How to convet 12vdc 7ah to 5vdc 2A and 12vdc 7ah to 12vdc 1A

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mdsalmannn

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hii i want to convert
1. 12v 7Ah battery supply to 5v 2A for my robot and i want to convert
2. 12v 7Ah dc to 12v 1A for motors section

could you please suggest me any circuits which can make my dream possible thankful for the helper.
 

for 12v to 5v you can use a switching regulator like LM2596 https://www.ti.com/product/lm2596 , you can get a ready board from ebay for about $1 if you want a ready solution

For 12v to 12v I don't understand what you mean, you have 12v input and 12v output, why do you want to use a circuit, is a current limit to 1A necessary?
 


i had 12v input with 7Ah and i need only output of 12v with 1A i want to limit the current so how can i achieve it
 

If you limit the current to a motor then it might not start running because it uses a high surge of current to get started. if the load requires more power than 12V at 1A then current-limiting will cause the motor to slow down or stop.

Your little 7Ah battery can provide 0.35A for 20 hours or 3A for about 1 hour. It might provide 1A for about 5 hours.
 

There is no need to limit the current, this is just a waste of energy and reduces the efficiency , the load will get as much as it needs.
As I read in another forum if Johny wants to eat one apple he is going to eat one no matter if there are four, five or eleven apples on the table.
It's the same with the current, the load resistance/impedance is what adjusts the consumed current, the battery doesn't force the current.

Do you have any special case for which you want to limit the max current?
 


yes, as i think ARM7 is not able to connected with 7A battery, connecting it with this battery will create problems in the total circuit operation as well as with ARM7 also, as these devices works on low currents.
 


mdsalmannn said:
i understand what you are saying but consider when u keep an small led to a 12v 7A battery and say what ever apples it has to eat it will take only the required one it will not work in this case the light will blow off.
Click to expand...

But a LED is not a motor. They are extremely different things. You can safely connect a motor to a 10AH or 100000000AH battery. I would suppose your motor starts/stops, and perhaps reverses. Any circuit designed to limit current must also handle those conditions else the motor would be starved for power. Simple current limiters use the voltage drop across a resistor to measure current - not a good idea in your case as the battery voltage is the same as the motor. You might consider a fuse instead; say a 2 or 3A SLO-BLO fuse.
 

A low power led (the normal ones intended for 20-30mA) will blow anyway if you don't use a current limiting resistor, even a 0.1A supply will be able to damage it.

The only way to connect a led directly to power supply without the resistor is when a constant current driver is used or a very weak source with high internal resistance like some LRxx batteries (the small button size ones)
 

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