How to make a Laser Alarm with a 741 op amp and a 4017 timer

[p264pandya]

I also want to make a similar kind of system but the difference is that i want to start the buzzer when the laser strikes the sensor. I am a beginner and has no knowledge of circuits so can you please help me and mail me the circuit diagram and the list of things i should use?? My mail Id is p264_pandya@yahoo.com

[TheBatusaypogi]

can you tell what are components of your laser alarm, i have a project about security system

thanks in advance:-)

[dbabic70]

I only have in my shema diode, tranzistor,resistor ,kondenzator 1000 piko farad battery and buzzer from a wireless doorbel .whole sistem with buzzer. could you tell me where do i found these your extra parts in what home elements. i am sorry i write not very good.but speak and read everything.

[dbabic70]

hey i found somewhere similar thing but the buzzer make noise only when i break the beam.so i am beginer and i like your videos. i don't know some parts.i would like to send you an email or you could send to me so i can explain what is my problem. I am gago. Thanx. My email is dbabic70@gmail.com

[tradecycles]

what is ldr? always write a description

[Flea5000000000]

@tradecycles an LDR is a light dependent resistor that changes it's electrical resistance depending on how light or dark it is. The more light less resistance.

[Flea5000000000]

@tradecycles there is no need for a decription because if you are building this it is assumed that you know what the compents are, if you don't just post a comment.

[Advantage12]

Thanks for the video I just built this myself it works great thanks! Also pin 6 and 7 on the 741 look good to me... Mine wouldn't stop going off until I switched them back to the way you had them in the schematic you posted. Anyways thanks again!

[ChristianVdC]

schematik please

[ramicaza]

why so complicated? just use a scr lol i have a tutorial on my channel for my version. Ur a genius btw

[Flea5000000000]

@ramicaza thanks :D



[Flea5000000000]

@thunda828 sorry I'v been busy but I will put a tutorial on it

[joemnice]

hi!, can anyone post some link or send me the clear version of this schematic diagram of this. i cant really see it.... thumbs up so everyone will be informed..

[bugdann]

I have built everything as your scheme, but its not working something. The timer becomes very hot after few seconds and the buzzer runs continuously without any changes. Do you have an Idea what happened? Or, I need to build it again, maybe I have wrong with something.. Thanks !

[Flea5000000000]

@bugdann It sound like you may have too mutch current running through the ic, try building it again, but be carefull you may burn out the ic.

[adikakazizou]

@Flea5000000000 thnx video really helped me out in my project btw can it be made without 4017 i.e usin only 741 as comparator 4017 is needed only 4 reset purpose right does it have ne other use?????????? pls reply soon

[Flea5000000000]

@adikakazizou you do not have to use the 4017, as you said it is just for the reset

[adikakazizou]

@Flea5000000000 thnx video really helped me out in my project btw can it be made without 4017 i.e usin only 741 as comparator 4017 is needed only 4 reset purpose right does it have ne other use?????????? pls reply soon

[ficho9999]

Hi, again me! You didn't write what is the name of transistor you use in project! So, please tell me! Tnx!

[Flea5000000000]

@ficho9999 The transistor is not important in this circuit! it just boosts the power to the beeper. You can use a buzzer on the output and no transistor. No I do not know what type it is because it does not matter, as long as it lets power through when there is 5vs to the base.

[ficho9999]

Hi! I like ynur project. Can you please send me the shematic, and the list of components.

e-mail: filip.g@vip.hr

thanks!

[Flea5000000000]

@ficho9999 dude! the schemattic is in the vid and the components I explane, THAT IS THE ENTIRE REASON I DO THAT, SO YOU DON'T HAVE TO ASK FOR THE SCHMATIC OR COMPONENTS!!!!!!!!!!!!!!!!!!!

[ejatlah]

is it 547 transistor?

