AC power control by solid state relay

We may want to control the AC power supply with a microcomputer. Traditionally, transistors and electromagnet relays have been used for such applications. In recent years, these relays are being replaced by semiconductor devices. The solid-state relay of this semiconductor element has the advantages of long life because it has no moving parts and low power consumption.

In this time, I introduce two types of solid state relays. The first one is a high power type. Since the power supply side and the control side are separated by a photo coupler, it can be used with confidence. There are two control terminals, and the power is turned on with a potential difference of 3 to 5 V with respect to ground.

The other one has three control terminals. The solid state relay is controlled by the transistor. The control side has 3 terminals, and there are a ground, a power supply, and a control terminal. There is an LED on the board, and you can see if there is a voltage at the control terminal.