Potential Overload When Connecting Multiple Components to Arduino Uno?

Other Hardware General Electronics
1

Hello everyone,

I'm a beginner working on an Arduino project and could use some advice.

I'm planning to connect several components to a single Arduino Uno board, but I've heard that this might cause an overload or other errors. Here is the list of components I want to use:

  • 1-Channel 5V Relay Module
  • 5V Cooling Fan
  • 16x2 I2C LCD Display
  • Optical Fingerprint Sensor
  • Piezo Speaker
  • 3x LEDs (one Red, one Green, one Blue)

My main questions are:

  1. Will I actually run into problems if I power all of these components directly from the Arduino Uno's 5V pin? If so, I'd like to understand the technical reasons why.
  2. If this is a problem, which components should I power using a separate, external power supply?
  3. I would also appreciate any advice on how to properly wire the circuit with an external power supply for stability. For example, is it correct to assume that the relay and the cooling fan are the primary candidates for external power?

Any help or guidance would be greatly appreciated!

Thank you in advance. :blush:

2

How are you planning to power your setup?

The technical reason is that components draw current. If you power from USB you have 500 mA available. If you power with e.g. 9V in Vin or barrel, the 9V is converted to 5V and the surplus power (delta V * I) is converted to heat; the converter has virtually no heat sink and can easily overheat and shutdown.

Relay and fan. Is the fan controlled by the relay? A schematic how you visualise everything might be useful to get better advice.

3

Gil's Crispy Critter Rules for Processor Hardware:

  1. Rule #1: An Arduino is NOT a Power Supply!

  2. Rule #2: Never connect anything inductive (motors, speakers) directly to an Arduino!

  3. Rule #3: Avoid connecting or disconnecting wires while the power is on.

  4. Rule #4: Do not apply power to any pin unless you are certain of what you're doing.

  5. Rule #5: Do not exceed the maximum voltage or current ratings.

  6. Rule #6: Many Arduinos cannot power transmitters directly.

  7. Rule #7: Before powering your project, take a break and double-check the wiring.

  8. Rule #8: Bad soldering makes for project failure.

LaryD’s Corollaries:

  1. Coro #1: When starting out, add a 220Ω resistor in series with both input and output pins to protect against shorts.

  2. Coro #2: Invest in a Digital Multi-Meter (DMM) to measure voltages, currents, and resistance.

Note: Violating these rules can turn your Arduinos into crispy critters. For optimal performance, keep your wires under 25 cm (10 inches).

Additional Tips:

  • The L293 motor driver, though common, is inefficient as it can lose around 3V as heat when driving both legs of a motor. Consider using a motor driver with MOSFET outputs to reduce heat loss and conserve battery power.

  • The nRF24 radios do not work very well when powered with an Arduino even if the 5V adapter is used.

  • For more on powering Arduino boards, explore this guide: Powering Alternatives for Arduino Boards.

4

Can you please explain what your project is.

What do you need the relay module for.
Maybe you can replace it with a mosfet module, which doesn't need any power.
Leo..

5

A linear regulator which the Arduino uses works like an automatic variable resistor in series with the load:

  • It takes a higher, varying input voltage and outputs a lower, steady voltage.

  • Inside, a pass transistor (usually a BJT or MOSFET) drops the extra voltage.

  • A reference (like a band-gap diode) and an error amplifier compare the output to the desired set voltage.

  • The amplifier adjusts the pass transistor so the output stays constant, even if input voltage or load current changes.

    Downside: the extra voltage is burned off as heat, so efficiency = Vout / Vin.

Note: These regulators can get hot enough to melt there solder connections.

6

Still need help?

7

I've been busy lately, so I haven't been able to check it out, but I'll read your posts. Thank you for your interest.

8

thank you very much

9

thank you

10

My guess: this will fail... may work for some time though...
Especially the fan and relay can easily take more current than Arduino can deliver...
And even more if you feed the arduino from the barrel plug with 9V or more.