[Flea5000000000]

@ejatlah Hey, IT DOES NOT MATTER WHAT TRANSISTOR IT IS, AS LONG AS IT LETS POWER THROUGH WHEN THE BASE IS ABOVE +3V... (That was not suppost to be in caps)

[ejatlah]

@Flea5000000000 THANK YOU (that was not suppost to be in caps ;p)

[Flea5000000000]

@ejatlah XD

[ejatlah]

anyone know what type of transistor in this video.please help me

[bellerve201]

1. What type of transistor?

Thanks!

[Flea5000000000]

@bellerve201 sorry I don't know but you don't need the trasistor it just boosts power to the buzzer

[Flea5000000000]

@besanher I'm makein a video that shows you how to put it all together.

[michal3ek]

now? /img32.imageshack.us/i/zdjp.pn­g/

[Flea5000000000]

@michal3ek nope.... try to just put the url from the adress bar.

[michal3ek]

here?? /img526.imageshack.us/i/beztyt­uuqry.png/

[Flea5000000000]

@michal3ek the link didn't work....

[michal3ek]

ok i try this and i'll write if it help.

[michal3ek]

so i've done it and it's not working:( this is my schematic: i m g 8 2 1 . i m a g e s h a c k . u s / i / l a s e r j . p n g / (write without space) what do i wrong? i used 2sc945 transistor and 12v buzzer.

[Flea5000000000]

@michal3ek

Hey, have you tested your transistor by connecting the bace to the 9v rail and it should make the buzzer buzz.

[Flea5000000000]

@michal3ek

The LDR may be your problem as the 741ic is comparing the input of the LDR and the resistors. When the LDR's output gos under the resistance level the ic outputs HIGH (9V).

To try and fix this (if it is the problem) then try putting a 10k potentiometer in place of the 10k going from the two 360 ohm resistors to pin 3 on the 741 ic.

Then test different resistance levels with the potentiometer.

Hoped this helped.

[michal3ek]

hi Flea5000000000 could you send me the shematic to: michal_p-16@wp.pl ,and write what is the name of transistor and tell me: can i use potentiometer here? and draw schematic with potentiometer please:)

[Flea5000000000]

@michal3ek The schmatic that I would send you would be the same in the video...

The transistor I do not know the name but as long as it will let current through when the base has a voltage of over 1v its fine.

Yes you could use a potentiometer in place of the 10k going from the two 360 ohm resistors to pin 3 on the 741 ic.

[mohits9]

thankyou very much...

[mohits9]

@Flea5000000000

thnx for quick reply...

i wil ask again if any problem comes...

[mohits9]

@Flea5000000000

thnx for quick reply...

i wil ask again if any problem comes...

[Flea5000000000]

@mohits9 ok

[mohits9]

can anyone tell me that what happening in the circuit?? I want the explanation of circuit.

[Flea5000000000]

@mohits9 hey, first the 741ic is comparing the input of the LDR and the resistors. When the LDR's output gos under the resistance level the 741ic outputs HIGH, wich makes the 4017 switch to output pin 1 so it is no longer supplying power to the LDR. Then when you press the reset button it switches the 4017 output to pin 0, wich resets the process (requiring that the LDR has the lazer on it at the moment of reset).

Hoped this helped.

[mohits9]

@Flea5000000000

thanx for quick reply...

i will ask u again if any problem comes...

[mohits9]

@Flea5000000000

thnx for quick reply...

i wil ask again if any problem comes...

[mohits9]

@Flea5000000000

thankyou very much....

[reviathon360]

instead of a 4017 you cout use a 4013 or two nor gates to make a SR latch.

[Flea5000000000]

@reviathon360 errmm I don't know. I don't have any experiance working with the 4013... sorry

[Frawtan]

By the way Flea500000000 I used 2N3904 transistor..is that would be fine?..

What transistor did you use with that project?..=)

[Flea5000000000]

@Frawtan lol im not sure but as long as it lets the power through when the alarm gos its fine

[Frawtan]

Hello Flea500000000!...Nice project you have!.. I've tried building the circuit you have shown and it was successful!.. but i have a small problem regarding with siren there is a little sound coming from it even the laser is shining on the photoresistor although it function normally once the beam is broken it produces a loud sound..

