12v 2.5w max load LDR auto on dark detecting switch

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05:12:41

This is a dark detecting switch with a max load of 2.5 watts. The load here represented by the 1.2 watt lamp. I am using a 1.2 watt 12v led (10 watt halogen replacement lamp) found on amazon. The 200k resister is representing a LDR also found on amazon. The MOSFET is a 2n7000g, and the NPN transistor I am using is a 2n222.  This circuit is tuned to turn on at about 1 lux. Adjust the lower left resister (LDR) to watch it turn on and off between 145k and 160k. While in standby this circuit only uses around 35uA. Enjoy!

published 8 years ago

jason9

8 years ago

What if the light produced feeds back into the light sensor?

rogersmith

8 years ago

I place the light sensor above the light like the ones you see in common solar yard lights. Works like a charm.

hurz

8 years ago

2N2222 ?

rogersmith

8 years ago

That's the npn transistor part number.

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