hantto
Member
Hi, i have an 2A water pump and a 1A powersupply. I wanted to limit the current to 1A that is going to the pump beacause it was pumping to fast (and the powersupply is only 1A).
So i calculeted 12/1=12ohms and 12*1=12W. And the nearest one i found in my personal stock was 10ohms 5W. (i will go and buy a 10W one soon)
And when i measured the current with only the resistor and it was 1,05A but when i had both the pump and the resistor the current was 0,61A. With only the pump the current was 1,23A.
So that the pumps resistance should be 12/1,23=9,7ohms, then I measured the resistance of the pump and it was 4,5ohms.
So could someone explain this to me? And how many ohms resistor should i have to get the current to 1A, should it be 12-4,5=7,5ohms or 12-9,7=2,3ohms?
So i calculeted 12/1=12ohms and 12*1=12W. And the nearest one i found in my personal stock was 10ohms 5W. (i will go and buy a 10W one soon)
And when i measured the current with only the resistor and it was 1,05A but when i had both the pump and the resistor the current was 0,61A. With only the pump the current was 1,23A.
So that the pumps resistance should be 12/1,23=9,7ohms, then I measured the resistance of the pump and it was 4,5ohms.
So could someone explain this to me? And how many ohms resistor should i have to get the current to 1A, should it be 12-4,5=7,5ohms or 12-9,7=2,3ohms?