Relays are commonly used in electronics. They are simply switches that can be turned on and off by electricity. The relay consists of an electromagnet that moves a lever (the armature) which makes the actual electrical connection between contacts. Relays offer the benefits of

• Safety isolation. By using a magnetic field to control the switch contacts, there is no physical connection between the control inputs and the electricity being switched
• High current capability. A relay that can switch a large 100 Amp circuit may be controlled by a small 50 milliamp (0.05A) signal
• Reliability. There are relays that have been in service for over 100 years

Relays are typically referred to by their current capacity in Amps, the voltage capacity in Volts, and the contact type. The most common types are

• SPDT is Single Pole Double Throw. This means that a single circuit can be switched between two positions
• Double Throw. This means that two circuits, or Poles, can be switched between two separate positions at the same time

There are other relay forms but these are the most popular

In addition to their common appearance in industrial control panels, relays can also be controlled by networks or serial signals.

Our RLY-232 control board has two SPDT relays that are controlled by RS232 serial signals making it possible to control circuits directly from your computer. You can now turn on and turn off equipment directly from your PC with software control. We provide example software and documentation to make interfacing with your system straightforward