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Simple Proximity Detector Using IC 555 - Complete Working Description with Schematic

In this article we discus a simple IC 555 based proximity detector circuit which can be used for detecting  human trespassing from a distance.

Simulation and Working


An infrared proximity detector can be considered as one of the most valuable and widely used circuits in electronic automation application range.

We can typically see it being used in automatic water dispensers, automatic hand dryer units and some specific variants may be witnessed in the automatic doors of department stores.

Working principle of the proposed proximity detector circuit using IC 555

In the design a generation of rapid bursts of peak voltage pulses from the IC LM555 is implemented at a relatively lower frequency rate, which is transmitted via the infrared LED as jets of IR beams.

These transmitted pulses are focused toward the area which is required to be monitored, and is reflected back when a subject or intruder is detected over a phototransistor diode positioned strategically for receiving these reflected signals..

Once this happens the received signals go through processing in order to enable an attached relay mechanism and subsequently an alarm device to get activated.

To test the above implementation an object may be introduced across the zone of the IR beams and the response may be checked by monitoring the relay operation, such as by moving hand in the focused area, within a distance of about 1 meter.

When the reflected signals hit the phototransistor, it develops a potential difference across the 1M pot (adjustable) and triggers the associated Darlington stage, which in turn activate the right hand side 555 stage configured as a monostable circuit.

The relay gets activated in response to this and stays ON depending on the monostable predetermined time delay set by the 1M and the 10uF capacitor.

Circuit Diagram



Parts List fro the proposed IC 555 based IR proximity detector circuit.


2-- IC LM 555
2-- IC sockets 8 pin
1-- relay 12 V 5 pin
1-- Infrared Phototransistor General Purpose



1-- Infrared Diode General Purpose



3-- BC547
2-- capacitors. 10 uF / 50 V
1-- 1N4148 diode
1-- red led 5mm
1-- 68 H
1-- 1K5
2-- 10K
1-- 100K
1-- 470 R H All 1/2 W

1-- 10k 1/4 w resistor to be connected in between 1M preset center lead and the BC547 pair

IC 555 Pinouts

IC 555 pinout details, ground, Vcc, reset, threshold, discharge, control voltage

Need Help? Please leave a comment, I'll get back soon with a reply!




Comments

  1. Dear Swagatam,

    What does the H mean with the 68 and the 470 ohm resistor?
    Would 1W or 2W resistor be ok for the ½W resistors?

    Best regards,
    Henrik

    ReplyDelete
  2. Dear Henrik,

    H symbolizes "Ohms"

    All resistors can be 1/4 watt rated.

    You would also want to refer to the following article:

    https://homemade-circuits.com/2015/02/infrared-remote-control-security-lock.html

    ReplyDelete
  3. Dear Swagatam,

    As always a fast reply from you. Thank you.

    ReplyDelete
  4. what's the maximum range (distance) it can cover?

    ReplyDelete
  5. I assembled this circuit on bread board but when supply is on relay get activated and ir receiver get to much hot. I don't know where is problem? can you tell me any test point to check the voltage?
    In this circuit what are the size of IR receiver & transmitter?
    Is this work as PIR sensor?

    ReplyDelete
  6. as i used IR receiver have 3 pinout (OUT GND VCC) in schematic only two legs are shown.

    ReplyDelete
  7. you might have connected the photo transistor directly with the base of the BC547 Darlington pair...this might have possibly damaged the BC547 also.

    connect a resistor in series with the base of the BC547 so that the IR phototransistor does not get loaded to much and the Darlington also stays safe.

    ReplyDelete
  8. please check datasheet of standard IR diodes for the dimensions, PIR devices are different and are designed for sensing human/animal body temperature profile, the above design is based on IR reflection from the subject.

    ReplyDelete
  9. then connect the Vcc to positive, GND to ground and the out to the base of the BC547 via the 1M resistor as given in the diagram.

    Make sure to use a 7805 IC if yuor sensor is specified to work with 5V

    ReplyDelete
  10. https://drive.google.com/file/d/0ByzJSqCugD_yN0hISy1MNWxWWTg/view?usp=sharing
    https://drive.google.com/file/d/0ByzJSqCugD_ySGZUTjBaTEhuR1E/view?usp=sharing
    Sir i used above resistor. How to know what is standard supply for this diode?
    and you used direct 12 volt supply in circuit right?
    and as you mention it possible damaged the BC547. But why relay is activated?

    ReplyDelete
  11. can't predict the specs without seeing their datasheets, .....for safety power the circuit from a 5V source, with 5V the diodes would be quite safe.

    make sure the BC547 base has a resistor.

    if your relay is continuously ON would indicate a faulty 555 IC or some other wrong connection.

