I tried this but when I test with the laser beam on to the LDR it works when you break the beam your one switches the laser off my one stays on it does not break the circuit could it be my switch I think yours is a press button please advise me
Hi, If you need more sensitivity you can replace R2 (1k) resistor with 2k or even 4.7k or higher (but don't make sensitivity very high, because it will start to sense light not only from the laser but also from another light sources). Also, you can try to make the laser beam more thick by adjusting focus (but this may not work, because there may be not enough light for LDR07 so you'll need to change that R2 resistor to make it more sensitive). Alternatively, you can fix the laser pointer first, and only then move LDR07 into the laser beam.
hello , how your " light dependent resistor LDR07" work? is it out put analog signal ? i build something like your but it dont work! i think my problem is the light resistor.
Hello, LDR07 is an analog device. LDR07 just by itself doesn't output anything, It is more accurate to say that LDR07 changes its resistance depending on the amount of light it senses. You can see it yourself, just connect LDR07 to a multimeter and measure its resistance, and you will see how resistance is changing depending on the amount of light. In my circuit, I've used so-called "voltage divider" which consist of 1k resistor and LDR07 (On the circuit it is labelled as "R2" and "LDR1"). The "voltage divider" transforms changes of resistance into changes of voltage. Now if you connect a voltmeter between gate and source leads (labelled as "G" and "S" on the circuit) of the MOSFET Q1 you can see how voltage changes depending on the amount of light. I am not good at explanation, but I hope it is helpful.
would it be fine if I replaced the 2N7000 with a different transistor? if so which one should I use considering that I used all the exact materials listed.
Hi, Yes, the only one I think of is IRL540N, but it is much more powerful MOSFET, and much bigger also. It should work fine without any problem if you connect it correctly.
Sir I have built the same circuit until 3:10 and everything is working fine but the step at 3:11 is not working when I point the laser to ldr and turn it on it doesn't stays on please help sir ( I have used normal LDR which is available in local market)..
Hi, maybe your LDR has different characteristics than mine, I've used LDR07. Anyways, try to replace R2 (1K) resistor with 4.7K or maybe even 10K, it will make this device much more sensitive to light.
sir, i had made this project and it is working great .But , can you give me a circuit diagram other than (00:54) in google or give me a ppt based on this project if you can, it will help me a lot .
Sir, please advise me for : I want to use this laser beam to operate 6 volt relay so as to use as a security purpose for lightning the 40 watts led bulb instead of your small buzer. Is it possible
The easiest way: is to use a LM7805 voltage regulators to power the circuit with 5V and then use a 5V relay to control 12V siren. There is also another (more advanced) way: you will need to replace Q2 MOSFET with much more powerful one, for example, IRF540N, and replace (add) resistors with appropriate values. (I wrote values for 12V somewhere in the comments, but it is untested). and after all of this, you will just need to connect siren instead of the buzzer.
Almost any other N-channel MOSFET transistors should work fine. You can try IRFZ44, IRF540N, IRL540N (but they are much bigger and more expansive, I don't know a good replacement for 2N7000, sorry). With other MOSFETs some minor adjustments may be needed... maybe you will need to replace resistor R2 with 2K... Also, you may need to connect a resistor in parallel to the laser (just connect any 10k - 100k resistor). If you find IRL540N, then no changes to the circuit will be needed. (IRF540N and IRL540N are different transistors).
Hey man great video but my model seems to be having a problem. I have done everything accordong to the circuit except that since i couldnt find 2n7000 mosfet i used an IRFZ44N mosfet . From a previous comment i modified the circuit by adding a 51k resistor parallel to the LDR and added a 2.7 k ohm instead of the 1 k ohm resisitor. But the laser does not stay on but turns off when i stop pressing the button and after that the buzzer and light turn on on themselves . Please help me if you can . Thank you
Hi, probably to late to answer. I think you don't need adding a 51k resistor parallel to the LDR (don't know what comment you referring to). Maybe 2.7 k ohm is not enough, try more, for example, 10k, or 45k. And point the laser precisely at LDR. IRFZ44N and 2n7000 have different spect, so could be some issues.
Hi, I think you can find better circuit solution if you need to make it separate. Here is why: The main idea of my laser alarm is that when you break the laser beam, it triggers the buzzer, and the laser turns off. If you use a separate laser it will not be turned off, which means that at first (when you break the laser beam) it will make noise, but the device will stop making noise as soon as it starts seeing the laser beam again.
