A light sensor helps detect changes in light. 

Having the ability to sense the change in light has many advantages and can be utilised a countless of different ways.

But where are light sensors used? Light sensors are used in many different industries and for a number of different applications. They can be found in consumer electronics like Mobile phones and Tablets, Streetlights, Automobiles, security systems just to name a few of their applications. 

What is the purpose of light sensors?

Thanks to advancements in technology we have a range of sensors available at our disposal. Depending on your needs there are sensors that can sense  temperature, speed, humidity, gas, angles etc.

The light sensor is one of the many sensors available.It is a device that has the ability to convert light (which are photons) into electrical energy (in the form of electrons). 

It’s main purpose is to detect changes in light level, and sees it used in many different applications where light intensity is a major component of the application.

I will cover the common applications where light sensors are used later in this article.

Different types of Light Sensors

With light sensors, you have three types available. They are the Photoresistor, Photodiode, and Phototransistor. 

Photoresistor

A photoresistor light sensor is the most commonly used light sensor. It is used by hobbyists and makers due to its low price and availability. It is also known as a Light Dependent Resistor (LDR). The photoresistor varies its resistance depending on the intensity of light it detects.

The higher the light intensity of light, the lower the resistance, and vice versa. 

Photodiode

While the resistance of a photodiode light sensor varies depending on light levels, a Photodiode produces a varying electric current depending on the intensity of light. 

Brighter light levels cause a greeted current flow and vice versa. 

Phototransistor

The final type of light sensor is the Phototransistor. The phototransistor has the same working principle as the Photodiode, but with the added benefit of an amplifier. 

Due to this amplifier, the phototransistor has better light sensitivity. The downside is that it doesn’t do too well in lower light applications. 

Can light sensors work by themselves?

No, light sensors only have the ability to detect changes in light and output this information in the form of a voltage or current. They cannot do any processing on the information they detect. 

Let’s take one of our five senses as an example. Our eyes let us sense the world around us visually. They have the ability to take in information. But, to make sense of that information we require a brain.

This is the same of light sensors. They require a brain, which can either be a Microcontroller or Microprocessor which are devices capable of taking the information that a light sensor outputs and processing it accordingly.

Applications of where light sensors are used?

You might not think that a light sensor has many uses, but it is a very versatile sensor that can be found in many applications. 

Below I have listed applications where light sensors are used. 

Application #1 where light sensors are used: Consumer Electronics 

The most common consumer electronic devices that use light sensors are Mobile Phones, and Tablets.

The light sensor is used in these devices to help with the auto-brightness function for the display. This is an essential function because the light sensor detects the light levels of the environment the user is using the device in and can adjust the brightness automatically. 

If the light sensor detects the environment to be dark, the brightness of the mobile phone and/or tablet does not have to be very high, so the brightness of the display can be reduced.

On the other hand, if the light sensor detects higher levels of light intensity, this will make it harder for the user to read the display and therefore the brightness of the device’s screen is increased. 

Application #2 where light sensors are used: Automobiles

You might have experienced driving in the night and noticed an oncoming car with their headlights off. Or, you might have been the driver who forgot to turn your headlights on.

Not turning your headlights on while driving at night can have devastating circumstances. You are essentially invisible to other drivers, and pedestrians.

Older models of cars did not have the ability to automatically turn on its own headlights if the driver forgot to do so. 

Newer cars are now capable of automatically turning on their headlights when ambient light levels drop (or you enter a tunnel) thanks to light sensors. 

Application #3 where light sensors are used: Streetlights

Headlights on cars help illuminate the road better, giving the driver better vision at night, and also giving other drivers and pedestrians better view of the car. 

But, there is only so much that a car headlight can illuminate the road. 

Another way of helping the drivers with night time driving is the use of Street Lights. They also help illuminate roads which help the driver see where they are going. 

Streetlights are also beneficial for people walking on footpaths. It lets people see where they are walking and helps them avoid any potential obstacles. Also, walking in the dark can be quite daunting. Having footpaths that are lit gives pedestrians a bit more reassurance.

Turning on streetlights manually every night is very inefficient. Also sun rises and sets at different times everyday.

Using light sensors allows them to turn on and off at the right time everyday. This also helps save electricity.

