What is a DPDT relay? A DPDT relay is a relay has two separate switches that operate at the same time, each with one normally open contact or closed through a common entry. We can define the acronym as a DPDT relay two two-position switches.
DPDT refers only to contacts and relay switches, not being relative to its coil impedance, working voltage and current to your contacts.
Up an image that illustrates the most common types of relays, SPST, Relé SPDT, Relé DPST e Relé DPDT. And in the electronic scheme The above and B is input is the output.
SPST relay is the simplest of the relays because it has a simple key, it is widely used in electronic circuits that does not require a two-position switch. The SPST relay is commonly found at the contact of your NO switch (normally Open).
This release is mostly found in version Relay Reed, in other words, a relay having its reed switch, which is a key having a set of contacts inside a glass delivery tube with inert gas, to protect the contacts against atmospheric corrosion. The contacts are closed by a magnetic material or a small coil.
SPDT relay has only one key as the SPST relay but with two positions.
DPST relay is a relay with two switches, but with only one contact, which may be in (normally Open) or NC (Normally closed,pt).