Will you please help me to solve the problem?...=( 

Thanks in advance...Hoping for your reply...

[Flea5000000000]

@Frawtan you can fix the little sound when the alrm is not on by puting a low ohm resistor infront of the beeper that how I fixed it... :) bye

[Frawtan]

@Flea5000000000 Hello!..I just wanna ask if that's normal with the circuit to produce that little sound coming from the buzzer?...Did you also experience the same problem while building the circuit?..

[Flea5000000000]

@Frawtan yes thats normal it happened to me while I was building the circuit

[Frawtan]

@Flea5000000000 i tried this idea but it changes the quality of sound that the buzzer produces as the beam is broken..=(

[Flea5000000000]

@Frawtan humm... try puting a resistor on the positive power rail fom the battery see if that changes the buzzer (basicly changing the 9v to a lower power by puttting a resistor on it). if it doesen't work tell me and ill work on it |:

[ejatlah]

@Frawtan what transistor did you use?

[Frawtan]

Thumbs up sir!..=)

Nice job!..

[Frawtan]

Nice Job!...Thumbs up!..=)

[composerforfilm]

Please send schematic

[Flea5000000000]

@composerforfilm If you can't see the ones in the vid then how are you going to see them better if I send you them?!?!

[composerforfilm]

Can't see. I meant!!!!

[composerforfilm]

Can you please email schematics to Steve@principatomusiccom. I can see them well enough in video. Thanks. Steve

[Flea5000000000]

@composerforfilm The pictures in the video are what I will send you.....

[Flea5000000000]

@composerforfilm and they are verry clear.

[Legolas11007]

is it the 10k resistor that is attached to the non inverting input or the 2 330ohm resistors attached to the 10k resistor I have to change? And would you put in a bigger or smaller resistor?

[Flea5000000000]

@Legolas11007 The 10k resistor which is attached to the 330ohm(change the 10k not the 330). Experiment with the resistance, remember that the 741ic is comparing the - and +. So if - is bigger than + the output is high. The LDR is connected to - so when it is higher than + the output is high. The LDR is high when the lazer is on it.

[Legolas11007]

@Flea5000000000 Cant you jst replace the 10k resistor attached to the + with a potentiometer?

[Flea5000000000]

@Legolas11007 good idea ya that could work

[Legolas11007]

does anyone have an idea which specification the LDR has? I complete circuit is working its just when the laser shines on the LDR the alarm does not turn of completely, its still sightly audible. HELP!!!!!

[Flea5000000000]

@Legolas11007 this may be due to low power or the LDR but you can adust the senceativity by changing the resistors on the 741.

[Flea5000000000]

@Legolas11007 you can fix the little sound when the alrm is not on by puting a low ohm resistor infront of the beeper that how I fixed it... :) bye

[Legolas11007]

@Flea5000000000 Idea sounds good. Do I put the resistor between the 0 Volt rail and the alarm or between the alarm and the emitter of the transistor? And what sort of resistor will I be looking for? 20 ohm, 30ohm?

[Frawtan]

@Legolas11007 yah right we have the same problem Legolas11007!..

let us just try what our master said..=)

I hope it will work...

[kumon21]

Hey thanks for your reply, just a question, why is the pin 4 on he 4017 IC connected so strangely. And I tried to connect it up but the buzzer just goes and the laser does not stop it. Could you please help and I will surely ask you some more questions later on. Is that alright with you ???

[Flea5000000000]

@kumon21 pin 4 is connected to the reset so when the lazer is blocked a pulse is sent to the 4017ic and the output is changed to nuber 1 and then it continues to beep utill you reset the chip to 0 by pressing reset on the button.

