I always fancied building projects that solves practical problems. And here the problem is, I have this bad habit of misplacing things like my Coffee cup, Notebook, Pen stand and such. This often led me to waste so much time searching for these things when I need it. So in order to resolve this I decided to build a simple project using Infrared that alerts me when I take these things out of its place. And it should keep on alerting me until I place it back in its position. And it did helped me to keep my stuffs organized and helps me to avoid wasting my time in searching for these.
I want to keep this project really simple allowing anyone to build it. So I have built this with discrete electronic components and couple of IC’s without using any Microcontrollers.
HOW IT WORKS:
In this project we are going to transmit Infrared beam from an IR source and use a receiver on the other side at a certain distance from the receiver. In the path of IR beam intended objects will be placed. When object is placed it blocks the IR beam from reaching the receiver. When the object is removed from the path IR beam, it reaches the receiver and this triggers the Indicator to alert the user that the object is misplaced.
- IC 555
- Resistors ( As required )
- Capacitors ( As required )
- Connecting wires
- Infrared LED
CIRCUIT DIAGRAM OF INFRARED TRANSMITTER:
The working of this project starts with IR transmitter unit. Here a simple IR LED is used to transmit IR beam. This IR beam will be used to detect the things placed in it its path. Remember IR beam travels in a straight line and easy to create making it an optimal choice for our project.
CIRCUIT DIAGRAM OF IR RECEIVER AND MULTIVIBRATOR:
In this part of circuit IR beam produced from transmitter circuit is detected using Photodiode. By this way it will help us to detect the objects placed in the path of IR beam. Photodiode offers high resistance and blocks the current flow when there is no IR beam incident on it. When IR beam falls on it resistance drops and as a result current starts flowing through the diode. Now voltage drop occurs across the diode and it is fed to the Non inverting input of Opamp. To generate the reference voltage another set of voltage divider is formed using the resistor R2 and preset resistor R3. The reference voltage from the voltage divider is fed into the inverting input of Opamp. The preset R3 should be adjusted to provide the reference voltage lesser than Photodiode and R1 divider pair when IR signal is incident on Photodiode.
When the IR signal is blocked by any object ( Object of interest cups, pen stand etc ) the voltage in the inverting input will be greater than non inverting input. But when the object in the IR signal path is removed voltage drop occurs and across Photodiode and now voltage in the non inverting input will be greater than voltage at inverting input. This will force the opamp to give high signal at the output.
The next stage of the circuit is an Astable multivibrator built using IC 555. As we all know Astable multivibrator is used to generate square waves at a certain frequency and this is what it exactly does in this circuit. But the only difference here is that output from Opamp is fed to reset pin of IC 555. So as long as the object stays in the path of IR, output of Opamp will be low which will keep the astable multivibrator output in low state. When the object is removed Opamp output goes high which will pull the reset pin to high and multivibrator will start emitting square wave in its output.
The purpose of square wave is meant to drive a LED ( in my circuit ) which in turn will flicker and serve as an indicator for the user. This is because a flickering LED is likely to grab user attention than continuosly lit LED ( and it worked in my case). The frequency of Astable multivibrator depends on the value of Resistor R3 and Capacitor C4 which is really not critical in this project since all I want was to generate a signal which produces visible flicker with the LED.
Now the output from Astable multivibrator can be used to feed the indicator of your desire. An indicator here is basically a component that is capable of alerting you when the things are out of place. There are number of options you can choose from. Buzzers, Speakers, LED’s, Motors are some of the few choices for indicator in this circuit. However if you are planning to keep it simple use either LED or Buzzer in the output pin of multivibrator. Since these two components consume less current IC 555 should be able to drive them directly. If you want to use Speakers or Motors you may need to add switching transistors along with the output of IC 555.
Buzzers tend to be annoying over a period of time so I stick with LED in this project to act as an indicator to alert me whenever I take the object out of place.
SETTING UP THE CIRCUITS:
I have made a small platform to place the objects that needs to be monitored, however you can fix these circuits to the ends of table or anywhere you see fit as long as the receiver is within the range of transmitter. And you will get a comfortable range of about 2 meters with this circuit. The IR transmitter and receiver should be arranged in a way IR beam travels in straight line and incident on Photodiode when no object is placed. From the Multivibrator output wire a Indicator LED ( or any other indicators of your choice ) and fix it in wall or anyplace where it is visible to your eye and grabs your attention easily.
I have left a space of about 15cm between IR transmitter to receiver which is suffice in my case you can leave more room for your object to place since you have range of about 2 meters. Fixing the transmitter and receiver to the ends of your table will make your task easy and gives more room for your object.
I have built this project on a general PCB but if you want this project to have a more professional look and easy assemble. You can download the gerber files for this PCB design below.
PCB design of Things organizer using Infrared beam.
|Date:||February 10, 2019|
I would recommend you to order PCB’s from JLCPCB for their superior build and quick turn around time. You can order the above PCB boards IR transmitter & IR receiver and Multivibrator directly using these links.
WORKING AND SETTING UP VIDEO:
- Arranging Infrared LED and Photodiode next to each other and detecting the reflected IR beam as we see in most IR detection modules is not effective in this project since reflection of IR beam depends of factors like color of reflecting object and distance. It tends to fail for all the objects with dark colors. This placement proves effective.
- You can increase the space for your objects by placing the transmitter and receiver at even further distance but should always be aligned in a straight line.
- We can 3D print case for these modules and make it look good.
- Get creative with your indicators and its placement that will suit your need.
This is a simple project that can probably help you to be organized. Here you can take a look at some of our other Infrared based circuits and projects in this website. Hope you guys find it interesting. I would love to hear your feedback and comments about this project. Happy DIY project building 🙂
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