Hi, The yellow wire connected to the plus of the laser pointer, and the blue wire connected to the minus of the laser pointer. The aluminium housing (body) in that laser pointer is a big plus terminal, so I connected a plus (yellow) wire directly to it. (I think that in the different laser pointers you may need to connect wires differently, so look at the circuit diagram on 0:54 to get the idea how to connect)
I still recommend you to find some n-channel MOSFETs. BC547 is not MOSFET, so you can't just replace 2N7000 with BC547. Though it is possible to use BC547, but you will need to use more additional components (more resistors) and the most important, you need to find correct values for those resistors. I've chosen to use MOSFETs because this circuit is much simpler with them.
If I really wanted to make it work with BC547 I would do something like this: drive.google.com/open?id=1RAfSqoimKu14_n1HmBkRxvimMKvPLmf- It is untested, it is just my thoughts, maybe you will need to replace 1K with something bigger like 10k or 50k.
Really good project. If I don't want to turn off laser pointer with the reset button but only want to turn the buzzer off (and LED) with reset button, can I just solder the reset button else where in the circuit? I think maybe on both sides of the buzzer so the LED and buzzer will be off with the reset. Maybe it's more complicated but your help will be appreciated
Hi, The problem here that it is working (and designed to work) all together, and when the laser is on then the LED with the buzzer is always off and vice versa. It was made intentionally to have that triggering effect. If the laser always stays on then if someone blocks the laser beam then the buzzer will make noise, but as soon as LDR will start seeing the laser beam again it will stop making noise automatically without any reset. In other words, It will just detect the light from laser without any triggering, and you will not need the reset button at all. If it is what you what then I can tell you how to modify the circuit. (You can't just reset the buzzer without resetting the laser, they rely on each other, and to do that you will need a much more complicated circuit.)
Thanks for your answer. So if I want to have an unstop laser beam, sould I use the circuit you show in the video "How to set a security alarm device with a reset button" and use a light dependant resistor instead of a reed switch and use a standalone laser beam?
No, unfortunately. You can't just replace 2N7000 with BC547, for this project you need to use MOSFET transistors only. Theoretically, it can work with BC547 but we'll need to redesign the circuit completely.
Hi, Just use LM7805, it will make 5V from 12V. Somewhere in the comments I also described another way how to do it, which require changing and adding resistors, but I recommend just to use LM7805 because it is the easiest way. (The laser in this video works with 5V, not 4V)
I don't completely understand what problem you are facing. After pressing the button your buzzer should turns off and the laser should turns on, it is ok. And then when you still pressing the button you need to point the laser at LDR07, then you can release the button and the buzzer should stay off. Watch the video at 4:45
You can use a relay in such circuit for tripwiring. I have made a tripwire alarm by only using transistor,relay,ldr,laser, battery and one buzzer.That circuit is superior to this one.
The laser should be off by default and should turn on when you press the button. I think that Q1 MOSFET is dead. Let's do a test just to be sure that Q1 is dead. To do a test just disconnect LDR07 and the button, if after the disconnection the laser still stays on it means that Q1 MOSFET is dead, and you need to replace it with a new one. P.S. Be careful with static electricity while soldering, maybe you killed your 2N7000 MOSFET with static electricity somehow, or maybe it was dead even before you bought it... I don't know... I almost sure that Q1 is dead, but do a test to be completely sure.
Hello Sir I MAKE THIS CIRCUIT . PRESSING THE BUTTON LASER LIGHT IS ON STAY LDR BUT PRESSING THE BUTTON BUZZER IS RINNIG CONTINUES. THE BUZZER IS NOT CLOSED AFTER PRESSING THE BUTTON SIR ,PLEASE REPAY
Hi, You need to change values of the resistors. R2 Should be 470 Ohms instead of 1k. Resistor R3 I think is better to replace with 1k instead of 470 Ohms. But the most important is resistor R1 which is inside the laser pointer, it should be 400 Ohms instead of 100 Ohms. I think it will be easier just to add an additional 300 Ohms resistor sequentially to the wires that go to the laser pointer, 300 Ohms and 100 Ohms together will be 400 Ohms.
