LED connect to Transistor And Gate circuit. It alway bright.

[mmc01]

I connect LDR and PIR sensor to input of Transistor And Gate circuit and connect 4 LED 12V 1W to output . But LED is alway bright. when have no input from both sensor LED is little bright. So, I pull out input from LDR. when somebody pass PIR sensor it's more bright . And If have input from both sensor it's most bright. I want only ON/OFF LED not want little bright. how to fix it.

 

[goldsmith]

I connect LDR and PIR sensor to input of Transistor And Gate circuit and connect 4 LED 12V 1W to output . But LED is alway bright. when have no input from both sensor LED is little bright. So, I pull out input from LDR. when somebody pass PIR sensor it's more bright . And If have input from both sensor it's most bright. I want only ON/OFF LED not want little bright. how to fix it.

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Hi mmc01

In this case you must use a comparator , comparators can't give you a linear out put it means they only can be 1 ( high ) or 0 ( low ) . ( on or off ) .
Two choices :
1-using an op amp as a comparator .
2- using a comparator ( like LM311 or ... )


Best Wishes
Goldsmith

 

[Audioguru]

The opamp is missing a positive power supply voltage.
The opamp has WAY TOO MUCH positive feedback.

EDIT: Nothing limits the current in the LEDs.

 

[mmc01]

I want to set LED output hight (12V) when input from LDR and PIR sensor is hight only. how to use comparator with this circuit . Can I connect LDR and PIR to opamp? or I have to connect output from TR AND gate to opamp.

 

[goldsmith]

I want to set LED output hight (12V) when input from LDR and PIR sensor is hight only. how to use comparator with this circuit . Can I connect LDR and PIR to opamp? or I have to connect output from TR AND gate to opamp.

I just told you what to do but you didn't try that way ...