Electronic Circuit: Dark Activated LED light with photoresistor 

I searched a dozen places before I find this channel who actually explained it. A+

Thank you, it worked! I had a yard decoration running on AA batteries that had to be turned on and off. So i hooked this up for it to come on automatically when sun goes down.

Thanks a lot!!!! I had a lot of trouble with all the connections. But after watching this video, I could make the circuit and now my project is actually working. Thanks for your help! :)

thank you for explaining so clearly how the components work to achieve the desired result.

I'm only just getting into this stuff and this video is very helpful! Thank you so much for taking the time to make it! :)

I am always watching your nice vídeos, please keep making them... Have a good vacation!

I really Enjoyed your video my self ! Been looking for video's for My grand-son to watch on electronics circuits trying to get him interested thanks.

Your 4 min video is better then 2 hour of my campus lecturer, super clear explanation

Thank you so much. Your explanation, Diagram and video is very accurate and working. Thank you.

CONGRATS finally I understand this circuit you taught a Brick something you are a very good Teacher Thx, Ed

I like the way you explain how the electronic works .

Helpful and well explained- thank you.

Thank you for the tutorial, it was very useful for me

Thanks, it is great example, simple to understand, please keep creating new videos... :)

Thank you, Learned so much

Hi there, I’m building a bike light. I managed to flatten out the inductance spikes with a continuous light. In addition I was thinking of a much bigger capacitor of around .22-1F added to that the bike light should only consume energy in the eve. Do you think this setup would allow to store the energy in the capacitor? Do you think it would be wise to add a voltage drop lockout? My main concern is that the extra resistors would take the energy that would otherwise be going to the led.

Great Video! Keep posting more videos please.

Thanks Sir! You saved my day!

Super helpful, thank you!

Another great tutorial! Cheers

Great tutorial I had tried several other web based tutorials but your's seemed to be the one that worked for me, got the project up and running in no time. Can you please demonstrate how to add addition LEDs in either series or parallel?Thanks

These videos are really helpful and nice small projects to explore the world of electronics.

Thank you so much for this wonderful video. I understand the electronic circuit now so much better! :-) can you tell me which program you use to draw the circuit on the computer? Thanks in advance and good luck with everything.

Only that worked so far thanks!

That's loved this video got it straight away thanks

Danke die Skizze mit den Pfeilen erklären das super. Kein anderes Video bei RU-vid erklärt es besser.^^

Great Lesson. Thans ! Like !

thank you, wonderful explanation

This was really helped me out

Hi. Why did you place the load on the transistor's emitter? It is my understanding that when using a NPN transistor (per the diagram), the load should be placed at the collector. Thanks!

Thank you!

can i use more than 1 led and what resistor would i need if i use 9v battery?

Awesome videos!!!

Thank you for this! It showed me the mistake in my first circuit!

Could capacitors be used before the LED to exaggerate the dimming effect?

What do I need to add or change to make this work with two LEDs?

Thanks. Did I miss why 100 ohm resistor was used ? Also if i put NPN by 180 degrees, will it work the opposite way i.e. led on only when it is day? something I will try

Thank you.

How do you calculate the resistor values if I used say 3.3V input?

Hi, great vid, I would like the LED to go on when the LDR goes from dark to lit. Is this as simple as reversing the LDR?, thanks

What is the Power consumption when it's sunny/ Led off?

I totally agree with the rest of the commenters. a simple but yet very good tutorial explaining the concept of transistors and current flow. Good job!! oh, and have a great vacation! :-)

So, R1 & R2 are a voltage divider. I know Q1 will probably switch on at .7V, but I don't know what resistance level R2 must be at to cause Q1 to switch on & off. At which actual resistance amounts must the photoresistor be at to cause the transistor Q1 to switch on & to switch off?

can the circuit be revised to turn on MOSFET when the light on the photoresistor is activated. Working at 12 volts

Amazing

Excellent Tutorial. I finally successfully implement Thanks a lot. I search all the net but not work any implementation but your tutorial is finally worked. Thanks again. Now i have a question that how can i connect PIR sensor with this diagram. Because when dark come then pir sensor activate the light . So how can i do this.

Thanks 👍

Thank you! Your video is the only one I found that explains HOW the circuit works and the path that the current follows. I finally made it. I used a 12v LED bought from a store and a power bank with 8 AA batteries, with no resistor after the LED.

Adding a diode really makes this circuit work.

Can I do this with more than 1 leds?

WHat I should do, if I want to use it in my car. But I need it on 12V

Worked good for making fake night vision cameras thanks!

hi! when i connect the component, the LED already turn on without/with me covering the LDR. So, any suggestions?

can i add buzzer to it?

nicely explained - thanks.

Can we use a 9v battery instead of 4AA batteries?

Why is the LED not bright when using this circuit? If using a 1k trimpot with LED, LED is super bright, but with your circuit even with 100 ohm resistor from transistor to led its weak. Help please.

hey! what should i use to light up 10 leds using ldr?

in series or parallel

If I use different npn transistor then will the setup of registances change?

The center leg on transistor is ran to both resistors. But why do each resistor go to different sources? (photo to ground and resistor to pos).

What changes do I need to make in ratings of the components if I want to use a 10W LED???

hi i want to make LED flash using a 20 or a 30 watt w LED.... i wish to have to trigger the LED ON/OFF using a phototransistor as a trigger....can u suggest a circuit.... (am trying to build a simple LED FLASH for cheap diy photography)

nice project! with best explain... how can we make same project but with 12v battery? we use mosfet or just n transistor?

how if input input voltage is 24vdc?

your enlish is verry charm and beautiful ...btw can i use 9v batery ?

It works

so what if I want to do the opposite? what if I want the led to be on when it is light or what I really want to do is power a solenoid with a laser pointer.

Is it necessary to use the resistors and the transistor

hello, can i use 9v of battery?

Nice

Sir plz tell how many led's i can use in this project

Hello! I was wondering if i need a resistor 1/2 w, 1/4w 1 w, or if that didn’t matter. Thanks

how could you add a pot to make the led dimmable

So , in Day time Current draining through LDR ? due to low Resistance ........PLZ ANS if anyone can explain it

how does i control the sensitivity?

Is there a way to make this work with 1 AA battery?

My led stays on and only shuts off with a flashlight directly on the photoresistor? Can someone help?

My led turns on when there is light present and turns off when no light is present.. what is the problem?

Not working :(

What would be needed to create a 120V system? and how would that circuit look?

Is there a reason why this does the exact opposite of what it's supposed to do? Do I have the wrong kind of photoresistor?

Sloud it work with bc547?

can I use 9V battery??

A switch? That black thing?

I guess im stupid because my LED just powers straight on despite the photoresistor and I have no idea why

Write a program for the above circuit

Fun

oreo binteo!

It's wrong to put the load on the emitter rail of a transistor. Put it on the collector rail.

It is not working

not working waste

Don't waste your time. This circuit does NOT work.

Finally someone who can speak English clearly