Application #4 where light sensors are used: Security

There are many forms of security systems to help keep you and your personal things safe. 

Lasers are often used in security because their beam is invisible to the naked eye. You can create a barrier of sorts when you use a laser in combination with a light sensor.

They are often used at the entry of stores and workplaces which lets owners know when someone has entered. 

Application #5 where light sensors are used: Horticulture

Plants and trees are essential to life. Without them we would not survive. They provide us with Oxygen that helps us breathe, as well as food to feed us. 

Growing plants, and trees is not a simple task. It requires a lot of care and thought like choosing the right soil to plant seeds, how much water to use and how much sunlight the plant receives. 

If a plant is left out in the burning sun without getting watered, the plant will get dehydrated and die. 

So how do light sensors help in the field of horticulture?

They are connected to sprinkler systems. The light sensor detects when the sun is at its brightest and activates the sprinkler system to ensure that plants and trees do not get dehydrated. 

They work in concert with other sensors to ensure that the right environment is created to allow plants and trees to thrive. 

Application #6 where light sensors are used: Safety

A fire can consume a house or workplace in a matter of minutes. No matter what time of the day, fires can be very dangerous.

But, they pose even more of a risk during the night when you are sleeping. A fire can start while you are asleep and you will not even be aware of it.

Smoke detectors were designed to alert you when a fire is present. There are many different types available, and one common type is the Photoelectric Smoke Detector. 

It uses light sensors to detect fires. The working principle is similar to that of the laser beam and light sensor mentioned above for the security system. An LED shines a beam of light inside the smoke detector toward the light sensor. When smoke disturbs the beam an alarm is sounded. 

Application #7 where light sensors are used: Medical 

Advancements of technology in the medical field have given us many life saving devices. 

Sensors play a big role in many of the medical instrumentation. 

Light sensors are used in devices such as the Pulse Oximetry (which helps measure the percentage of Hemoglobin) and Heart-Rate monitors (to measure heart rates). 

Application #8 where light sensors are used: Solar

Renewable energy is now becoming the new way of powering our world. It is more sustainable and better for the world. 

There are many different types of renewable energy and one abundant source is the Sun. 

Solar panels convert sunshine into electrical energy which then gets stored for later use. 

However, the sun does stay stationary in the sky. It moves across as the day goes by. In order to get the most energy from the sun, solar panels need to be positioned so they directly face the sun. 

But, they cannot do this on their own. Light sensors lend their helping hand by detecting where the sun rays are at their brightest and then position the solar panels accordingly to get the most out of the sun rays. 

Which type of light sensor are used in these applications?

I mentioned earlier the different types of light sensors, Photoresistor, Photodiode, and Phototransistor. I’ve covered some of the common applications where light sensors are used. 

Each type of light sensor has its advantages for different applications. 

Where are Photoresistor light sensors used?

Photoresistors are commonly used in applications where a slow response in light levels are sufficient such as turning on street lights, solar and horticulture applications.  

They are also great for lower light levels. 

Photoresistors are the go light sensor for hobbyists due to their ease of use, and low cost. 

Where are Photodiode and Phototransistor light sensors used?

When light levels change faster, and a quicker response is needed, Photodiode and Phototransistor light sensors are used. 

They are used for higher, more intense light levels.

Applications in the Medical Field, Smoke Detectors, Automobiles, Compact Disc Players etc use these kinds of light sensors. 

Where you wouldn’t use light sensors?

There are many different applications that require the help of some kind of sensor to detect a physical phenomenon like temperature, speed, gravity, etc.

Since there are so many sensors available, a light sensor wouldn’t be used for all of them. They would only be used where light is the main thing being measured. 

You wouldn’t use a light sensor to measure the temperature of a room. The need for a light sensor will present itself.

Final thoughts

Light sensors are a great and versatile tool that see them being used in many different applications across different industries such as Medical, Horticulture, Security, Safety and more. 

There are three types of light sensors used (Photo-resistor, Photo-diode, and Photo-transistor), each with their own advantages depending on the need of the application.

The post Where are light sensors used appeared first on Electronic Guidebook.

The light bulb enabled people to light up their homes more efficiently than having to use candles.

