I designed something similar to this and managed to get it published in a magazine. My idea I thought up was a "Digital Darkness/Light Measurer". It used a light dependent resistor and a 556 silicon chip, amongst other things, to measure the amount of light or darkness in a room on a scale of 0 to 9, on a digital display. It was published in the "Everyday Electronics" edition of April 1983. I was paid £12 for my work.

My Uncle who is a radio mechanic made the same circuit in the 80s. He used a power transistor and cut it on the top to make an LDR and he installed the bulb outside in the street. The bulb would go on when the sun set and provide light to passerby at night time.

Hey guys, great video. Are you able to tell me the resistors I'd need to run this off 4.2V please?

Can we attach it with a mode of smart street light but the is a swetch can we take out the switch and place the sender please tell fasr

Increasing resistance to 2k and exposing LDR to high intensity light worked for me you can also try it Thank you for the help 😊

but how do you remove the flicker that is caused by the threshold between afternoon to enter night and vice versa?

This video was really helpful....my physics project was really appreciated 👍👍

Excelente.. pero tengo una duda que pasa si no utilizo transistor? Funcionaria?

hlw, bro..! i was make this circuit using LM 358 & A 3.7Volt Li-Ion cell, also used a VR 20k.(for dark control) for my 12smd (6530) LED strip. i was also use a Darlington BD039 transistor, at output of lm 358. the circuit well opereted but a problem has found, during at off position, the circuit dissipate battery charge. have you any solution to prevent from this issue ? please reply as soon as possiable.

Can i replace buzzer with dc motor? I want to make something move when the laser is cut.

Yess!! It works perfectly

Is there a common emitter circuit or a common collector circuit in this circuit?

Will it work if use 20k r instead of 50k

Hi I am not an expert in electronics/electricals, I need help on my solar lamp post. During daytime, it automatically switches off. But comes night, it doesn't turn on automatically. It comes with a remote control that I can switch on manually. What could be the problem? Can I rig the remote control and add a photoresistor LDR and put something to press and hold the ON button? Where can I connect the LDR in the circuit of the remote control? What is the specs of the LDR? The remote is powered by just 3v 2x1.5AAA battery.

I am right if I think I need to switch the 100kohm (2 50k’s ) resistors to one 10k resistor if I want to use a 5 Volt source? And can I use other transistors. I have some PNP transistors.

@ProfessorInventor

3 жыл бұрын

I also have made a shadow detector circuit. You can also watch it. kzread.info/dash/bejne/mGWHx9edktabdps.html

Its a great and helpful tutorial, thank you! but what if I want to add 13 more 4.5 lumens of LEDs to the construction to make it brighter? Current limit is 25mA Do you mind helping me how the construction is going to be like? For eg. how many more resistors do I need to add and what are the values for each resistor? Your help and response would be more appreciated!

@ProfessorInventor

3 жыл бұрын

I also have made a shadow detector circuit. You can also watch it. kzread.info/dash/bejne/mGWHx9edktabdps.html

@Pehesara_Gaming

2 жыл бұрын

Make a relay circuit

can it work reversly like it will stay on till is in light and gets of when lights go out

Help ..how can I increase sensitivity of the LDR?

I made the same project but it is not working can you tell the reason i make the same connection

Can u explain its working wt happens

Is it neccesary to have the transistor and resistors? Cant you just use the power, LDR and LED?

Can we use bc548 transistor

Can I use diode in this circuit please tell ?

How to use it with a variable resistor or POT ?

I am planning to make this my first electronics diy project

You are a genious Engineer

its so simple circuit if we connect 100 k resistor with series with ldr it also properly work and if ldr ressitor value in kilo ohm connect mega ohm resistor with ldr it will also work.nice

Can we connect buzer with led

Muchas gracias por tu vídeo, podrías enviar una foto con el circuito en placa por favor?

@ProfessorInventor

3 жыл бұрын

I also have made a shadow detector circuit. You can also watch it. kzread.info/dash/bejne/mGWHx9edktabdps.html

bro , for me always led is in on condition

@ParthPatel-uu9gh

3 жыл бұрын

Same here problem

@zas-fp9gt

3 жыл бұрын

I had the same problem....I figured out that LDRs are not that sensitive in our homes or our daily environment....it should work in direct sunlight or when you throw torchlight on it...Hope it helps 👍

@hariprasadshanmugam9363

3 жыл бұрын

@@ParthPatel-uu9gh change the resistance bro..