    ReplyDelete
  12. Sir,
    I went through your proximity detector circuit .As
    i am new to these circuits i have a few questions about it :
    1- The name of diode below 68H resistor is not
    there . Please tell me.
    2- Above 1M resistor is it a transistor? Its name sir?
    3- The diode below 470H resistor, is it infrared
    diode?
    4- Do I have to connect all the ground connections
    together to the negative terminal of the battery?
    5-Do relay have polarity? How to connect one in this
    circuit?
    6- In the parts list it is mentioned 1 Transistor General Purpose . Does that mean I can use any transistor? I have 2N2222 transistor can I use it and where.
    7-For infrared diode , while buying do I have to ask
    the shopkeeper to give me any infrared diode in the shop?
    8-Where do I connect the green 5mm led mentioned in the parts list?
    Thanks in advance sir. Waiting for your reply. Sorry
    to disturb you sir

    ReplyDelete
  13. shalabh,

    if you are new then this circuit is not for you, you'll not be able to make it for sure!

    anyway,

    1)it's a photodiode, any type will do
    2) it's a phototransisror any type will do
    3) it's an LED
    4) yes that's correct.
    5) for connections check this article:

    https://homemade-circuits.com/2012/01/how-to-understand-and-use-relay-in.html

    6. it's mentioned for phototransistor
    7, yes any type will do, 1 photodiode and one phototransistor
    8. it's the one which is connected with 470 ohms

    ReplyDelete
  14. Dear sir,
    Thanks for your time.
    Maybe I won't be able to make it but still I would like to give it a try.

    1-Can I use an infrared led in place of photodiode. Is it the same thing?
    2-Do diodes have polarity? If yes then which side should the band go for 1N4148 diode? Towards the transistor or +12V supply?
    3-Does the straight line in diode symbol correspond to the band on it?
    4-How do I know pin1,2,3 etc on the ic? I have read some where that on facing the ic towards you so that you can read it, the left most pin is the first pin. And it increases as we go anticlockwise. Is that right sir?

    Thanks in advance for guiding me sir.

    ReplyDelete
  15. 1) yes infrared LED will also do.

    2) diodes have polarity, band side will connect with the positive line.

    3) yes that's correct.

    4) that's correct, 1 starts from left of the "notch" and ends at the right of the "notch" from the printed side, for all ICs

    ReplyDelete
  16. Hi Sir,Could you help me to make a high volt flyback transformer ignition circuit along with hall effect sensor as an igntion trigger switch for my 10CC petrol engine?

    ReplyDelete
  17. Hi Sandeep, I think you can use a motorcycle ignition coil and a CDI circuit along with a pick up coil/magnet set up for your application, the use of a pickup coil in place of a Hall effect sensor eliminates the need of an extra electronic circuit

    The CDI circuit can eb found in this article:

    https://homemade-circuits.com/2011/12/how-to-make-capacitive-discharge.html

    ReplyDelete
  18. sir, could you mention the mechanism of specific part of the circuit, because for my project I need to know each and every detail of it , it would be really helpful if u would mention more details of each and every parts role in it.

    ReplyDelete
  19. the transmitter side 555 is configured as an astable for providing a frequency to the transmitter diode, while the other 555 is configured a a monostable, whose pin#2 is grounded momentarily in response to an intruder reflecting the IR frequency to the IR receiver diode....this toggles the 555 and its relay for a time period determined by the values of 1M, and 10uF parts and then switches it OFF.

    more details than this would be difficult.

    ReplyDelete
  20. Sir for above circuit(proximity detector circuit), what should be the distance between IR transmitter and IR receiver. And is it possible to use 556 instead of two 555

    ReplyDelete
  21. RLF, they can be some inches apart...it's not critical.

    556 can be used

    ReplyDelete
  22. Would the sun light be an issue and get false triggers?

    ReplyDelete
  23. I am sure about that, because sunlight also emits IR rays so it will need to be tested practically

    ReplyDelete
  24. thanks for your post it helpful but what i want to know is this, the component 68H in the circuit above i don't know the meaning

    ReplyDelete
  25. good day sir
    i need to build a circuit for automatic operation of water in wash basin based on ir sensor. can i use this circuit to drive 12v solenoid valve .
    john

    ReplyDelete
  26. good day john, yes you can use it, here's another circuit which you can use:

    https://homemade-circuits.com/2013/10/accurate-infrared-motion-detector-or.html

    it's more accurate than the above

    ReplyDelete
  27. Can we build LED dimmer circuit with this sensor one sensor is used for dimming down and other for up when hand comes to sensor?

    ReplyDelete
  28. yes that may be possible with some thinking

    ReplyDelete
  29. what are the resistive values for the the million ohm variable resistor

    ReplyDelete
  30. sorry I could not get your question...

    ReplyDelete
  31. Teh Yong Kooi, MalaysiaDecember 7, 2017 at 8:08 PM

    Wishing You Mr. SWAGATAM "Good Day"
    Could you enlighten me with similar circuit which works via 5v d.c supply.
    2) the motion sensor could trigger at a . range of about 15 feet.
    3) after 3 or 4 minutes ON then the circuit will on standby mode.
    THANKING YOU VERY MUCH &
    Hope for your kind co-operation.
    Hoping for a detailed d.i.y. circuit.

    ReplyDelete
  32. Thank you Mr. Teh,

    the above circuit will work exactly in the manner that you have mentioned. So you can try the concept and see if it fulfills your requirement.

    Presently I am busy with some other projects, as soon as I finish them I 'll start with the above project and make a working video of it.