![Electrical Projects [CreativeLab]](http://yt3.ggpht.com/ytc/AIdro_nXuaCebPi8RjzINYxrETo1-K9WQerCEIndpQMoSs0BfQ=s48-c-k-c0x00ffffff-no-rj)
it work perfectly.thanks
Can I use Bc547 transister
Very Interesting. Might use this. Thanks
I tried this but when I test with the laser beam on to the LDR it works when you break the beam your one switches the laser off my one stays on it does not break the circuit could it be my switch I think yours is a press button please advise me
more than 1 year ago still no reply why ???????
Can you use a BC557 or BC547 instead of 2N7000?
Please give me any idea or option to make the surface of ldr big and more sensitive. It takes too much time to adjust the laser on the ldr.
Hi, If you need more sensitivity you can replace R2 (1k) resistor with 2k or even 4.7k or higher (but don't make sensitivity very high, because it will start to sense light not only from the laser but also from another light sources). Also, you can try to make the laser beam more thick by adjusting focus (but this may not work, because there may be not enough light for LDR07 so you'll need to change that R2 resistor to make it more sensitive). Alternatively, you can fix the laser pointer first, and only then move LDR07 into the laser beam.
I did it but its not working and the reset button is not working
hello , how your " light dependent resistor LDR07" work? is it out put analog signal ?
i build something like your but it dont work! i think my problem is the light resistor.
Hello, LDR07 is an analog device. LDR07 just by itself doesn't output anything, It is more accurate to say that LDR07 changes its resistance depending on the amount of light it senses. You can see it yourself, just connect LDR07 to a multimeter and measure its resistance, and you will see how resistance is changing depending on the amount of light.
In my circuit, I've used so-called "voltage divider" which consist of 1k resistor and LDR07 (On the circuit it is labelled as "R2" and "LDR1"). The "voltage divider" transforms changes of resistance into changes of voltage. Now if you connect a voltmeter between gate and source leads (labelled as "G" and "S" on the circuit) of the MOSFET Q1 you can see how voltage changes depending on the amount of light. I am not good at explanation, but I hope it is helpful.
thanks for your reply. i will keep going!!
i watch one of your video tutorial . then DONE!!
would a 2N3904 TRNANSETER WORK
I also am having trouble the indicator light stays on also the lazer but nothing happens when 8 break the light connection to the sensor . Any ideas??
do you sell these online?. it would be easier for me to buy this from you..
would it be fine if I replaced the 2N7000 with a different transistor? if so which one should I use considering that I used all the exact materials listed.
Hi, Yes, the only one I think of is IRL540N, but it is much more powerful MOSFET, and much bigger also. It should work fine without any problem if you connect it correctly.
Awesome 👌
Sir I have built the same circuit until 3:10 and everything is working fine but the step at 3:11 is not working when I point the laser to ldr and turn it on it doesn't stays on please help sir ( I have used normal LDR which is available in local market)..
Hi, maybe your LDR has different characteristics than mine, I've used LDR07. Anyways, try to replace R2 (1K) resistor with 4.7K or maybe even 10K, it will make this device much more sensitive to light.
Electrical Projects [Creative Lab] ok sir I will try and thanks for reply...
100k is okay?
It is really amazing I love that sir. I wanna ask you some thing si ok with that
We can use bc547 transistor please send video
sir, i had made this project and it is working great .But , can you give me a circuit diagram other than (00:54) in google or give me a ppt based on this project if you can, it will help me a lot .
Sir, please advise me for : I want to use this laser beam to operate 6 volt relay so as to use as a security purpose for lightning the 40 watts led bulb instead of your small buzer. Is it possible
Hi, Yes. Just connect the coil of your relay in parallel or instead of the buzzer, and then you can control any bulb or LED.
can i use 4.5v power supply
What i have to do if i want to my buzzer work on 12v becouse i have a siren that must work on 12v?
The easiest way: is to use a LM7805 voltage regulators to power the circuit with 5V and then use a 5V relay to control 12V siren.
There is also another (more advanced) way: you will need to replace Q2 MOSFET with much more powerful one, for example, IRF540N, and replace (add) resistors with appropriate values. (I wrote values for 12V somewhere in the comments, but it is untested). and after all of this, you will just need to connect siren instead of the buzzer.
sir please tell me the different transistor names used instead of 2n7000
no 2n7000 transistor available at our place
Almost any other N-channel MOSFET transistors should work fine.
You can try IRFZ44, IRF540N, IRL540N (but they are much bigger and more expansive, I don't know a good replacement for 2N7000, sorry).
