Im trying to work out what resistor should I use for a school project but I keep getting confused I need to drop a 6V input to a max of 5.25V output but a min 4.25V, can anyone help me out with this?
Kind regards

-Vincent

 

Apply your Ohm's Law.

 

Two diodes in series will drop it to 4.6V

What are you powering?

Mike.

 

you must now how much current that is flowing i.e 6volts minus 1 volts and say .1 A is abt 10 ohms..but maybe you need some low voltage regulator or a simple "voltage divider"..excuse my english ..i'm from sweden...Holger

 

Im trying to power a USB device, but the thing i need to produce the current is 6V and a usb doesnt go any higher than 5.25V

 

If you don't know what current the device will draw then a resistor is no use. The simplest method is to connect two diodes in series with the positive supply - 1N4001 will handle 1A and USB can only supply up to 500mA.

Mike.

 

Where are you getting the power supply from?

Use a low droput regulator.

Be warned, if it's four AA cells, the voltage will quickly drop to below 5V which where even most low droput regulators stop working.

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hello,

Voltage dividers are good as long as the current drawn by the load is low (10 x less ) compared to the current flowing in the resistors network.
now if you do not have a fixed load or if the load takes up too much current your best bet is either a low drop out voltage or diodes in series....

best of luck
Antonio