Problem with voltage division

So I have Arduino Pro Mini 5v and Dc adaptor 12v. What I want to do is conect arduino to it but 12v 1a is to much for raw pin (already burned built in ldo) I also tried to divide it with resistors, it looks kind of fine when it’s not conected with 2 diodes and resistors I managed to get 6v but when i conect to my project voltage drops to 3v and non of the sensor work
My question is what can I do to make it work? :slight_smile:
Maybe capacitors would help?
I also have ldo from arduino uno but i think i fried it (wrong conection)
Any suggestions?
Thank you for your answer! :slight_smile:

Get a 7808 8V regulator and step the incoming 12V down using that, provide 8V to Vin pin. Don’t forget the
capacitors for the regulator - google “7808 datasheet”.

If you’re not doing any sensitive analog stuff a DC-DC converter direct down to 5V would be more effcicient.

Voltage dividers are not for power. They should be unloaded and for measuring only.

I also tried to divide it with resistors, it looks kind of fine when it's not conected with 2 diodes and resistors I managed to get 6v but when i conect to my project voltage drops to 3v

When you try to "power" something with a voltage divider, there are two problems -

The load becomes part of the circuit. The resistance of the load is in parallel with the "bottom" resistor, creating a 2nd path for the current, lowering the total resistance for the bottom-half of the voltage divider. That lower resistance means less voltage is dropped across the bottom, and more voltage across the top.

And, most "real world" loads don't have constant resistance... If you're running your Arduino and you turn-on an LED, more current flow (meaning the effective resistance is lower) and the voltage will drop. There are other things that can change the current, but the LED should be easy to understand.

We don't normally measure the resistance of an "active load" because it varies, but it does have a resistance. We're usually just interested in the maximum current load.