Arduino Uno Issue: No output power I am currently a first time Arduino user. I decided to get one and start prototyping basic types of circuits.

I have built various basic circuits with the Arduino Uno prototype board and it worked completely fine. I am using the Arduino board to source power to my circuit (5V). However, after building the following circuit, everything stopped working:







simulate this circuit &ndash; Schematic created using CircuitLab

I don't get output from any of the Arduino pins and I cannot upload programs to the board. The yellow LED still blinks, and the green power LED remains green and active.

I cannot figure out how I managed to burn the board. The current is around 22.72mA, which is pretty far of the 40mA absolute rating.
The schematic you have drawn is completely safe to connect to an Arduino PWM pin. It may not be an optimal choice (closing multiple switches will change the brightness of segments), but it's not dangerous. As you said yourself, the current is limited to a safe value even if there's a dead short in the 7-segment display.

Typically, you burn your board when you connect/disconnect stuff while your Arduino is powered (because intermediate circuits may be unsafe even if the final result is OK), or when you built a circuit which is different from what you think you have built.