I made a circuit with some components (arduino, wifi board, ultrasonic sensor, sound sensor, light sensor, temperature sensor, humidity sensor, some leds and other components) on a breadboard.

The whole circuit is 5V. The whole circuit drains about 100mA during normal operations and up to 350mA during wifi communication.

Now I'm designing the final PCB.

My question is, which is better?

1) 5V 1A power supply (like smartphones charger)

2) 9V 1A power supply and a voltage regulator on pcb to get 5V (i was thinkg LM317T)

EDIT: i'm asking this question because with my 5V 1A power supply i actually measure about 4.4V when the circuit is ON (probably due to voltage drops in the breadboard) and I don't know if this could damage the circuit (arduino and wifi board). I think that with a voltage regulator i will have a clean 5V, but this requires me to buy a 9V adapter and add the LM317, that could add some heat to the circuit.

I don't care much about cost, size and power loss, but i really need reliability

  • \$\begingroup\$ Better = cheaper, smaller, more efficient, lower voltage noise/spikes? \$\endgroup\$
    – Andy aka
    Commented Feb 24, 2015 at 17:44
  • \$\begingroup\$ @Andyaka Yes ... ;) \$\endgroup\$
    – brhans
    Commented Feb 24, 2015 at 17:52
  • \$\begingroup\$ Cheaper doesn't always mean smaller. lower noise doesn't always mean more efficient. Please define what "better" means and list the most important parameter of betterness. \$\endgroup\$
    – Andy aka
    Commented Feb 24, 2015 at 17:57
  • \$\begingroup\$ you're right, question edited :) \$\endgroup\$ Commented Feb 24, 2015 at 18:06

1 Answer 1


There are trade-offs, as always. Having a regulator on the board board gives you some flexibility in choosing the power source for the circuit, clean regulated voltage, which are good. But it is an additional cost, size, power loss and heating, which are bad.

  • \$\begingroup\$ Cost, size and power loss aren't problem for me, and I hope that heat will not be a problem :D \$\endgroup\$ Commented Feb 24, 2015 at 17:57
  • \$\begingroup\$ Maybe a better question is... Normally do you use a main voltage regulator in your circuits or adapaters are stabilized enough for this kind of circuit? \$\endgroup\$ Commented Feb 24, 2015 at 18:00
  • \$\begingroup\$ I prefer placing regulators (switching ones to maximize the efficiency) on every board, especially in systems which have components somewhat spread in space. \$\endgroup\$
    – Eugene Sh.
    Commented Feb 24, 2015 at 18:02

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