    ReplyDelete
  33. Teh Yong Kooi, MalaysiaDecember 8, 2017 at 6:44 PM

    Wishing You very good afternoon Mr.Swagatam
    Thank you very much for quick response to my enquiry on the circuits. I appreciate very much your helpfulness.

    ReplyDelete
  34. It is my pleasure Teh, please keep up the good work!!

    ReplyDelete
  35. Good afternoon Sir,
    I'am looking for a cicuit that will detect a train presence.
    A train is coming onto the hiden station and stop. At the stopping point the machine ''cut'' the IR beam existing between an IR Emeter/Receiver. With the appropriate electronic circuit behind, a relay is activated.
    My problem is that, with the circuit I used, the distance between Emeter and Receiver is too short (only 3 inches). I need to have at least 6 even 7 inches to allow the E and R to be located with an angle from the track to avoid to ''see'' the ''space'' between the wagons (and then switching ON-OFF the relay) as soon the train is going on again.
    I do not know if I my explanation are clear enough.
    Thanks anyway for your answer
    Claude

    ReplyDelete
  36. Hi papaciela, which IR sensor have you used in your circuit? According to me most of them will have similar range capability, at around, at least over a feet, I am not sure why your circuit is not able to function at this range.

    By the way I have a few related posts which you an try

    https://homemade-circuits.com/tuned-infrared-ir-detector-circuit/
    https://homemade-circuits.com/accurate-infrared-motion-detector-or/

    https://www.google.co.in/url?https://homemade-circuits.com/simple-proximity-sensor-circuit/

    ReplyDelete
  37. Hi Swag,
    I received your answer wich was very quick. Thanks a lot.
    The emetter is a SFH 485, the Receiver is a SFH 313 and I used a comparator LM 311. The diagram was ''copied''from this link :

    ho-ptit-train.be/Html/technique(dot)html on the § ''Le cablage 4° partie : D├ętection infrarouge''.

    Sorry, the text is in french, but you will understand easily the scheme. Just click on the photo to open the text.
    The author says that the distance between E & R is, without problem, 30cm. He manage, using 4 IR diodes, to reach 150 cm.
    Why could I not realised the same ??? Is my supply not powerfull enough ?? 12 V-1,2 A max-15w ??

    Thank once more for your help and time spend for answering..

    Claude

    I will look at the systems you mentionned.

    ReplyDelete
  38. Thanks Papacelia,

    I think you should build it again, may be your sensors have some problems, because normally 30cm proximity can be easily detected by any ordinary photodiode based proximity sensor circuit.

    You can try the following concept and check if it works for you or not

    https://homemade-circuits.com/simple-proximity-sensor-circuit/

    soon I may try to post a video for this so that you can understand how practically it is supposed to work

    ReplyDelete
  39. helo SWAGATAM thanks for all your great work. now can I use 12v 1A ac/DC adapter to power the circuit, won't it harm the 555 timer

    ReplyDelete
  40. hello davis, you can use 12 1amp it will not harm the IC

    ReplyDelete
  41. HELLO SWAGATAM, I'M TRYING TO BUILD AN ELECTRONIC LIVE ANIMAL TRAP THAT TRIPS WHEN THE ANIMAL BREAKS AN IR LIGHT BEAM INSTEAD OF A MANUAL TRIP. THE TRAP WILL BE ABOUT 2FT WIDE. CAN YOU DESIGN A CIRCUIT TO DO THIS FOR ME? POWER SUPPLY WILL BE 12V SEALED LEAD ACID BATTERY. THANKS IN ADVANCE FOR YOUR HELP.

    ReplyDelete
  42. Hello King, I don't support animal cruelty so I won't be able to help with this project! sorry about that.

    ReplyDelete
  43. DEAR SWAG, WE ARE NOT DEALING WITH ANIMAL CRUELTY. I'M A SMALL FARMER THAT GROWS A WIDE ASSORTMENT OF FRUITS AND VEGETABLES. I HAVE OPPOSUMS, FOXES, AND RACCOONS EATING MY STRAWBERRIES AND SWEET CORN. ALL I WANT TO DO IS CATCH THESE ANIMALS AND RELOCATE THEM. I RESENT YOUR HASTY JUDGEMENT, THESE ANIMALS DO A TREMENDOUS AMMOUNT OF DAMAGE THAT CUTS INTO MY PROFITS. THANKS FOR NOT HELPING.

    ReplyDelete
  44. Hi sir! dear sir i want to use this proximity circuit for obstacles detection but i want to use TSOP17xx sensor instead of phototransistor or photodiode how can i modify the circuit. kindly sir send me the circuit diagram.

    ReplyDelete
  45. Sheraz, you can replace the lower photo transistor with a TSOP1738 sensor in its standard configuration. Just make sure to do two changes after this.

    use a 7805 in between the 12V relay side supply line, and the IC 555 supply line.

    And adjust the left side IC 555 frequency to around 38kHz

    ReplyDelete
  46. Hi.
    May I have the maximum distance reached of the ir beam emitted by ur circuit.

    ReplyDelete
  47. Using TSOP IR sensor can increase the range upto 20 meters.

    ReplyDelete

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