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Help needed with a basic photoresistor on/off circuit - 12v DC

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Here's the circuit you need and it includes that round thing in the image above:

PIR-LED-LightwithTx.gif
 
With the correct pir there is a provision to install the ldr within the Fresnel Lens if that's a better option for you.
pir_ldr.JPG
 
For me this simple two transistor circuit is enough and sufficient as comparator based circuit!
Thank you MikeMI: https://www.electro-tech-online.com/attachments/myphotom-gif.91763/
Thanks Willen. MikeMI told me about that yesterday, but I think I can ad the LDR to my motion sensor to activate it for this particular project as it is a simple LED on/off based on motion detection. I will be using the Schmitt circuit for another device I am putting together though. Thanks again.
 
I have my motion sensor functioning properly now. The only issue I am having is that the LED is at approx 30% brightness. It is being illuminated by the 3.3v signal from the motion sensor. The red 5mm LED is rated at 2v and I put 69Ω resistance on the positive leg. When I was testing this last night with 9v, a 2n3904 trans, triggered by the 3.3v signal on the motion sensor on the neg leg and 360Ω resistance, the LED was bright. What am I doing wrong?
As I have stated before, I have minimal electrical knowledge, so please bear with me. Maybe 'current' (amperage) is the issue here? o_O
 
I am about to solder the LDR onto the motion detector board. Is there a pos and neg leg on the LDR? or is it like a resistor, either way......
This is where it solders onto the board (RL):
upload_2017-7-9_12-16-1.png
 
I used the calculator: 3.3Vin Vf=2v desired current = 20ma It says to use a 1/8 W - 68Ω resistor . All my resistors are 1/4W. I am currently using a 68Ω - 1/4w resistor.
Is this why the LED is so dim? Is there a work around for this or do I need to buy 1/8w resistors now? Also how do I determine which leg is POS on the LDR?
 
1/4W is fine and not the cause of the LED being dim.
The LDR can be connected either way round.
 
1/4W is fine and not the cause of the LED being dim.
The LDR can be connected either way round.
Thanks. Any idea why my LED is so dim? Could it be the amperage coming directly from the 3.3v signal on the motion detector? Maybe I should go back to using the 2n3407 trans, trigger it with the 3.3v from the motion sensor, but supply the LED with 9v and 350Ω resistor?
 
I soldered the LDR to the motion sensor board. I then then set up the breadboard as outlined in my post above. All seems to be working properly.... the LED brightness is correct now also.
knock on wood
 
Good to hear it's working.
 
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