Hi everyone,
I'm with a small project with controling brightness of a 3W 12V light bulb.
This i my current circuit. The signal is connected to a microcontroller's PWM output. The resistor, R10 there represents the light bulb. As I have measure the resistance of my bulb is 7 ohm. The microcontroller is producing 50% square wave pulse
The problem is when I measured the voltage across the bulb, I get:
But when I change the resistor, R10 to 1k ohm, the waveform change to what I want:
Question: It the transistor's internal resistance too high and causing voltage drop across my bulb very small?
Also, any optocoupler with high rating of Ic(transistor) recommended?
Thank you...
I'm with a small project with controling brightness of a 3W 12V light bulb.
This i my current circuit. The signal is connected to a microcontroller's PWM output. The resistor, R10 there represents the light bulb. As I have measure the resistance of my bulb is 7 ohm. The microcontroller is producing 50% square wave pulse
The problem is when I measured the voltage across the bulb, I get:
But when I change the resistor, R10 to 1k ohm, the waveform change to what I want:
Question: It the transistor's internal resistance too high and causing voltage drop across my bulb very small?
Also, any optocoupler with high rating of Ic(transistor) recommended?
Thank you...
Last edited: