An optoisolator receives a low-voltage signal on the LED side and produces what on the output side?

An optoisolator, also known as an optocoupler, is designed to transfer an electrical signal using light waves to maintain electrical isolation between its input and output. When a low-voltage signal is applied to the LED side of the optoisolator, it activates the LED, which emits light. This light is detected by a photodetector (such as a phototransistor) on the output side.

In many applications, the output side of the optoisolator can be connected to a higher voltage supply than the input. As a result, when the LED is on, the photodetector triggers, allowing current to flow through it, which can lead to a higher output voltage compared to the input voltage. This ability to produce a higher output voltage while isolating the two sides electrically is crucial in many circuit designs, making the optoisolator a versatile component in interfacing between different voltage levels safely.

The other choices do not accurately represent the typical use case for an optoisolator. The device does not simply lower the voltage, vary the voltage, or produce a constant voltage; instead, it specifically allows for a higher voltage output driven by the triggered response from the input signal.