anger, Anger leads to Hate, Hate leads to Suffering.

nosaj

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Re: Centre Negative DC Jack
« Reply #7 on: July 03, 2018, 11:56:30 PM »
I would too but it's a hella lot easier than redesigning a pedal.

nosaj

flester

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Re: Centre Negative DC Jack
« Reply #8 on: July 10, 2018, 11:32:07 AM »
OK I think I've got it. Basically I need to reverse the polarity of all the leads connected to the DC jack.
https://goo.gl/images/awuayZ

Just to clarify, I will keep the pedals centre negative and convert my amps to be the same. That way all my pedals and battery amps can be powered by an effects power supply. Might also add diodes to the amps for reverse protection.

phatt

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Re: Centre Negative DC Jack
« Reply #9 on: July 11, 2018, 02:17:20 AM »
If???? ALL the amplifiers are battery powered ONLY,,
then yes it's simple to swap 2 wires inside the amp.
 
BUT!!!! :trouble :trouble

Most battery Amps come with the option of mains power as well as internal battery and some come with the 3rd option of wall wart power. The wiring system could be complicated for the novice.

Without circuits and specs for the Amp/Amps you are trying to power this is all guesswork.

I strongly advise the reverse polarity option cable mentioned by *Nosaj*.
And as *Galaxiex* mentioned Clearly marked as Reversed Polarity.

Your other problem is you will need a power supply that can deliver enough current to power the amp as well as all the pedals. :-X
Phil.

flester

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Re: Centre Negative DC Jack
« Reply #10 on: July 12, 2018, 04:02:34 AM »
They are amps I built myself with 9v battery or wall wart options. I believe I just need to change the wiring from centre pos to centre neg as shown in picture. I take the point about current requirements though. One of the amps uses an lm386 which which may not need much but another uses a Kemo 12w module so it may not work for that one.

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flester

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Re: Centre Negative DC Jack
« Reply #11 on: July 12, 2018, 05:30:17 AM »
This one draws 0.5A https://www.velleman.eu/products/view/?id=9181

And this one 0.8A
https://www.kemo-electronic.de/en/Light-Sound/Amplifier-Splitter/Modules/M032N-Amplifier-12-W-universal.php

I thought maybe the LM386 could go in my pedal board/box as it is pedal sized and plugs into an external speaker

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flester

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Re: Centre Negative DC Jack
« Reply #12 on: August 14, 2018, 03:46:09 PM »
Heres what I came up with. The bundle of 6x AA rechargeables to the right of the pedal box has a centre -ve  lead supplying pedals, and a centre +ve  supplying the amp in the fudge tin. The Orange is my cab.  I guess I need reverse polarity protection for the amp and maybe the pedals. Can I use an LED for that or do I need another type of diode? I know battery life may be an issue but may be a proper FX power supply mat work better?

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flester

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Re: Centre Negative DC Jack
« Reply #13 on: September 21, 2018, 05:59:13 AM »
Heres what I came up with. The bundle of 6x AA rechargeables to the right of the pedal box has a centre -ve  lead supplying pedals, and a centre +ve  supplying the amp in the fudge tin. The Orange is my cab.  I guess I need reverse polarity protection for the amp and maybe the pedals. Can I use an LED for that or do I need another type of diode? I know battery life may be an issue but may be a proper FX power supply mat work better?

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No problem with the battery life over the last few weeks. Better than rechargeable PP3's.

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phatt

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Re: Centre Negative DC Jack
« Reply #14 on: September 30, 2018, 07:38:34 AM »
Can I use an LED for that or do I need another type of diode? I know battery life may be an issue but may be a proper FX power supply mat work better?

No, you need a diode. 1N4004 or similar.
Yes, a wall wart would be more economical.
Phil.

 

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