Relays

A relay is essentially an electrically operated switch. It uses a small amount of electrical current to control a much larger current flow in a separate circuit. Imagine a single pole double throw relay or a SPDT as a fancy light switch. The small current from your control signal (like a button press) acts like a finger flicking the switch. This, in turn, connects or disconnects the higher current flowing through a separate circuit, turning your light on or off.

In linear actuator control, a single pole double throw relay might be used to control the direction of the actuator. By flipping the switch (changing the polarity) with the relay, you can determine whether the actuator extends or retracts. There are other relay configurations with multiple poles and throws that offer even more complex control possibilities.

A relay functions like an electrically operated switch, controlling a high-power circuit with a low-power signal. Here's a breakdown of how it works:

1. The Coil: Imagine a coil of wire within the relay. This coil acts like an electromagnet.
2. The Control Circuit: This is the low-power circuit that sends a signal to the relay. It could be a switch you press, a signal from an Arduino, or any other source of low voltage.
3. The Contacts: Inside the relay, you'll find sets of metal contacts. These act like the actual switch mechanism. There are different relay configurations with varying numbers of poles (contacts that connect/disconnect) and throws (number of positions each pole can switch to). A common type is the Single Pole Double Throw (SPDT) relay, with one control pole and two output contacts.

In essence, the small current from your control circuit acts like a trigger, flipping the switch (contacts) in the high-power circuit based on the relay's configuration (SPDT, DPDT, etc.). This allows you to control powerful devices like linear actuators with a simple low-voltage signal.