Over the past decades however, the discovery of Light Emitting Diodes (LED’s) have proven to be more effective and efficient (about 90% more efficient) than their older incandescent counterparts.

While LED light bulbs do have a longer lifespan, they will eventually stop working and need to be disposed of.

But, how do you dispose of LED light bulbs properly?

The great thing about a LED light bulb is that over 95% of it can be recycled. Since LED light bulbs contain electronic components, it can be disposed of to a dedicated electronic waste (e-waste) recycling facility. 

LED light bulbs can be known for containing nickel and lead.

If not disposed of properly these harmful elements can be detrimental to the environment and people’s health. 

What is E-waste

Electronic waste or better known as E-waste, are products that include electrical or electronic components that are no longer wanted or needed and need to be disposed of.

This can include things like your old tv, mobile phones, stereos, computers etc.

Why is it important to recycle e-waste?

Many, if not all electronic waste contain hazardous materials.

These hazardous materials include, lead, cadmium, and beryllium

If not properly disposed of, they make their way to landfills where they leak these hazardous materials into the ground and waterways which can lead to the sea as well as our drinking water.

Also, most of the trash in landfills gets sent to third world countries where children scavenge through these hazardous materials for metals putting their health at risk. 

LED light bulbs are not as hazardous as many other electronic products, but do contain nickel and lead. 

So, disposing of them the right way will be beneficial to the environment and human health.

How to dispose of e-waste?

We all know that there are recycling facilities that deal with recyclables such as paper, cardboard, plastic, and glass. 

Most of us have a recycling bin at home that we throw those items into. 

But, recycling your old LED light bulb does not mean just throwing it in the recycling bin you have at home.

Doing so will add more work for the people at those recycling facilities as they will have to separate e-waste from the items they can actually recycle (paper, cardboard, glass).

Electronic waste like LED light bulbs, need to be broken down and sepearted because not all parts of it can be recycled.

There are dedicated e-waste recycling facilities that deal primarily with electronic waste like your LED light bulb.

Where can you find an E-waste recycling facility?

I cannot know for certain if there is an e-waste recycling facility in your city, but the best way to find one is to do a quick google search for ‘e-waste recycling near me’ or instead of ‘near me’ you can insert the ‘city’ you live in.

The search results will list all the available recycling facilities near you.

Another alternative is to check with the vendor whom you are buying the LED light bulb from, if they take old LED light bulbs to be recycled.

Most vendors nowadays encourage customers to return old electronic products so they can recycle and reuse components. 

Does it cost to recycle a LED Light Bulb?

Electronic waste that usually incur a fee are bigger products like TV’s.

However, there is no standard rule, and it all depends on the e-waste recycling facility. 

What is an LED light bulb?

An LED light bulb is a more efficient means of illuminating a space compared to its older counterpart, the incandescent light bulb.

It is rapidly becoming the choice in households, businesses and street lighting.

LED light bulbs use Light Emitting Diodes.

When a current is passed through the light emitting diode, photons are released in a process known as illuminessence resulting in the light we see. 

Why is a LED light bulb considered e-waste?

Above, you saw the importance of recycling products that contain electronics as it reduces the harm on the environment and allows us to reuse items.

But, why is an LED light bulb considered electronic waste?

What does an LED light bulb consist of?

The reason that an LED is considered electronic waste is the simple fact that it contains electronic components.

Inside an LED light are the following circuits and electronic components:

• Light Emitting Diodes (LED)
• AC to DC converter
• Capacitors
• Resistors
• Transformer
• Diodes
• MOSFETs

LED light bulb circuitry varies in complexity from one bulb to the next, but these are the common components that can be found inside your standard LED light bulb. 

This is why it is vital to dispose of them by recycling them at dedicated e-waste recyclers. 

Average Lifespan of an LED Light Bulb?

The even better news to the fact that you can recycle your old LED light bulbs when disposing of them, is that they have a long lifespan.

The average LED light bulb lasts up 25,000 hours. 

That’s about 1041 days!

Different types of LED light bulbs

Below are a range of different types of LED light bulbs:

• E27 
• E14
• B22
• B15
• R50
• R63
• PAR38

The process of disposing of any one of them is the same.

