Speaker gets extremely hot

[N0TB0T]

When using the serial pin as an output (using not more than an extra transistor and resistor) my speaker gets hot until you can no longer touch it within seconds. I am pretty confident i got the cabling right, triple checked and the circuit works.

Any ideas? I'd love to use it without any other pins on an esp8266, but it seems I'm missing something.

[earlephilhower]

Add a cap between the pin and the speaker to remove the DC component.