What is a Time Switch : Working, Installation & Its Applications

Nowadays, energy conservation is very essential because day by day the rates of electricity bills as well as power cuts are increasing. Consumers are looking for different methods to reduce the usage of electricity, so this can be attained with a time switch by limiting consumption within the power supply. Time switches are also known as a timer or timer contactor that is used to control an electric switch. This is an electronic device, used to control the On & OFF time of equipment. This switch can be arranged in an existing power circuit that is connected to the mains power including a contactor or a relay. After that, these switches can be plugged into a wall. This article discusses an overview of a time switch – working with applications.

What is a Time Switch?

A time switch definition is, a device that has an inbuilt electronic or mechanical timer to control an electrical circuit by turning ON & OFF at a preset time is known as a time switch. These switches generally used in different areas like residential & commercial buildings, gardens, schools, fountains, water pumps or irrigation, offices, lighting indoor or outdoor, ventilation systems & other types of devices that need to be controlled throughout the day. These switches can be programmed every day, weekly, and every year.

The time switch symbol is shown below.

Time Switch Symbol
Time Switch Symbol

How Does a Time Switch Work?

A time switch simply plugs into a socket in between the power plug & the actual socket. So this arrangement simply allows any device to get power at a particular time. Generally, a time switch is available with a cover that includes some information on how to utilize this switch & its rating limits. This switch includes a dial that is used to set it to the correct time.

So the dial on this switch maintains time similar to a watch or a clock. When the dial on the switch moves forward, it activates the devices at fixed times by turning them ON and OFF. Throughout the day, some units permit the consumer to set the switch many times.

Generally, time switches are available in two versions electronic and mechanical. An electronic time switch is programmed to turn ON and OFF at fixed times whereas a mechanical time switch frequently allows a restricted number of time settings, although electronic time switches normally allow the number of times that a mechanism is switched ON & OFF every day.


Why do you need a Time Switch ?

A timer switch can save money on energy costs, improves home comfort and makes life more convenient. A timer switch is an easy way to automate the lights, water heater and other appliances so that they operate at times when electricity rates are lower. Some timers even have built-in weather sensors that adjust the switching times according to the outside temperatures.

Types of Time Switches

There are three types of time switches which are discussed below.

Analog Time Switch

The analog time switch is also called the mechanical or manual switch. This switch is mainly designed based on a spring to track the time. These switches are extremely simple to utilize to wind the dial to a precise time. Actually, it is related to setting your watch or utilizing a time knob on your oven.

Analog Timer Switch
Analog Timer Switch

In addition, because of their simplicity, these switches are fairly strong so it is very stronger to break any mechanical device as compared to a digital one. These types of time switches are fairly cheap. Based on time settings, these switches may vary based on the model. Some analog time switches allow you to set the time period to 24 hours and some switches set to one hour time period.

The benefits of using an analog time switch mainly include reliability, inexpensive, simple to use, durability, and installation is easy.

Digital Time Switch

A time switch that is programmable is known as a digital time switch. As compared to analog time switches, these types of switches give many options to handle many different situations. These switches provide numerous on/off cycles within 24 hours period. In addition, the on-off time can be set above just one. Similar to mechanical types, these switches are available in two types plug-in & in-wall.

Digital Type
Digital Type

Some digital time switches are available with passwords so you or any stranger cannot be changed time settings. There are some digital time switches available with different sensors. These switches are used to identify sunshine or movements within their surrounding region & control the lights accordingly.
Modern digital time switches use smart technology so one can connect these switches to tablets, and phones to use as a remote control device. Some models support different services like Google Home and Alexa which allows for voice control.

The digital time switches advantages mainly include; these switches are versatile, provide various options including sensors, etc.

Astronomic Time Switch

The astronomic switch is one type of digital switch but they utilize a different system as compared to ordinary digital time switches. The working of these switches mainly depends on the time of the day. These time switches are available with inbuilt technology which helps in calculating the correct sunrise & sunset timings. Consequently, they control the lights based on calculations by turning them ON and OFF. In addition, there are different models also available including remote control but they don’t provide various other options.

Astronomic Time Switch
Astronomic Time Switch

The astronomical timer switch controls loads automatically according to a fixed weekly plan. So the feature of astronomic gives sunset ON & sunrise OFF settings to avoid the requirement of separate photo control devices.

The applications of astronomic time switch mainly include street light control, HVAC, pumps, fans, livestock feeders, poultry equipment, and heating or ventilation equipment.

