Switch Based on Contact (SPST, SPDT, DPST, DPDT)
by : Antonius (@sw0rdm4n)

Source : https://sw0rdm4n.wordpress.com/2015/05/2...dpst-dpdt/

Understanding switch types is very important when developing an electronic circuit. Below is just several example of switch (not a complete list) classified by pole(s) and throw(s).

[Image: spst.png?w=625]
SPST stands for single pole double throw.  Pole means how many circuit(s) a switch can control. Throw means how many conducting position for a switch. This one is the basic form of a switch, where this switch has only 2 terminals. When the throw is closed means current can flow, meanwhile when the throw is open, current is break.
In order to understand more, let’s take a look here (sorry for bad drawing skills)
[Image: spst_open.jpg?w=625]
For example here we have a gate when the gate is open, means the electrical flow is break.
[Image: spst_closed.jpg?w=625]
When the gate is closed means current can flow and the lamp is on. Since this only has 1 circuit (the lamp in this case), and only 1 throw (only 1 conducting position that will turn the light on, so this switch is called SPST).
Real life example:
[Image: spdt.jpg?w=625]
SPDT stands for single pole double throw. As we can see from the symbol, a single pole double throw switch has 3 terminals.
In order to understand more, let’s take look at below example:
[Image: spdt_open.jpg?w=625]
This one is similar to knife switch model, where the condition is open (current can not flow). The thow can be connected whether on right or left terminal.
[Image: spdt_closed2.jpg?w=625]
[Image: spdt_closed1.jpg?w=625]
Real life example


[Image: dpst.jpg?w=625]
DPST stands for double pole single throw.
In order to understand about double pole single throw, take a look on below example.
[Image: dpst_open1.jpg?w=625]

in dpst , the throw only have one possible conducting, meanwhile it has 2 separate poles.

[Image: dpst_closed.jpg?w=625]

When the condition is closed the current can flow to light both 2 circuits. The while lines are any conducting materials.

[Image: dpdt1.jpg?w=625]

DPDT stands for double pole double throw. This one has 2 poles and 2 throws. This one has 6 terminal(s).
Check out below example:

[Image: dpdtx.jpg?w=625]
Real life example:

I hope this guide can be a light for those who wanted to understand more about switching in order to do the “Art of controlling the electron”.

Users browsing this thread: 1 Guest(s)