From (12v 2.5A DC) to (12v 1.0A DC)

Adam Binder Rogacki said:

I have a DC motor that only can handle 12v 1A but my power supply is 12v 2.5A, so I wanna reduce the current to 1A so I can run my motor.

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That's why we kept asking the question, as we suspected you had a non-problem.
Many devices such as motors and appliances only take the current they need.
For example, you can turn on your car heater fan that takes a few amps and it's connected to a battery that can supply several hundred amps without any problems
It will only draw its rated current and so will your motor, even if connected to a supply that can deliver 100A.

likely over your capabilities but not your EE aware friend's https://www.microsemi.com/document-...iting-techniques-for-switching-power-supplies
also does not your device have integrated pwm load/speed control as many portable tools do . . .
. . . an alternative easy solution that requires experimental pick of suitable components is incandescent bulb OR multiple matrix (← may have unsuitable reaction delay) OR a std. series over current limit https://en.tdk.eu/tdk-en/545938/pro...c-thermistors-for-overcurrent-protection?t=ps (← !! likely !! reacts faster) , https://www.resistorguide.com/ptc-thermistor/ by https://www.google.com/search?q=overcurrent+protection+nonlinear+resistor

ci139 said:

it is not the current been reduced - but the output voltage - ever faster satrting from certain current - specified as the current rating of the supply
unless the load is (a sophisticated circuit) drawing as much as possible from input until the input voltage drops below certain margin

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With all due respect, and no insult intended, is English your first language? Second? Third?
Again, no disrespect -- it would just explain why I can never understand any of your posts.

hyedenny said:

With all due respect, and no insult intended, is English your first language? Second? Third?
Again, no disrespect -- it would just explain why I can never understand any of your posts.

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I think it's just the language that geniuses speak...

KeepItSimpleStupid said:

USB is crazy anyway. So, I bought a 2.1 A charger with a 12 V lighter and 120 V input with two ports.
One will charge my cell and the other won't. The cell charges at 500 mA. My GPS charges at 1.5 A. I can charge both items together if I plug them in a certain way. No mention of anything to that effect on the box.

I have one of those USB voltage/current inline meters to check.

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It may be the way the D+ and D- pins are wired. I think there are about 3 different ways