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Author Topic: DC output tweak  (Read 1070 times)

Lex

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DC output tweak
« on: April 10, 2020, 05:00:51 AM »
Hello,

I have to test a device but Im without the right adaptor.
Have many adaptors from previous devices so I want to use one.

So I have one idea:
- I have to lower DC output from an adaptor that is 19V 2.5A to 18V 1.5A.

I suppose that I could do it adding one (or more) diode/resistors and placing it on the cable. I have to cut the cable and turn the polarity anyway.

Since I need to drop (only) 1V, I suppose i could use something  like a 5A diode and simply place it in series?
But now Im not sure about dropping current from 2.5A to 1.5A

I'm thinking in the right direction and this is possible to do,
or im just dreaming?

Cheers

Lex

Enzo

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Re: DC output tweak
« Reply #1 on: April 10, 2020, 09:34:29 AM »
Current is drawn by the load, current is not pushed out of the power supply.   Think about the wall socket in your home  It may have a 15 amp breaker in the service panel, but only the current needed flows.  meaning a 100 watt bulb won't be brighter in a 30A circuit than a 20A circuit.   Your adaptor only needs to have the current you need as a minimum.

mmeanwhile what are we powering that would be sensitive to only one volt difference?  Usually the adaptor voltage is a rough thing, and the device will have internal voltage regulators to make the 5v and 15v or whatever that it needs.

joecool85

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Re: DC output tweak
« Reply #2 on: April 10, 2020, 10:02:33 AM »
I'm with Enzo, just reverse polarity so it matches what you need and you should be able to simply plug it in.  What is the device you are trying to power?
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Lex

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Re: DC output tweak
« Reply #3 on: April 11, 2020, 05:21:44 AM »
Hello, thanx for answers.

It's Hotone Nano amp, and the other adaptor is from an old Del notebook.

Quote
Current is drawn by the load, current is not pushed out of the power supply.   Think about the wall socket in your home  It may have a 15 amp breaker in the service panel, but only the current needed flows.  meaning a 100 watt bulb won't be brighter in a 30A circuit than a 20A circuit.   Your adaptor only needs to have the current you need as a minimum.

Well, now Im think about that , it seems logical.

But would so small class-d board be overload protected  .. ?

If it was old some skool analog thing well I could find the fuse and change it ..

CHeers

Lex
« Last Edit: April 11, 2020, 05:28:03 AM by Lex »

joecool85

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Re: DC output tweak
« Reply #4 on: April 11, 2020, 09:44:16 PM »
Hello, thanx for answers.

It's Hotone Nano amp, and the other adaptor is from an old Del notebook.

Quote
Current is drawn by the load, current is not pushed out of the power supply.   Think about the wall socket in your home  It may have a 15 amp breaker in the service panel, but only the current needed flows.  meaning a 100 watt bulb won't be brighter in a 30A circuit than a 20A circuit.   Your adaptor only needs to have the current you need as a minimum.

Well, now Im think about that , it seems logical.

But would so small class-d board be overload protected  .. ?

If it was old some skool analog thing well I could find the fuse and change it ..

CHeers

Lex

Correct the polarity and run with it. The circuit will never know the difference.
Life is what you make it.
Still rockin' the Dean Markley K-20X
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Lex

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Re: DC output tweak
« Reply #5 on: April 12, 2020, 06:58:12 AM »
Thanx all,

did it, nothing fried or melted .. amp works.

BTW:
Always wanted to know but never asked, some cables / adaptors have at the end a plastic cylinder - is this just a joint to change polarity, kind of a mini fuse or just a usability insert to help cable unplug .. or sth else ?

Cheers

Lex

joecool85

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Re: DC output tweak
« Reply #6 on: April 15, 2020, 09:59:06 AM »
Thanx all,

did it, nothing fried or melted .. amp works.

BTW:
Always wanted to know but never asked, some cables / adaptors have at the end a plastic cylinder - is this just a joint to change polarity, kind of a mini fuse or just a usability insert to help cable unplug .. or sth else ?

Cheers

Lex

This is a ferrite bead also known as a ferrite choke.  It removes high frequency noise from the power supply before it hits the amp.
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Lex

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Re: DC output tweak
« Reply #7 on: April 16, 2020, 03:31:06 AM »

This is a ferrite bead also known as a ferrite choke.  It removes high frequency noise from the power supply before it hits the amp.

Thanx for reply, learned sth again !