1. Selection of rated working voltage of finder relay

The rated working voltage of finder relay is a very important technical parameter of relay. When using a relay, first consider the working voltage of the circuit where the relay coil is located, and the rated working voltage of the relay should be equal to the working voltage of the circuit. The working voltage of general circuit is 0.86 of the rated working voltage of relay. Note that the workpiece voltage of the circuit should not exceed the rated working voltage of the relay, otherwise the finder relay coil is easy to burn out. In addition, some integrated circuits, such as NE555 circuit, can directly drive the relay, while some integrated circuits, such as COMS circuit, need to add a transistor amplification circuit to drive the relay if the output current is small, so it should be considered that the output current of the transistor should be greater than the rated working current of the relay.

2. Selection of contact point load

Contact point load refers to the bearing capacity of the contact point. The contact of finder relay can bear a certain voltage and current during switching. Therefore, when using finder relay, it should be considered that the voltage applied to the contact and the current through the contact should not exceed the contact load capacity of the relay. For example, the contact load of a relay is 28V (DC) × 10A, indicating that the finder relay contact can only work on the circuit with DC voltage of 28V, and the contact current is 10A. If it exceeds 28V or 10a, it will affect the normal use of the finder relay, and even burn out the contact.

3. Selection of coil power supply of finder relay

This refers to whether the finder relay coil uses direct current (DC) or alternating current (AC). Generally, beginners will use electronic circuits in electronic production activities. Electronic circuits are often powered by DC power supply, so finder relays with DC voltage coil must be used.