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Pulse Width Modulation - Light Dimmer/Digital Dummy Load

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This is a simple 555 IC Pulse Width Modulation (PWM) Light Dimmer Controller cum Digital Dummy Load cum DC Motor Speed Controller. The original idea of this circuit as a Light Dimmer / DC motor speed controller. With a bit of innovation mind, I added another function for this circuit. Digital Dummy Load was born. I've added 2 pcs 1 OHM 10W resistor to form the load (More can be added depends on the application). I can control the current passes through these resistors by varying the PWM hence the ON/OFF time of the Power MOSFET (BUZ11). The minimum pulse width is 5% and the maximum pulse width is 95%. That is the reason why you see the lamp lighted up dimly and 270mA of current drawn from the power supply (12V) in the case of Digital Dummy Load Setup when power up. I can adjust the amount of current drawn from the power supply safely as long as Ii kept the power within 20W which is the resistor power. The MOSFET can handle this power safely without heat sink. The good thing about the Digital dummy load is I can adjust the amount of current passes through the load in a controlled manner. For example, I can set the current drawn from the power supply at 1.35A easily and safely. Enjoy...

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