I've had a small electronics project to add autofire to my 3D-printed joystick. I am using a 555 timer for this, whose supply voltage range is 4.5V-16V. Knowing that the C64 outputs 5V on its joystick ports I figured I could drive the 555 with that.
However, I just measured the Keyrah db9 output voltage, and it's only 3.5V? Is this normal, i.e. do I need to add a step-ups regulator to my circuit to go from 3.5V to 5V?