Introduction to LDR or photoresistor and how to Turn ON something with light

This video introduces LDR or photo resistor and how to turn on LED or other devices
See GL55 Series LDR Datasheet robojax.com/download/datashee...
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Introduction to LDR: [this video]
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[@user-im3jb5de6b]

Thanks

[@plasticelectrics]

thanks for helpful video... i am using the LDR turning on a LED when it goes dark.... but it only seems to work without the 91ohm resistor ? any ideas

[@robojax]

If it works and stable, that is okay. The 91Ω resistor at the Base of transistor makes it stable.

[@MagicSmoke11]

Great Explanation Robo 👍.So the Normal Photodiode modules available in market are those decreases Resistance (Voltage increades ?) when light fall on it

[@robojax]

Yes, correct

[@marianohernandez198]

nice video..it matters which way connecting negative or positive

[@robojax]

the LDR doesn't have polarity. You can connect it any ways you want.

[@gmohan3745]

Mariano Hernandez 1

[@bobbroedel3594]

good job brother

[@robojax]

You are very welcome brother.

[@wflores9711]

Thanks!

[@robojax]

Welcome!

[@belalsmart7138]

Thanks,

[@robojax]

You're welcome!

[@JoeStanfordDoughty]

Hello Robojax.
I have been trying to do this for a few days now, followed a few tutorials but have the same problems.
First the 10K potentiometer doesn't seem to work for me, as in the LED is turning on way too bright, I almost went to 300K resistor(trying without potentiomenter) to get the correct brightness on/off.
Second, I would like the light to go ON/OFF, but as evening approaches there is a range of darkness where the LED is slightly on not 100% and little by little this brightness increases as the darkness increases. I would like it to go from 0% to 100%
Any help much appreciated

[@robojax]

Hello Joe,
I don't see problem if you followed the instruction. I assume you the exact transisitor and supply voltage is correct. The problem could be 1-the 91Ω resistor check the value and make sure it is connected. 2-the pot is bad. check it using multimeter. Goog luck

[@1Richmar]

use a micro-controller such as the Arduino nano (pack of 3 for $12 on amazon) to take photoresistor as input and based on value, send output to led.

[@rudyjrbagadiong8225]

Nice demo sir, Can you please tell sir what formula for this one, Thanks

[@robojax]

Hello, I am not sure but I must have used Ohm's law.

[@rudyjrbagadiong8225]

@@robojax okay sir. iam trying hard to get the 680 and 91 ohms using ohms law sir and still cannot get it.if you cangive an idea on how sir, muchly appreciated. thanks

[@salvagehitech7367]

Hi , If my input voltage 24vdc what is the resistor need to be use

[@robojax]

Hi, I presented the value of resistor in total dark and full light. you use ohm law and calculate the current for 24V it is very simple. if total power is less than 0.025W, then you can connect it.

[@binodshaw6174]

Sir what is gl 5539 photo resistor and the difference between ldr

[@robojax]

I've just added the link to the datasheet in the description of video.

[@jagadishmallemoggala328]

Wht is the blue regulated part.?

[@robojax]

at 05:50 mentioned and again at 07:05 (click on 07:05 to see it)

[@rizwanhashmi8011]

what is ldr k. ohm value

[@robojax]

the ohm (Ω) value depends on type and darkness and ligh. See specs goo.gl/3pNB97

[@jagadishmallemoggala328]

Ldr is nc or no.?

[@robojax]

it is NOT relay to have NC or NO. (NO= Normally Open, NC=Normally closed)

[@abrahamlincoln4894]

I've never seen such a photoresistor

[@robojax]

in 1850 it did not exist (if you are Abraham Lincoln). it is very cheap and easy to use.