How to add 4 LEDs to Arduino Uno Romeo Robot?

I want to add 4 LEDs in a series circuit to 4WD Romeo Uno Mobile Platform Robot.
Do I need another power supply ( 9 volts ) to turn ON and OFF these 4 LEDs?
These 4 LEDs are for looks to dress up the Romeo Robot.

If I need another power supply, could I hook up the Romeo Robot and the 4 LEDs series circuit to a DPDT toggle switch?

Would the DPDT toggle switch do a good job turning both devices or circuits ON and OFF?

Please send reply!


Please send much more detail!

What is a "4WD Romeo Uno Mobile Platform Robot"?

What LEDs do you want to add.

Why do you want to add the LEDs is series rather than parallel?

Why can't you use the robot's existing power supply?

Please post links to any important components. Please read the forum guidelines in the sticky post to find out how to post links. If you can't click on it, you have not posted it correctly.

4 Red LEDs that are 5mm

4 Red LEDs, 1.7 volts, current 20mA, resistor: 110 ohms, 9 volts battery

This is LEDs series circuit information.

Do you think that I could hook up this to Romeo Uno Robot borad and every thing works ok?

Please send reply!


You have done your sums correctly. 110R is correct for the 4 LEDs in series. But this means adding an extra battery to your robot.

You could use the 5V supply from the Arduino. Put 2 LEDs in series with 82R resistor. And 2 more LEDs in series with another 82R resistor. Then you do not need an extra battery and switch.


Thanks for you help!

I will give it a try.