2. What are toggle switches used
for?
A toggle switch is a type of
electrical switch that is actuated
by moving a lever back and
forth to open or close an
electrical circuit. There are two
basic types: maintained contact
and momentary toggle switches.
3. What are the types of toggle switches?
The types of switches are classified into four types namely:
SPST (Single Pole Single throw)
SPDT (single pole double throw)
DPST (double pole, single throw)
DPDT (double pole double throw)
TPST (double pole, single throw)
TPDT (double pole double throw)
4. Pole refers to the number of circuits controlled by the switch:
SP switches control only one electrical circuit.
DP switches control two independent circuits (and act like two identical
switches that are mechanically linked). Do not confuse ‘pole’ with
‘terminal’.
The DPST switch, for example, has four terminals, but it is a DP, not a 4P
switch.
Throw refers to the extreme position of the actuator:
ST switches close a circuit at only one position. The other position of the
handle is Off.
DT switches close a circuit in the Up position, as well as the Down position
(On-On).
A DT switch can also have a center position (frequently On-Off-On).
Single pole/throw and double pole/throw switches are by far the most
common switches, but triple and quadruple configurations are also available.
They are commonly denoted 3PST, 3PDT, 4PDT, etc.
5. Configuration
Maintained-contact toggle switches and momentary-contact
toggle switches differ in terms of switch configuration.
Configurations for maintained-contact toggle switches are
described below.
ON/OFF toggle switches have separate ON and OFF functions
and work like light switches.
Three-position toggle switches have a center position that may or
may not perform an OFF function.
6. Configuration
Switch functions for momentary-contact toggle switches include
the following.
Momentary ON describes contacts which interrupt the circuit
when the toggle switch is in the normal, open (NO) position.
Momentary OFF describes contacts which establish a circuit
when the toggle switch is in the normal, closed (NC) position.
Alternate ON/OFF describes a switch where the first actuation
turns the toggle switch ON and the second actuation turns the
toggle switch OFF.
Three-position momentary center-NEUTRAL toggle switches
have a center position that can perform an OFF or NEUTRAL
function.
7. A normally open (NO) toggle switch has contacts that
are open or disconnected in their unactuated (normal)
position.
A normally closed (NC) toggle switch has contacts that
are closed or connected in their unactuated (normal)
position.
8. There are several configurations for pole and throw toggle switches.
Single pole single throw (SPST) toggle switches make or break the
connection of a single conductor in a single branch circuit. This
switch type typically has two terminals and is referred to as a
single-pole switch.
9. Single pole double throw (SPDT) toggle switches make or break
the connection of a single conductor with either of two other single
conductors. These switches usually have three terminals and are
commonly used in pairs. SPDT switches are sometimes called
three-way switches.
10. Double pole single throw (DPST) toggle switches make
or break the connection of two circuit conductors in a
single branch circuit. They usually have four terminals.
11. Double pole double throw (DPDT) toggle switches make or
break the connection of two conductors to two separate circuits.
They usually have six terminals are available in both momentary
and maintained contact versions.
12. Triple pole double throw (TPDT) toggle switches make or
break the connection of three conductors to two separate
circuits. They usually have nine terminals are available in
both momentary and maintained contact versions.
13. What is a DIP Switch, and How Does it Work?
A DIP switch is a dual in-line package switch, meaning that it
consists of a series of switches in a single unit. It is an
electromechanical device requiring a user to manually move the
actuator so that a different electronic circuit is activated or
deactivated. Commonly mounted on a PCB or breadboard, DIP
switches allow users to quickly preconfigure or toggle an electronic
device between a variety of settings or operating modes.
14. Types of DIP Switches
DIP switches come in a variety of types, including
Slide type DIP switches.
Piano type DIP switches.
Rotary type DIP switches.
15. Slide DIP switches are standard toggle switches.
Each switch has two positions - either closed or open (also on/off or 1/0) and therefore
operates as an SPST switch.
There are also three-position slide DIP switches with a central neutral location and a
contact at each end, typically configured as on/off/on.
Any DIP switch can be configured as normally open (NO) or normally closed (NC).
Normally open switches complete the circuit when actuated, while normally closed
switches break the circuit when actuated.
16. Piano DIP switches are similar to slide DIP switches. However,
instead of lying horizontal, with a forward and backward
motion to move the actuator, piano DIP switches are vertical,
requiring an up and down action.
17. Rotary DIP switches toggle position as the user turns in a circular
motion. The amount of rotation determines the output of the
switch.
A rotary DIP switch with four output pins can produce up to 16
different output configurations in binary code.
It can also be configured to operate as an SPDT device and may
have three or four throws for a single pole.
