Hello fellas, i'm building a LDR circuit following my teacher's diagram, but i don't know what i did wrong, can you help me?

Thread Starter

Electric_Mat2007

Joined May 16, 2024
8
Here's the circuit from my teacher
98798.jpg

And here's the circuit i built on ISIS

AJJJJJJJJJJJ.PNG

I don't know if i'm using the wrong components or values, i need this for a school work here some more details:

10k Potentiometer
Transistor BJT BC547
And i believe most of details are on the image already

My knowledge is very limited in electronics
 
Last edited by a moderator:

Thread Starter

Electric_Mat2007

Joined May 16, 2024
8
Update: I added a new 10k resistor between the pottentiometer and the base leg from the transistor, the LED lit up, but when i aproach the light it doesn't turn off :(
 

Thread Starter

Electric_Mat2007

Joined May 16, 2024
8
I am not familiar with your software. Are you able to similulate a light source for the sensor?
So, you know the "latern" with two arrows, one up and one down? SO that's the light source that points directly to the LDR, the up arrow is to approach the light to the LDR and the down arrow is to make the light far away from the LDR, do you get it?
 

Thread Starter

Electric_Mat2007

Joined May 16, 2024
8
Look at your circuit and the circuit from your teacher that you posted.

Are they the same? If not, what’s the difference? I see a wire missing.
Ah i see, that wire in the middle of the pottentiometer, i tried to draw a line between the potentiometer and the base leg, it was denied by proteus, then i put a 1k resistor between the potentiometer and the base leg , and after that, i'm stuck now
 

djsfantasi

Joined Apr 11, 2010
9,185
Ah i see, that wire in the middle of the pottentiometer, i tried to draw a line between the potentiometer and the base leg, it was denied by proteus, then i put a 1k resistor between the potentiometer and the base leg , and after that, i'm stuck now
Show your “new” schematic with the 1k resistor
 

Alec_t

Joined Sep 17, 2013
14,398
How do you set the pot's wiper position in Isis? If the wiper is too close to the positive rail the LED will never turn off.
 
Last edited:
let’s go back to the poorly drawn sketch. No voltage indicated on the battery but your 9V makes sense. But if the 10K pot is turned all the way to zero ohms then 9V into the base of the transistor is not a good look. There should be at least a 1K resistor in series with it. Hopefully you have not blown the transistor
Assuming you don’t have a meter to test the resistance of the LDR, as already suggested by Wendy, maybe try replacing it temporarily with a 470R resistor with the pot set half way. The LED should light up. If you then increase the resistance of the pot the LED should dim and go out. If this works you can then address how the LDR is affecting the result.
I urge you to stay away from simulation software until you really have a good understanding of electronics. And randomly inserting additional components is not good practice either
 
Top