Their main function is to either let current flow from a power supply to a device, or break the flow of current. 

But, can a toggle switch produce a digital signal? A toggle switch is analog by nature and cannot produce digital signals. However, when used as an input with a device like a microcontroller, it can be used to produce digital signals which the microcontroller can interpret as 1’s and 0’s.

Difference between a digital and analog signal

Taking a quick look at the difference between an Analog and Digital signal will help you understand better how a toggle switch can produce a digital signal.

Analog Signal – The best way to look at an analog signal is to look around you at the physical world. The world is filled with analog signals. An analog signal can be best described as a continuous signal. 

Temperature is a great example of an analog signal that is present in the world. It comes in a range of values that can be represented by a sine wave (as most analog signals can be represented by).

Digital Signal – If Analog signals are continuous and have a range of values, Digital signals have two distinct values ; 0 or 1.

When displayed as a graph, digital signals visually represent square waves.  

Digital signals are commonly used for computing and digital electronics which include Microprocessors and Micrcontrollers. 

How toggle switches can be used to produce digital signals

Now, we know the difference between an analog and digital signal, let’s take a closer look at the toggle switch and how it can be used to produce a digital signal.

The main purpose of a toggle switch is to either allow or block current flow from a power supply (like a battery) to a device it is powering.

Below is a diagram depicting a simple circuit of a power supply, toggle switch and load.

In diagram A the toggle switch is open, and therefore no current can flow from the power supply to the load.

The toggle switch in diagram B is closed, and therefore current can flow through and power the load.

With this basic understanding, we can see how a toggle switch can be used to produce a digital signal below.

A toggle switch used with a microcontroller to produce digital signal

A toggle switch cannot produce a digital signal by itself, however, when used with a digital device like a microcontroller, it can be used in a configuration that allows the microcontroller to interpret the information sent from the toggle switch as a digital signal.

Microcontrollers have input ports that have the ability to interpret information from the external world through  input devices like sensors, buttons and switches.

Since a microcontroller is a digital device, it needs to do its computation using 1’s and 0’s. However, it deals with many analog devices. 

One feature that a microcontroller has is to interpret a voltage at its input. However, it should be noted, the voltage should not exceed the microcontrollers supply voltage. 

The most common operating voltages of microcontrollers are 5 volts, so, for the examples below I will use 5 volts. 

Below are two diagrams of a microcontroller and its input. In the first diagram (diagram A) one of the inputs is tied to ground, therefore there is no voltage present at the microcontroller input. In this instance, the microcontroller reads this as a digital value of 0.

The second diagram (diagram B), has the same input tied to the supply voltage (5 volts). Now, there is a voltage of 5 volts present at the input, and therefore the microcontroller reads this as a digital value of 1.

Two configurations a toggle switch can be used to produce a digital signal

So, how does the toggle switch play a part in producing a digital signal with the microcontroller?

There are two configurations that a toggle switch can be used in to produce a digital signal to a microcontroller ; Pullup and Pulldown. 

In both these configurations a resistor (usually 10k) is used.

Pull-up configuration

The first configuration a toggle switch can be used to produce a digital signal is in the Pull-Up configuration as seen below.

In this configuration the resistor is connected to the supply voltage (5 volts), and the toggle switch is connected to ground.

When the toggle switch is open, the 5 volts is present at the microcontroller and therefore it reads this as a digital signal of 1.

Closing the toggle switch will tie the microcontroller input to ground and therefore present a digital signal of 0 at the micrcontroller’s input.

Pull-down configuration

The second common configuration a toggle switch is used to provide a digital signal is known as Pull-Down seen below.

The resistor in this configuration is connected to ground and the toggle switch is connected to the supply voltage.

When the toggle switch is open, the microcontroller is tied to ground and therefore reads a digital signal of 0.

Closing the toggle switch will present the supply voltage at micrcontoller’s input which it will interpret as a digital signal of 1.

Which of these configurations is best to produce a digital signal?

The toggle switch can be used in either configuration to produce a voltage at the input of the microcontroller which can be interpreted as a digital signal.

