7vdc buck regulator for Arduino Mega PSU

Job ID: 32729176

Budget: $30 – $250 USD

We need a 24vdc in to 7vdc out - buck converter @ approximately 1.5amp to power an Arduino Mega / DUE.
The onboard regulator gets hot if driven above 8vdc, so I want to have a dedicated 7vdc PSU that doesn't get hot like a traditional linear LM7812 does.

I've used AL8805's in the past and even LM2596's, so am open to ideas as long as they're not end of life components which will be hard to source later.

Just need a schematic and formulas for 24vdc in - 7vdc out.
Milestones will be paid:
1. 50% on supply of the circuit details
2. 50% on completion of testing the circuit (will need 3 days to get parts and build it)