Conclusion

So, to reduce the harmful impact that e-waste has on our environment as well as our health, the best way to dispose of that old LED light bulb is to take it to a dedicated e-waste recycler.

They will be able to break down the LED light bulb and recycle materials.How to dispose of LED light bulbs ?

The post How to dispose of LED light bulbs? appeared first on Electronic Guidebook.

Compared to the older conventional light bulb, LED lights are much more efficient and have a longer life span.

They come in a variety of forms such as bulbs, strips, flat panels, or just the individual LED itself. 

You are not limited to the color options as LED’s have a multitude of colours to choose from (colours that cover the entire color spectrum visible to the human eye).

Dimming the lights is a great feature to have in rooms off your home. It can provide a different ambiance and set the mood for different occasions.

So, can you dim LED lights?

Since there are many types of LED lighting options available, it all depends on what kind of LED lighting is being used.

For LED light bulbs, which are connected to light sockets in your home, most LED light bulbs are dimmable. However, not all of them are, and they do not all operate in the same way.

You then have your LED strips, and individual LED’s that run on lower voltages and do not get connected to light sockets. These types of LED lighting can be dimmed by simply lowering their voltage (or connecting to a controller circuit that can dim them).

Since you cannot lower the voltage of a LED light bulb, you need special dimmer switches to carry out this task.

In this article I will dive deeper and cover more information regarding what kinds of LED light bulbs you can dim and what is involved in dimming them.

What is dimming?

Dimming a light is essentially the ability to change its brightness.

A normal light in a household which does not have a dimmer circuit, would be operating at its maximum brightness when turned on.

Dimming allows the brightness to be varied from 100% all the way down to 0% (which looks like it is turned off but it is not). 

Sometimes having the lights at full brightness can be quite annoying as they can have an effect on your eyes overtime. Having the ability to dim a light source can be beneficial. 

By dimming the lights you lower the amount of power consumed by the light therefore cutting costs to your power bill.

What is a dimmer?

Being able to dim your lights does not just happen by magic.

It involves something known as a dimmer circuit. Their purpose is to allow you to be able to alter the brightness of your lights. 

The way the dimmer circuit does this is by changing the voltage waveform applied to the light. 

The dimmer circuit rapidly shuts on and off, reducing the total energy that the light bulb receives. The lower the energy the lower the brightness and the higher the energy the brighter the light bulb.

Dimmer circuits are generally used for light outputs that include incandescent bulbs, halogen bulbs, compact fluorescent lights and Light emitting Diodes (LED’s). 

Older dimmers were built using resistors. Resistors are not the most efficient way of dimming circuits due to the fact as the resistors heat up, a lot of energy is lost. 

Therefore, modern day dimmers are built from semiconductors to increase the overall efficiency.

Types of Dimmers

Through the years the dimmer has seen many upgrades from its humble beginnings. 

It all started with the Rheostat Dimmer. This type of dimmer primarily used a rheostat (of course!). 

A rheostat is an electronic component used to control the flow of current by varying its resistance.

This type of dimmer was inefficient because a lot of power was lost through heat. They were large and needed cooling air to reduce the heat.

Also, due to the fact they had mechanical parts, they were slow, again adding to its inefficiency. 

A common early use of a Rheostat dimmer was the Saltwater Dimmer which used a liquid as a form of varying its resistance. 

Next came the Auto-transformer dimmer. Also sometimes referred to as a VARIAC.

Though the Auto-transformer was as large as a Rheostat dimmer and were quite similar in resemblance, they were more efficient.

The output voltage which is used to vary the brightness of a light, was independent of the load applied in an Auto-transformer. This led to easier design of the lighting.

Nowadays, Auto-transformers are no longer used for dimming applications.

Lastly we have the Solid-State Dimmer. The solid state dimmer uses semiconductors to perform dimming. 

They were developed in large part to reduce the problem of inefficiency that were present in the Rheostat and Auto-transformer dimmers. 

The main benefit that reduces the dissipation of power is that solid state dimmers switch the voltage rather than absorb it.

It also has the added benefits of being controlled remotely and small enough to be embedded inside a household light switch.

Application and Benefits

Having the ability to dim the lights can have many advantages.

Light levels in a room can affect your mood without you even knowing. It affects things like the way we work, and the way we feel. 

