Way to add a motion detector module to a 555 dimmer circuit with led strip as load

Thread Starter

FranciscoB

Joined Feb 8, 2014
94
I have read Wendy's blog entry regarding the use of the 555 for PWM. Have also read the following topic regarding handling larger loads:

http://forum.allaboutcircuits.com/threads/dimming-led-strip-with-555timer.19485/#post-121823

In my case, the load will be the following (5 meter, 300 LED led strip working at 12v, max 2A):

http://www.banggood.com/5M-White-3528-SMD-LED-Strip-Light-Non-Waterproof-12V-DC-300-LED-p-77079.html

1) I would like to ask if the following Mosfet can be used instead of the IRF510, as it's what I have here:

http://alltransistors.com/mosfet/transistor.php?transistor=19301

2) I would also like to add a motion detector module, the HC-SR501:

https://www.mpja.com/download/31227sc.pdf

I am not sure how to use it to trigger the 555 in PWM configuration ON when the sensor detects motion.

In the end I would like to have a led strip that I could dim to my preference and that would turn ON when detecting motion at night. It would be particularly useful if I could have a switch to bypass the motion detector system, when I need the leds to stay ON all the time.

 
Last edited:

DickCappels

Joined Aug 21, 2008
10,152
If the LED strip really draws two amps, you could drop up to six volts across the SMD0456F. Of course that would cut the voltage for the LEDs iin half...

MOSFETS with much lower on resistance are available and not expensive. For example the STP55NF06 is only 0.015 ohms and would make a much better switch. It would not even need a heatskink for your application. My disstributor in Thailand lists it for about US$0.25 each in quantities less than 25.
 
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