One is not better than the other. It really depends on your needs. 

If you require the input of the microcontroller to be a digital signal of 0 when the toggle switch is closed, then you would set your toggle switch in the pull-up configuration.

However, if you require the microcontroller input to be a digital signal of 1 when the toggle switch is closed, then you need to set the toggle switch in the pull-down configuration.

Are toggle switches digital or analog?

A toggle switch consists of mechanical moving parts and is used in many primarily in analog circuits to prevent and allow the flow of current. 

Due to this, the toggle switch is an analog device, however, as you have seen, it can be used to provide a digital signal when used with a digital device like a microcontroller which can interpret the voltages at it’s inputs as digital signals of 0’s and 1’s.

Why is a toggle switch used to give a digital signal?

So, a toggle switch has the ability to be set up in a way that a microcontroller can interpret it as a digital signal. 

But, what is the main purpose of this? 

There are many different applications that this proves useful. One of them is a State Machine. 

If one toggle switch is used, you have the ability to create 2 different ‘states’ (or modes) that your program can operate under. Closing and opening the toggle switch will provide a digital signal of 0 or 1 (depending on the configuration) which can switch between states. 

Another application where a toggle switch can be used to give a digital signal is conditional statements. 

Conditional statements execute code depending on certain ‘conditions’. These conditions can be external like whether a toggle switch is a digital level of 0 or 1.

The post Will a toggle switch give a digital signal? appeared first on Electronic Guidebook.

There are multiple types of toggle switches available, and some even come with a light source (LED) embedded in the switch.

But, will the light on the toggle switch drain the battery? The light on the toggle switch will not drain the battery because it draws minimal current from the battery source. The light source is a Light Emitting Diode (LED) which is a very efficient light source, and requires low currents to operate.

There are some instances where the light might possibly drain the battery. This is only if the battery source has a smaller current capacity.I will discuss these possibilities later. 

Why the light on the toggle switch will not drain the battery

A toggle switch is a great addition to any project. 

It uses a rocker type contact mechanism which gives it a great tactile feel, and provides some satisfaction when turning a circuit on or off.

Some of the toggle switches even come embedded with a light (LED), that illuminates when the toggle switch is active. 

However, you might be concerned whether that light will drain your battery. To know for sure whether it will drain the battery or not we need to take a deeper look at the light source as well as the battery.

Deeper look at the light of the toggle switch

First let us take a deeper look at the light used to illuminate toggle switches. 

Light Emitting Diodes (LED) are the go to choice for providing illumination. 

It is a semiconductor light source that lights up when a current flows through it. They come in a range of sizes and colours.

They are slowly starting to replace conventional light sources (such as bulbs) as they require far less power to operate making them very efficient. 

Below is a simple circuit of an LED with a series resistor connected to a battery source. 

The voltage ratings for LED’s vary from one LED to the next.

But, one thing that is constant is the current draw. The current draw values tend to be between 20mA – 30mA. This is known as the maximum continuous current rating.

The closer the current is to the maximum current rating, the brighter the LED will be, and the lower the current the lower the brightness.

The series resistor is used to limit the current flow to the LED, and changes depending on the voltages used.

This current draw is for standard sized LED. 

The LEDs used in toggle switches (commonly known as indicator LEDs) are much smaller and draw far less current compared to a normal size LED. 

The current draw of these indicator LEDs can be as low as 100uA – 2mA. 

As you can see, the current is very minimal and will not drain a decent sized battery. 

Does type of  battery determine if the toggle switch light will drain it faster?

Lets, take a look at the battery. I just mentioned above that indicator LEDs draw minimal current and will not drain a decent sized battery. 

What does that mean? 

Batteries come in a variety of sizes, current capacities, discharge rates,voltages and chemical compositions.

To better understand if the indicator light will drain the battery you are using, you will need to know one thing about the battery you are using, its Capacity.

Capacity

The battery capacity is how much charge the battery is capable of storing. It is typically measured and denoted in Amp-hours or Milliamp-Hours.

To determine how long a battery will last we simply divide the Amp-hour rating by the current draw.

