Arduino Power Supply v18.08

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Design

Requirements

  • Up to 300 mA supply (200 mA would likely be enough)
  • 7-12 V DC output
  • 120 V ac input
  • Stable voltage reference of less than 5V (not needed if Arduino's internal reference is accurate enough, TBD)

Research

Non-isolated design could waste more power if Arduino is drawing less than the designed maximum output current. Isolated could lose a small amount of efficiency to transformer but would waste less power when the Arduino is drawing less than the designed maximum output current. For this application, isolated seems to be the way to go.

Power requirements for Arduino Mega (usually <70 mA, 200 mA max) and RepRap Discount Smart Controller (40-100 mA?). 300 mA max to power control and display circuits.

Drawing Power from Grid without Transformer for *Low Power* Applications

Precise voltage measurement with the Arduino

High Efficiency 400W AC/DC Power Supply Reference Design

Calculations

QUCS-S Simulation

Simulation providing 9V at >250mA

Electronics Design

These designs are not guaranteed to be safe or functional. Use at your own risk.

[1]

Prototyping

Successfully converted 120Vac to 10V at 380mA

Bill of Materials

Isolated

Fuse: FUSE GLASS 500MA 250VAC 5X20MM

Transformer: XFRMR LAMINATED 6VA THRU HOLE

Bridge rectifier: RECT BRIDGE 2A 40V 4SMDIP

Filter capacitor: CAP ALUM 680UF 10% 10V RADIAL

Output zener: DIODE ZENER 12V 5W AXIAL

Total cost of components ~$10

Non-isolated

Fuse: FUSE GLASS 500MA 250VAC 5X20MM

Cac: CAP FILM 10UF 5% 400VDC RADIAL

Cac discharge resistor: UPL1.064 RES SMD 1M OHM 1% 1/4W 1206

Bridge rectifier: RECT BRIDGE 2A 40V 4SMDIP or 4xUPL4.004 DIODE SCHOTTKY 40V 1A SOD123

Filter capacitor: CAP ALUM 680UF 10% 10V RADIAL

Output zener: DIODE ZENER 12V 5W AXIAL

Total cost of components ~$7