Switches Flashcards
Push to break switch
The current only flows when the switch is not pressed - pressing the switch stops the current.
If it is a push switch the button is often (but not always) black
Push to make switch
The current can flow only when the switch is pressed.
The button part is often (but not always) red
Momentary switches
All of these allow current to flow when pressed but it stops as soon as they are released - they do not ‘stay on’
They can all use the ‘push to make’symbol
Latching switches
All of these stay in one position until deliberately changed. They do not spring back when let go. They can all use this symbol.
Reed switch
These are momentary switches activated by a magnet .
If there is a magnet close by the switch conducts, but if there is no magnet then the switch stops conducting.
They are common switches and are frequently used in alarm circuits where they might be packaged in plastic to protect the glass tube
Micro switch
These switches are different because they are not operated by a persons finger, but usually part of a machine or piece of equipment.
They can have buttons, levers or rollers and are used to detect when a fridge door is closed, a machine has a guard in place, or when part of a machine has reached the end of it’s movement.
Toggle switches
Theses are often (but not always) used as ON/OFF switches and are sometimes marked with these labels
They usually mount through a hole drilled into the material they are used in and fastened with a nut on the front.
They can be SPDT or DPDT (and sometimes other forms as well)
Single Pole Single Throw
Poles are the number of switches inside the main switch. Throws are the number of outputs the switch has.
You can tell the number of these by looking at the number of pins or legs the switch has.
The rocker switch below is a single pole single throw (SPST) since it only has 2 connections.
You can find more information here(right click and ‘open in new tab’ to not lose your progress here)
Single Pole Double Throw
Poles are the number of switches inside the main switch. Throws are the number of outputs the switch has.
You can tell the number of these by looking at the number of pins or legs the switch has.
The slide switch below is a single pole double throw (SPDT) since it has 3 connections.
Double Pole Single Throw
Poles are the number of switches inside the main switch. Throws are the number of outputs the switch has.
You can tell the number of these by looking at the number of pins or legs the switch has.
The illuminated rocker switch below is a double pole single throw (DPST) since it has 4 connections.
Double Pole Double Throw
Poles are the number of switches inside the main switch. Throws are the number of outputs the switch has.
You can tell the number of these by looking at the number of pins or legs the switch has.
The toggle switch below is a double pole double throw (DPST) since it has 6 connections..
These are the most common switches you will see because by using some or all of the connections you can make the switch act like any of the other types.