With other MOSFETs some minor adjustments may be needed... maybe you will need to replace resistor R2 with 2K...
Also, you may need to connect a resistor in parallel to the laser (just connect any 10k - 100k resistor).
If you find IRL540N, then no changes to the circuit will be needed. (IRF540N and IRL540N are different transistors).
Hey man great video but my model seems to be having a problem. I have done everything accordong to the circuit except that since i couldnt find 2n7000 mosfet i used an IRFZ44N mosfet . From a previous comment i modified the circuit by adding a 51k resistor parallel to the LDR and added a 2.7 k ohm instead of the 1 k ohm resisitor. But the laser does not stay on but turns off when i stop pressing the button and after that the buzzer and light turn on on themselves . Please help me if you can . Thank you
Hi, probably to late to answer. I think you don't need adding a 51k resistor parallel to the LDR (don't know what comment you referring to). Maybe 2.7 k ohm is not enough, try more, for example, 10k, or 45k. And point the laser precisely at LDR. IRFZ44N and 2n7000 have different spect, so could be some issues.
@@ElectricalPro Thanks for the reply i will try it.😄😁
Great video, but can I run the laser and the circuit from different power supplies, I want to put the laser on the other side of a room, thank you
Hi, I think you can find better circuit solution if you need to make it separate. Here is why: The main idea of my laser alarm is that when you break the laser beam, it triggers the buzzer, and the laser turns off. If you use a separate laser it will not be turned off, which means that at first (when you break the laser beam) it will make noise, but the device will stop making noise as soon as it starts seeing the laser beam again.
It would be great if you can give me a different circuit solution
Does the circuit components get damaged if 9v battery is used??
It can damage the laser
I didn't understand where you attached the second wire at 1.16seconds
Hi, The yellow wire connected to the plus of the laser pointer, and the blue wire connected to the minus of the laser pointer. The aluminium housing (body) in that laser pointer is a big plus terminal, so I connected a plus (yellow) wire directly to it.
(I think that in the different laser pointers you may need to connect wires differently, so look at the circuit diagram on 0:54 to get the idea how to connect)
Electrical Projects [Creative Lab] so nice of you to reply so clearly thanx
Can I use in stand of 2n7000 transistor any other transistor
You can use BS170 instead, but BS170 has a different pinout.
Electrical Projects [Creative Lab] any other like BC547 because I cont get that component sorry any other plz
I still recommend you to find some n-channel MOSFETs. BC547 is not MOSFET, so you can't just replace 2N7000 with BC547. Though it is possible to use BC547, but you will need to use more additional components (more resistors) and the most important, you need to find correct values for those resistors.
I've chosen to use MOSFETs because this circuit is much simpler with them.
If I really wanted to make it work with BC547 I would do something like this: drive.google.com/open?id=1RAfSqoimKu14_n1HmBkRxvimMKvPLmf- It is untested, it is just my thoughts, maybe you will need to replace 1K with something bigger like 10k or 50k.
Really good project. If I don't want to turn off laser pointer with the reset button but only want to turn the buzzer off (and LED) with reset button, can I just solder the reset button else where in the circuit? I think maybe on both sides of the buzzer so the LED and buzzer will be off with the reset. Maybe it's more complicated but your help will be appreciated
Hi, The problem here that it is working (and designed to work) all together, and when the laser is on then the LED with the buzzer is always off and vice versa. It was made intentionally to have that triggering effect. If the laser always stays on then if someone blocks the laser beam then the buzzer will make noise, but as soon as LDR will start seeing the laser beam again it will stop making noise automatically without any reset. In other words, It will just detect the light from laser without any triggering, and you will not need the reset button at all. If it is what you what then I can tell you how to modify the circuit.
(You can't just reset the buzzer without resetting the laser, they rely on each other, and to do that you will need a much more complicated circuit.)
Thanks for your answer. So if I want to have an unstop laser beam, sould I use the circuit you show in the video "How to set a security alarm device with a reset button" and use a light dependant resistor instead of a reed switch and use a standalone laser beam?
Yes, it should work, but I personally did not test that circuit with a laser and LDR.
sir where you get these Things
its good...but i need dc 12or 24v even ac 220 v
Can I use other transistor like bc 547
No, unfortunately. You can't just replace 2N7000 with BC547, for this project you need to use MOSFET transistors only.