Time Switch Wiring Diagram

The circuit diagram of the small timer light switch is shown below. This is a simple transistor-based electronic timer circuit, used to drive high frequency-based white LED for a fixed time out. This circuit operates with a 12V dc supply and this circuit is very helpful for in-car reading. Once the circuit is designed then connect the unit to an appropriate location in your car & activate the circuit from the in-dash standard cigar lighter socket. So, the timer-based light switch is very simple to design, use and less costly, and easy to understand.

Circuit Diagram of Time Switch
                Circuit Diagram of Time Switch

The required components to build this timer-based light switch mainly include a Switch-S1, 12V DC, 1N4001 D1 & D2 white LED, potentiometer P1-100K, Resistors R1-210E, R2-10K, R3-12K & R4-270E, capacitor C1 – 470uF, transistors T1- BC547 and T2- BC337-40.

Circuit Working

The circuit is connected as per the above-shown diagram using the required components. The working of this timer switch follows as; The ‘T1’ transistor is deactivated through potentiometer P1 & resistor R2. Once the ‘S1’ trigger switch is pushed, then the ‘T1’ transistor’s base terminal is simply connected to the +12V supply through the R2 resistor. So, this  ‘T1 transistor activates the D2 white color LED. Here, the flow of current toward the D2 while LED is controlled by the ‘R4’ resistor.

Once the ‘S1’switch is pushed, then-current supplies into the ‘C1’ capacitor throughout the ‘R1’ resistor & charges it. As a result, once the ‘S1’ switch is opened the flow of charge within the ‘C1’capacitor keeps the ‘T1’transistor turned on until all the charges discharges away throughout the potentiometer P1 & R2 resistor. Here, the main function of the potentiometer is to change the performance of the timer switch by simply increasing or decreasing the resistance of the P1 potentiometer on time by the user. If the potentiometer is set to a minimum, the circuit on time must be zero seconds. So, if the potentiometer is set to maximum, the timer circuit on time must be maximum as per the timer switch specification.

 How to Install a Time Switch ?

When a timer switch is properly installed, it can help reduce energy costs. If there is an existing timer, It can be installed easily just by replacing it. Else some basic hand tools and a screwdriver is required. To begin, turn off the power to the circuit at the breaker box and test the switch with a voltage tester.

1. Use a wire stripper to remove about 1/2 inch of insulation from each end of the wires leading to the switch and on either side of the switch itself.

2. Connect one lead from the new timer to each wire by twisting them together with pliers or another tool for stripping and twisting wire ends together (do not use electrician’s tape).

3. Connect the other leads from your new timer in exactly the same way as before (using wires from either side of the box), then connect them both back into their respective places in the electrical box using wire nuts or connectors (this will complete the wiring job).

Advantages and Disadvantages

The advantages of the timer switch include the following.

  • Its installation is easy and simple to use.
  • These time switches are strong, reliable, and low-cost.
  • They give several options and are available with sensors.
  • They have a visually appealing design & slimmer.
  • Flexible and safe.
  • These switches are helpful in connecting Christmas lights automatically.
  • Power and money can be conserved.
  • The travel experience can be enhanced.
  • Farm productivity can be improved.
  • Turn lights ON & OFF at fixed times.
  • Timely alerts can be obtained.
  • Appliances can be managed bitterly.

The disadvantages of timer switch include the following.

  • Timer switches need maintenance otherwise, the dirt can cause damage to the switch.
  • If these switches are used outdoors, there is a chance to get damage based on surrounding conditions.
  • The mechanical time switch controls manually.
  • The mechanical time switch needs different switchboards.
  • Digital time switches require some advance plan before installing at home as they will not be equivalent to normal switchboards.


The applications of time switch include the following.

  • Time switches are used in the packing machine to warm up the machine.
  • This switch is used to regulate water pumps in swimming pools.
  • An electromechanical time switch is used to control the pump that circulates the water.
  • The convectors are automatically changed by this switch based on the selected program.
  • Irrigation pumps can be controlled in the garden with programmed time settings.
  • These switches are used in accessing areas throughout the night to avoid unauthorized persons otherwise animals.
  • A two-channel digital time switch is used to control the heating & lighting systems.
  • The systems used in the fountains to force the water are simply controlled through time switches to create an elegant water spray & a sparkling waterfall in a very simple way.

Thus, this is all about an overview of a timer switch – working with applications. A time switch operates an electric switch which is controlled through the timing mechanism. Using these switches there are many benefits like convenience, more security, safer, savings of energy, and cost. Here is a question for you, what is a 555 timer?