The softer the light level the more comforting and relaxing. While brighter light levels are more stimulating and good for keeping you awake.

Softer lighting is great for setting the mood for things like watching a movie, or having a romantic dinner with a loved one. Or, maybe you are someone who likes sleeping with the lights on. A softer light will solve this problem and eliminate having to try to sleep under light that is at full intensity.

Brighter lighting is great for when you need to do work or need a good amount of light for reading.

Having different rooms that have different light levels is not ideal, but, the light dimmer is the perfect solution.

You can have the benefits of softer and brighter lighting all in one room.

The Light Bulb

One of the main pivotal points in history was the invention of the light bulb. We can thank Thomas Edison for that. 

Before the light bulb people would use candles to light up their homes so they could carry out tasks like cooking, bathing, reading etc.

While candles were handy, they were not the most effective, as they only lit small spaces at a time.

Light bulbs allowed one to light up more areas in their house at the flick of a switch.

The dimmer circuits that we have covered were used in conjunction with these older incandescent light bulbs. 

Over the years however, light bulbs have evolved from the older incandescent bulbs to newer more efficient Light Emitting Diodes. 

Light Emitting Diode

If the incandescent bulb was a crucial invention in lighting, the Light Emitting Diode (LED) was a crucial innovation.

Compared to Incandescent, Halogen and Compact Fluorescent bulbs, LED’s require far less energy to operate.

They use 75% less energy to run. This means that in the longer run you save more money on your power bills. 

They also have a longer life span, again saving you money by having to buy less of them.

A LED is a tiny semiconductor known as a Diode. A diode is a device that restricts the flow of current in one direction.

This flow of electrons creates photons (which is the light we see).

LED Light Bulbs

So, you can see the many benefits of using a LED light bulb.

But, can you dim all LED light bulbs?

It all comes down to two factors; whether the LED light bulb is designed to be dimmed and whether your dimmer is LED compatible.

Not all LED light bulbs are designed to be dimmed. The ones that can be dimmed are designed with a special circuit embedded inside them that allows their brightness to be varied in response to a varying current.

So, your ability to dim a LED light bulb all depends on this factor. When buying a LED light bulb, you need to verify that it is ‘dimmable’. 

Most of them will state this in the title, or you can check the product description.

So you have a dimmable LED light bulb. But, what about your dimmer circuit, will it be able to dim them?

There are two types of dimmer circuits; Leading Edge and Trailing Edge.

Leading Edge dimmers are designed to work with older incandescent bulbs. These sort of dimmer circuits would be found in older households. 

These types of dimmers were designed to work with traditional bulbs due to the fact that they were higher wattage. Since LED light bulbs are low wattage leading edge dimmers will not be able to dim your LED light bulb.

Trailing Edge dimmers are designed to work in the lower wattage range and therefore can dim LED light bulbs (the dimmable ones of course!). 

How do you tell if you have a Leading or Trailing Edge dimmer? 

Since, dimmer circuits deal with high voltages, it is not advisable for you to open your light switches and check.

You will have to contact the manufacturer to find out what kind of dimmer circuit you have installed.

You could get an electrician to come and have a look as well. Or, you could just install your LED light bulb and check if the brightness of the light is varied. The worst that could happen is that you blow the bulb.

If your home was built within the last 5 years, and you have a dimmer, it is likely that it is a trailing edge dimmer and compatible with LED light bulbs.

If you have identified that you have a Leading edge dimmer do not worry, you can make the switch (pardon the pun) to a Trailing Edge dimmer.

The cost can range from $60 to $150 and depending on the brand of the dimmer and the cost of labor.

As I mentioned before, for your own safety, it is advisable to hire an electrician to remove and install the new dimmer.

Conclusion

So, in order for you to be able to dim an LED light bulb, it needs to specifically designed to be dimmed.

You can find this information in the product description of the LED light bulb in question.

Also, your dimmer circuit needs to work in conjunction with LED light bulbs.

These dimmers are most commonly the Trailing Edge Dimmers.

Always consult an Electrician if you need to check what type of dimmer you have, or, if you want to replace an existing dimmer to the newer ones.

The post Can you dim LED lights? appeared first on Electronic Guidebook.