@ProfessorInventor

3 жыл бұрын

I also have made a shadow detector circuit. You can also watch it. kzread.info/dash/bejne/mGWHx9edktabdps.html

@mulpurubakthasingh1247

3 жыл бұрын

@@ProfessorInventor THANK U

wow amazing i like the project, but I have tried doing it using 2N2222 transistor but not working

How does these resistors help in this circuit. ?

sir whats the use of the IC you have used i think even a parallel connection would have worked.please clarify

@zafaraj8211

5 жыл бұрын

No IC has been used in this circuit. It is a transistor or LDR.

I want to use 220 V ENERGY BULB AND A DC CURRENT TO POWER IT ON, WHAT DO I NEED TO DO?

Thank you very much

hi thank you for this can you tell me how to get 12v power out from LDR Circuit, not 3v I want to set a siren or alarm for this

@mr.mythoclast4451

4 жыл бұрын

LED+ to >500Ohm Resistor to VCC and LED- to Collector Resistor to VCC and Base LDR to Base and GND

please add a potentio meter to adjust the sensitivity of LDR. your project works only if there is immense dark inside the room what if there is partially dark inside the room.

Can you make it revarce i mean when it is dark the power will go on the led

if I wanted to code this for assembly language, where would the input and output be located in this circuit for me to plug into a microcontroller?

@b.tech-beingtechie8450

4 жыл бұрын

@dari r You could configure any one of the port pin as input port and give the connection from the junction of led and resistors to that input.. Configure another pin as output port and connect it to transistor

Can we use the 100k in place of 50k 2

Will only the exact resistor will work??

Can v do with long bread board

man one full view of the schematic would have been great , some of us dont need to see the wire going inside the breadboard, just a schematic shot for those who can read it and move on

@FlowerRFabulous

5 жыл бұрын

thats literally how i feel! and i dont need the music. i need the explanation behind how everything works!!!!

@unionpacific7

5 жыл бұрын

It is a link on description, click and you can find the schematic.

@mr.mythoclast4451

4 жыл бұрын

LED+ to VCC and LED- to Collector Resistor to VCC and Base LDR to Base and GND

@LorDToxchY

3 жыл бұрын

Selfish

@cardsigner

3 жыл бұрын

Negative. Actual video showing that it works, is in accordance to Galileo Galili's scientific method, proving that it works.

DEAR ... I built the circuit and I checked the output voltage it seems fine but I connect the output of the circuit to Arduino board inorder to run it but it doesn't work ... and I covered the LDR and connect the LDR circuit to Arduino circuit then I take the output voltage and found huge drop in the voltage ... I don't know why... can any body help me to sort it out and to run the Arduino board via photocell circuit ... I used 9v battery.

Can i use any npn transistor

Will it work if I use 5 resistors of 10k ohm on series instead of one 50k ohm resistor ?

@b.tech-beingtechie8450

4 жыл бұрын

@ajit kumar resistor value depends on the resiatance of ldr during dark condition, it need not be 50k always

It isw working!Thank you

@MANIKANTAVINJAMURI

2 жыл бұрын

Hlo is it really working??

will 47kohm resistor work instead of 50kohm resistor

Can we use 100oms resistor

Thanks man it works

help. the base voltage stays at 0.75v, i cant make it change based on voltage of the ldr. how do i remedy this?

@mr.mythoclast4451

4 жыл бұрын

try a higher Resistor-Value from VCC to Base (this is called a Pullup-Resistor)

Can i make it without using that particular board that u have used? Plzz reply

Please give a ac to dc converter circuit with item required with value

Can be use single resistor of 100k

Can I use one more led in series

sir 12 volt pat chla sakte hain our 548 use kar sakte hain batae plz

Can I use pn2222 transistor?

hello, how can I do that the LED is on when light hits the LDR? I want to control a solenoid with it. The solenoid should be activated when light hits the LDR

@joeschmoe3815

4 жыл бұрын

Use a pnp transistor instead of the npn one used here

Bro ithu automatic on off method ah ila intensity control panuma

If we use small buzzer in case of led will it work?

