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

[crutschow]

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.

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.

 

[ci139]

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

 

[hyedenny]

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

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.

 

[throbscottle]

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.

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

 

[throbscottle]

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.

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