Theoretically, it can work with BC547 but we'll need to redesign the circuit completely.
@@ElectricalPro Why is there a need to redesign the circuit? Both of these transistors work almost the same
Hi please tell me how to make the circuit by using 12v DC
while the laser is only 4v capacity
tell me the circuit please
Hi, Just use LM7805, it will make 5V from 12V. Somewhere in the comments I also described another way how to do it, which require changing and adding resistors, but I recommend just to use LM7805 because it is the easiest way.
(The laser in this video works with 5V, not 4V)
Sir, I tried your method, but when I turn the laser another time the buzzer turn off. where is the problem ?
I don't completely understand what problem you are facing. After pressing the button your buzzer should turns off and the laser should turns on, it is ok. And then when you still pressing the button you need to point the laser at LDR07, then you can release the button and the buzzer should stay off. Watch the video at 4:45
Thank you for your reply
it's good, it was a problem connecting the wires
thank you very much = Merci beaucoup
How to explain this projects please give the
sir,will you tell it's working.
please help me sir
Sir... I want to make this circuit with 12v Siren. Pls give circuit diagram
Cool !!
How to make that can you please slowly
how to use relay.??
please answer.!!
What do you mean? Do you mean how to use relays instead of MOSFET transistors? if so, then I think it is impossible.
You can use a relay in such circuit for tripwiring. I have made a tripwire alarm by only using transistor,relay,ldr,laser, battery and one buzzer.That circuit is superior to this one.
This project total cost?
Is this is working ?
I used all the components as said in the video
the light continuously on ante reset button is also not working
The laser on ? or the LED with the buzzer on?
laser light is on and the it is not breaking while keeping the hand in between
The laser should be off by default and should turn on when you press the button. I think that Q1 MOSFET is dead. Let's do a test just to be sure that Q1 is dead. To do a test just disconnect LDR07 and the button, if after the disconnection the laser still stays on it means that Q1 MOSFET is dead, and you need to replace it with a new one.
P.S. Be careful with static electricity while soldering, maybe you killed your 2N7000 MOSFET with static electricity somehow, or maybe it was dead even before you bought it... I don't know... I almost sure that Q1 is dead, but do a test to be completely sure.
Mast h sir or banao
Hi sir can you give me the circuit diagram of that circuit?thank you so much
Hi, it is at 0:54
Hello Sir
I MAKE THIS CIRCUIT . PRESSING THE BUTTON LASER LIGHT IS ON STAY LDR
BUT PRESSING THE BUTTON BUZZER IS RINNIG CONTINUES.
THE BUZZER IS NOT CLOSED AFTER PRESSING THE BUTTON
SIR ,PLEASE REPAY
Hello, it seems that your Q2 MOSFET is dead, try to replace Q2 with a new one.
Hello Sir Thanks For Giving feedback IS Working Properly
How to make this circuit with 12 volt battery
Hi, You need to change values of the resistors.
R2 Should be 470 Ohms instead of 1k. Resistor R3 I think is better to replace with 1k instead of 470 Ohms.
But the most important is resistor R1 which is inside the laser pointer, it should be 400 Ohms instead of 100 Ohms.
I think it will be easier just to add an additional 300 Ohms resistor sequentially to the wires that go to the laser pointer, 300 Ohms and 100 Ohms together will be 400 Ohms.
Use lm7805 to get 5v from 12v
Hi I was make this system but it works only first time and again it's not working plz send me solution
HI, you probably need to point the laser at the LDR very precisely. What do you mean by "it works only first time"? describe it more.
Hello Sir
How can I made this project with a 9V battery.
Yes, just add LM7805 voltage regulator, and you will be able to use any DC power sources from 7 to 35 volts.
(it is the simplest solution).
Sir can u please send me circuit design on my gmail account my account is singhsikarwaryash@gmail.com
@@ElectricalPro 9V instead of 5V is fine..no need for LM7805
We also use 5.7 charger
Please do it in very slow method
Super
Can you make this video in hindi & slowly
PLEASE SEND ME WORKING PRINCIPLE OF THIS CIRCUT
Cool
The burglar will trip over the wires and become tangled up in the wires. Needs to be wireless in real world application
Sir please make this video again its to fast and explain it clearly
Laser cross alarm
Plzz redesign it for me I can't find MOSFET transter plzzz sir I am your subscriber plzz do it for me or call subscriber
hi
no