tadinya pengen bisa mengontrol kecepatan kipas DC CPU cooler biar ngga berisik, terus googling ketemu rangkaian sederhana pengontrol kecepatan motor DC dengan IC 555 keterangan kaki IC 555 Ground DC Ground Trigger The trigger pin triggers the beginning of the timing sequence. When it goes LOW, it causes the output pin to go HIGH. The trigger is activated when the voltage falls below 1/3 of +V on pin 8. Output The output pin is used to drive external circuitry. It has a "totem pole" configuration, which means that it can source or sink current. The HIGH output is usually about 1.7 volts lower than +V when sourcing current. The output pin can sink up to 200mA of current. The output pin is driven HIGH when the trigger pin is taken LOW. The output pin is driven LOW when the threshold pin is taken HIGH, or the reset pin is taken LOW. Reset The reset pin is used to drive the output LOW, regardless of the state of the circuit. When not used, the reset pin should be tied to +V. Control Voltage The control voltage pin allows the input of external voltages to affect the timing of the 555 chip. When not used, it should be bypassed to ground through an 0.01uF capacitor. Threshold The threshold pin causes the output to be driven LOW when its voltage rises above 2/3 of +V. Discharge The discharge pin shorts to ground when the output pin goes HIGH. This is normally used to discharge the timing capacitor during oscillation. +V DC Power - Apply +3 to +18VDC here.