@MrInnovative

6 жыл бұрын

Praveen kumar Das yes it work

@sibijudepr7438

6 жыл бұрын

it will work

I have a question? what is the need of transistor here, as it can be parallel and current can flow in through the sensor during light presence and it can become a high resistor during darkness, this itself will make the current to flow in the parallel path and make the light glow. If possible can you please provide some insight there.

@ProfessorInventor

3 жыл бұрын

I also have made a shadow detector circuit. You can also watch it. kzread.info/dash/bejne/mGWHx9edktabdps.html

It is working...thank you😀

@velusamy1833

5 жыл бұрын

Bro for me working when light is there

@b.tech-beingtechie8450

4 жыл бұрын

@velu samy If u r getting it in opposite conditions interchange the position of ldr and resistors

does this work for LED strips as well?

@mr.mythoclast4451

4 жыл бұрын

sure, you just need a Transistor that can handle the Current. But it would be better to get a Darkness-Sensor with a Schmitd-Trigger

Merci !

please show me the full schematic diagram because i wanted to make robot that will have a sensor like that

Can I use dc motor in place of led

Can we make reverse of this circute that means lighter detecting

@pradiumkumar9060

6 жыл бұрын

YES it can be made

Can we take Resistor of our Choice ?

Creative video, thanks for sharing :)

thank you gb

Thnku so much.

where get the board?\

Sir did we use on this system on 12v battery??? Plsss give me ans fast

@hrideymalhotra6428

5 жыл бұрын

No brother It can cause overload.

Can someone explain what the resistors in series with LDR do and why they're needed? Wouldn't it work without them?

@captwig

3 жыл бұрын

Being the ldr a resistor itself, it will form a voltage divider when associated in series with a resistor. Less ambient light, higher will be the ldr resistance, so current will flow to the transistor.

Sir please reply whether 100K resistor or 150K resistor is required🙏🙏. You using brown, green, yellow gold resistor that is 150k resistor

I have a sensor as showed in your description 105 rs what to do with that

It is the opposite with me. It lights on when the surrounding is bright while it lights off whenever it is dark. What am i supposed to do with this

Can i use bc 547

If I use transistor bipolar 2n2222a it will work?

@zafaraj8211

5 жыл бұрын

2N2222A not tried but I have tried 2N2222, it works nicely, when connected in EBC pinout configuration.

Can i use 10 led?

i tested something this circuit also works with an 2n2222 npn transistor!

How to make same thing for 220v?

It is working I love your chanal

@zafaraj8211

5 жыл бұрын

Yessss!

Very basic very useful

How long will the battery last?

it doesn;t work for me so i need help

it seems there is no base connection so the bc547 not in effect as a tr but jumper so that mean the circuit works w/o tr bc547

what is the name of the bord in which you placed the led ,ldr etc ?

@zafaraj8211

5 жыл бұрын

Bread board

where to buy resistors online? and could you explain the principle use of transistor

thank you

Does ldr work on infrared light,???

@zafaraj8211

5 жыл бұрын

No.

How LDR work s

Can we use Two Led in this circuat

@waseem2645

6 жыл бұрын

yes why not.

sir .. is it posible if i use it as a switch for counter ?

@akshatgarg7763

5 жыл бұрын

Jiar Sebastian yes you can use a switch

It did not work to me. I just notice in the steps that the 1K ohm resistor was first in negative, then later on it was already in positive. please show also your changes next time when making a tutorial.

@mr.mythoclast4451

4 жыл бұрын

Blue 3mm LED BC547C (generic NPN like 2N2222 ...) in my Setup the standby-current is: 220 uA full on: 19,80 mA Put the Resistors from VCC to Base and LDR from Base to GND. You can also use a Potentiometer instead of the fixed Resistor-Value, to get the Spot you want to turn on/off the LED, then read the Potentiometer-Value with a DMM and grab a Resistor that exactly fits your need.

@techdicted

4 жыл бұрын

Yea, it failed o work for me too. But after I figured it out I made this video :- kzread.info/dash/bejne/lXp60qtrfpnYaNI.html . Haha I am certain you already figured it out but hopefully, it may help someone else.

Its very best and easy😀

Can we run motor in place of led

@voizek

4 жыл бұрын

Yes

@abhijithanilkumar4959

3 жыл бұрын

Good idea

Thank you so much

dude did u used it for class 12 physics investigatory project

What will the values of resistors be if I use a 5V supply??

@practicallab

4 жыл бұрын

100 k work on 5 volt