For example, some coin cell batteries are rated for 1Ah (1 amp-hour). So, if we assume the battery is connected to a standard sized LED (which draws 20 mA), the battery will be able to power it for 50 hours (1/0.02). 

We need to convert the 20mA into Amperes, so that is where we get the value of 0.02.

If we use the value of 2mA (standard current draw of light used in toggle switches), the battery will be able to power the light for 500 hours! 

Thats plenty!

So, when it comes to the question of will the light of the toggle switch drain your battery, it really depends on the capacity of your battery.

The higher the capacity of the battery the less affect the light of the toggle switch will have. However, if the toggle switch light is being powered by a low capacity battery, the chances of it draining the battery are higher.

While the current draw of the indicator light (LED) is minimal, if a battery with a very low capacity is used, it might possibly get drained.

However, if you are powering it with a standard sized battery, the toggle switch light will not drain the battery unless left on for days on end.

Why is a light used on the toggle switch?

So what is the main purpose the light is used on the toggle switch? The main reason for using the light is for indication purposes. 

It provides a visual cue that lets you know the state of the toggle switch. The light will illuminate when in the on position.

Having a visual representation of whether the toggle switch is the on position or not can benefit you in many ways. 

One of them being safety. You can easily tell what state the toggle switch is in by looking at the light. If you were supposed to switch off but forgot, a quick glimpse will give you an indication.

Other than safety, having a toggle switch that lights up is just cool! 

It can add some aesthetics to your project, and look awesome during the night time.

Can you get a toggle switch without a light?

You might have purchased a toggle switch with a light embedded in it without really wanting a light.

Are there toggle switches that do not have a light? Yes. The standard toggle switches come without any light embedded in them.

So, if you are looking for a toggle switch without any light, make sure to check the specifications on the product page of the website you are buying them from. 

Does the size of the battery matter if it will get drained by the toggle switch light?

As you saw earlier, the capacity of the battery is a major indication of whether it will get drained or not. 

The dimension of the battery does not necessarily have a proportional relationship with the capacity. What I mean by this is that, just because a battery is bigger, does not mean it has more capacity. 

Sometimes smaller batteries have more capacity than larger ones. It all comes down to the chemical composition.

So, when choosing a battery to power your project with a toggle switch that has a light, make sure to choose a battery that has a high capacity (amp-hours or milliamp-hours) to ensure it will not get drained. 

Do not select a battery based on its physical dimensions.

How to test how much current the light on the toggle switch is drawing–

Every toggle switch that has a light will draw different amounts of current. While the standard current draw is about 2mA, it can be handy to know the exact number so you can pick a battery accordingly.

To calculate the current draw of the toggle switch you have, you will need a multimeter capable of measuring current and place in series with the terminal that has the light connected to it as seen in the diagram below.

Make sure to only connect the switch when testing. Turn the switch on and check the multimeter reading to see how much current the light of the toggle switch is drawing. 

However, caution should be taken as you are directly connecting the positive terminal or the battery to the negative. So, keep it on for a very small amount of time.

What if the light of the toggle switch is draining the battery

What if you notice the toggle switch light is draining the battery but you still want to use the light?

Your best option here is to replace your current battery and purchase a battery with a higher capacity.

Can you disconnect the light from the toggle switch to drain less from the battery?

The most standard simple toggle switches that come embedded with a light have only 3 pins.

With this configuration, there is no way to disconnect the light (unless you open up the toggle switch and physically disconnect the LED circuit inside).

There are other types of toggle switches that have 5 pins. 

Here you have the option of using the embedded light or not. If you don’t want to use the light you skip wiring the LED+ and LED- pins.

Do you need to wire a series resistor for the toggle switch light?

The toggle switch has maximum current and voltage rating so the LED inside the toggle switch comes with its own series resistor to protect the LED from those maximum voltages and currents, so no external series resistor is required.

However, if you want to dim the light further, you can add a series resistor. 

How to wire up toggle switch that has a light

If you have a three pin toggle switch which has a light, and are a bit confused how to wire it, the video below explains it well.

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