18. DIP Switch Applications
Some of the most common applications for DIP switches are as
follows:
1. Programming garage door openers
2. Programming remote controls
3. Configuration of options on PC expansion cards or
motherboards
4. Adding new items to an IoT network through easy user
configuration
19. What is a Push Button Switch?
A push button switch is a mechanical device used to control an
electrical circuit in which the operator manually presses a button to
actuate an internal switching mechanism. They come in a variety
of shapes, sizes, and configurations, depending on the design
requirements.
20. How Does a Push Button Switch Operate?
Push button switches rely on a simple in-out actuation mechanism.
They can be employed to break (off) or initiate (on) a circuit.
Alternatively, they can provide an input for the user interface of a
piece of equipment or start/stop a particular function.
Push button switches may be categorized as being either momentary
(where the switch function only continues for as long as the
operator is pushing the button) or maintained (where the switch
function stays latched in that status after it has been actuated).
21. Types of Push Button Switches:
Push button switches can be classified as being normally open
(NO) or normally closed (NC).
Normally open (“OFF” position) switches complete the circuit
when actuated, while normally closed (“ON” position) switches
break the circuit when actuated.
22. Push Button Applications and Considerations
Their use is widespread in various applications,
such as vending machines, portable equipment,
household appliances, power tools, and
countless other consumer electronics and
industrial controls.
23. Membrane Switches
What are Membrane Switches?
Membrane switches are a type of human-machine
interface characterized by being constructed from several
layers of plastic films or other flexible materials.
Conductive materials and graphic inks are printed or
laminated onto the surface of these plastic films. They
function by temporarily closing or opening an electric
circuit. The compact and efficient construction of
membrane switches makes them suitable for a vast array
of applications such as household appliances and
industrial equipment interfaces.
24. Membrane Switch Construction
Membrane switches are composed of several components
in the form of layers that are assembled using pressure-
sensitive adhesives or heat sealing films.
Its main parts are an overlay containing the graphic
elements; a circuit that includes the conductive tracks,
metal domes and terminals; and a spacer that maintains a
break between the switch contacts.
25. Overlay: Also known as top or graphic overlay, the overlay is the outermost layer
of the membrane switch. Since this layer is on the exposed side of the membrane
switch, it is made from materials that have good flexibility, clarity, durability,
chemical resistance, and barrier properties.
There are two common materials used for making the overlay,
Polyester: This is a plastic material commonly known as poly ethylene
terephthalate (PET).
Polycarbonate:
Other materials that can be used as overlays are acrylic, vinyl, and PVC.
Graphics can be printed on the reverse side or front side.
26.
27. Domes: Domes are the components that provide tactile feedback. They can be made
from metal or plastic.
Metal Domes: Metal domes are made from stainless steel or copper alloys held in
place by a dome retainer layer or a spacer layer. Aside from providing tactile
feedback, metal domes also function as a part of the circuit. When pressed, the metal
dome shorts the open contacts of the switch.
Plastic or Poly Domes: Plastic domes are typically made from polyester because of
their flexibility; hence "poly" domes.
At the concave side of the dome is a printed conductive ink that completes the
circuit when the button is pressed.
28. Retainer Layer: The retainer layer with the primary function of holding the metal domes
in place. This is commonly made from polyester film, similar to the poly dome layer.
Spacer Layer: This layer is used to create a break in contact between the two
conductors of the switch. This allows the switch to have its open position. In some
designs of tactile-type membrane switches, it can also act as a retainer to keep the
metallic dome in place. The spacer layer has channels between the empty cavities or
the sides of the keypad for venting air. This prevents air from being compressed in the
cavity when the key is pressed.
29. Circuit Layer: This layer is where the conductive paths of the switch are applied.
These conductive paths can be produced through two main methods: screen printing
and photochemical etching.
Screen Printing: This method uses a stencil containing the pattern of the circuit. Silver
conductive ink is flooded on the stencil which is placed above a substrate. The substrate
used is typically a polyester film. This method is used for thinner and more flexible
membrane keypads.
Photochemical Etching: In contrast, this method uses a copper laminated substrate
which is selectively patterned through photolithography and chemical etching. The
result can be a printed circuit board (PCB) or a flexible printed circuit (FPC) that is
thicker and more durable than screen-printed membrane keypads.
30. Benefits of Membrane Switches
Thin and compact profile.
Simple graphic interface construction.
Highly resistant against external elements.
Easy cleaning and maintenance.
31. Applications
The applications of membrane switch include the
following.
•Membrane switches are broadly used in different
applications like industrial, domestic, or commercial.
•These switches are found all over like in cell phones;
calculators, ovens, door lock systems, etc.
•These switches are used to control the 7-segment display.
