# Power supply for a Microcontroller/microprocessor in a boat

#### vegovs

Joined Jun 13, 2018
3
I am making a project which includes a Raspberry Pi or an Arduino that needs power from the existing circuitry on different boats. The voltage may differ from 10-30V and i need to make a Power Supply that lowers it and keeps it regulated to 5V. I do not remember anything from my electronics class and need help!

The question is, how can i get 5V DC from circuitry that may have 10 to 30 V?

#### dl324

Joined Mar 30, 2015
14,706
Welcome to AAC!

Use a voltage regulator. Plain old 7805 linear regulator, LDO, buck; your pick. Just make sure you consider maximum input voltage and power dissipation.

#### vegovs

Joined Jun 13, 2018
3
Welcome to AAC!

Use a voltage regulator. Plain old 7805 linear regulator, LDO, buck; your pick. Just make sure you consider maximum input voltage and power dissipation.
Thank you Dennis, could you give me an example when i should consider max-voltage and power dissipation?

#### vegovs

Joined Jun 13, 2018
3
hi vegovs,
Welcome to AAC.
Look thru this link for options.
E
Thank you! I am guessing these are variable and somewhat more expensive than a static voltage regulator?

#### dl324

Joined Mar 30, 2015
14,706
Thank you Dennis, could you give me an example when i should consider max-voltage and power dissipation?
With a linear regulator, power dissipation can be an issue.

If you have 30V in, 5V out and a current of 1A, the regulator would dissipate
$$\small P = I*V = 1A * (30-5V) = 25W$$
Without a good heat sink, a 7805 would go into thermal protection and not be very useful.