[kumon21]

Hi there Flea, I tried making this circuit from your schematic but i couldnt get it to work. Could you make a step by step video or pics to show how you connected the components. Also could you please re-check your schematic as i think there might be a few errors. i.e. the clock input on 4017 (pin 14) is connected directly to the output of buzzer/transistor. But main point is the step by step expanation video as I think most of us are waiting to make one of your project ourselfs.

[Flea5000000000]

@kumon21 no that wire is correct as it is the input line for the 4017 and the input line for the buzzer

[Flea5000000000]

@kumon21 and sorry I can't do a vid right now because my camra broke and I have to wate for it to be fixed

[Flea5000000000]

@kumon21 try changing the LDR as the 741 compares the resistors and the LDR output so when the LDR has a lower power output then the resistors the buzzer is ativated.

[kumon21]

Hi there flea5000, I tried making the project from your schematic but i couldnt get it to work. Could you please make up a step by step video or pics to how did you join up the components. Thanks. Oh and also why did you connect the clock input on 4017 decade counter (Pin 14) directly to the output of the buzzer ???

[edoxs]

hey flea, this is nice, just found it, and im so excited to do it myself, i already read that transistor is just to boost beeper, still i will try diffrent kinds to see which one fits, heres the problem, im at work right now and cant wait to get home to start, but here we are not allowed to have speakers on our computers so i couldnt hear whats the 10k resistor for....

[Flea5000000000]

@edoxs the one on the 4017? If so then that uses the current witch is outputed by the 4017 so it dosen't flick though to the next pin. ok

[TheLastGambino]

hey mate where's that laser alarm redo?

[Flea5000000000]

Sorry, my camra is brocken. It will probaly be fixed with in the next two weeks.

D:

[Legolas11007]

At how much Voltage does your Piezo buzzer operate?

[Flea5000000000]

@Legolas11007 5v but its being supplyed 9v

[TheLastGambino]

great laser alarm mate. I tried to build it using ur schematic but i couldnt get it to work. your video was a bit blurry so i couldnt see the actual components and wires on your board. Can u make a simple step by step video showing what wires go to what and how to have the resistors connected? i would greatly appreciate the help. if u can focus a lil more clearer on the board i might be able to understand how you wired it all up. you definitely did a great job. can u label the pins on transistor

[Flea5000000000]

@TheLastGambino ok and ya sorry it was out of focus.....

[Flea5000000000]

@TheLastGambino ill put it up in around in this week

[Legolas11007]

Is the switch u used a push-to-make or a push-to-brake switch?

[Flea5000000000]

@Legolas11007 push-to-make

[Legolas11007]

and of the transisor aswell please, thank you

[Legolas11007]

Hi Flea,

can you give me the specs on the LDR you used in your circuit cos I really like this system and want to build it myself

[Flea5000000000]

you don't need the transistor it just gives the buzzer more power and the LDR I do not know what type it is but all it has to be is when the lazer is shining on it then the resistance must be zero in the LDR.

[Legolas11007]

Does the LDR has to become absolute zero or can it have like 50-60 ohms still remaining? And is there any way you could find out which transistor u used and maybe give me the partnummber?

[Flea5000000000]

The LDR can be under 1k remaining and you don't need the transistor it just puts some more power to the buzzer/beeper

[felzinhu3]

hi, flea5000......

what the transistor did you use?

[Flea5000000000]

hi, well it dosen't rearly matter you can connect it straight to the 741 op omp output, all the transistor dose is put more power to the beeper to make it louder

[cristoretornebiblia]

I have a breadboard its just a rectangle with no colours on it it goes from A-E then a gap running down and its F-J with rows going down 1-64

How can I do this laser alarm and what resistors did you use? Thanks

[Flea5000000000]

:D :D

[AngelicAnimeX]

nice!! I like the reset as well. Everything is so well done ^_^

[Flea5000000000]

thanks

[engwalidfouad]

@Flea5000000000

Could you send the schema to me? please!!!

eng.walidfouad@yahoo.com

[Afrotechmods]

Well done! I like how it has reset functionality.

[Flea5000000000]

:D please comment