• 1 × ATmega328P
• 1 × 28pin IC socket
• 1 × LM317T
• Resistors
  • 1 × 470Ω
  • 1 × 680Ω
  • 1 × 3.3kΩ
  • 1 × 47kΩ
• Capacitors
  • 1 × 10µF Electrolytic
  • 1 × 100µF Electrolytic
  • n × 0.1µF (104) Ceramic
• 3 × Rectifying Diode 1N4001

The voltage regulator circuit is based on the LM317, mainly because this is what I currently had handy, that would give me a comfortable margin of error. There can be up to a 40V difference between input and output voltage, which means this circuit should be able to handle a input voltage of up to 43V between GND and V_BAT

The values of R1 and R2 where chosen from resistors I had available, using this LM317 Voltage Calculator. I was aiming for something around 3.3V.

R1=470Ω R2=680Ω, which gives a output voltage of about 3.06V, which is acceptable for all of the components.

• RFM69HW 1.8V–3.6V.
• ATmega328P 1.8V–5.5V.
• DS18B20 3V–5.5V.

V_BATS

• http://www.muzique.com/schem/lm317.htm
• http://www.csgnetwork.com/antennagenericfreqlencalc.html
• http://www.st.com/web/en/resource/technical/document/datasheet/CD00000455.pdf