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Such Soldering!
Will add the little trim pots on the next version, so that you can set the sensor to room ambient lighting. Some of the headless lounges were not as brightly lit, and the fans were idling at about 1/4 power instead of turning off completely.
Lil phillips or thumbscrew 200k pots would be ideal ^.^
Will add the little trim pots on the next version, so that you can set the sensor to room ambient lighting. Some of the headless lounges were not as brightly lit, and the fans were idling at about 1/4 power instead of turning off completely.
Lil phillips or thumbscrew 200k pots would be ideal ^.^
Category All / All
Species Unspecified / Any
Size 1280 x 720px
File Size 274.7 kB
maybe i'm late for the party ... the PWM pin (on 4-pin fans) is internally pulled high. if you pull it low, the motor is turned off. so you put a transistor on it that pulls towards ground, and feed it a (20-30 kHz or so) square wave. the more "high-time" the signal has the faster the fan goes, obviously, but you can also use it for on-off control without switching the main power rail. there is a bunch of ne555 based circuits around the net that can generate suitable PWM signals. (extra points if you can use the 555 discharge pin for driving the fan PWM pin)
Correct. A tip103 darlington transistor. The trigger is set by the resistor and photocell, set up as a voltage divider. A very low level logical gate sorta deal. :)
By adding a potentiometer, we can move the 'sweet spot' to trigger it. Darker or lighter, depending on the real conditions of the spot you place it.
By adding a potentiometer, we can move the 'sweet spot' to trigger it. Darker or lighter, depending on the real conditions of the spot you place it.
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