Pwm Circuit Using 555. From the above circuit diagram of 555 timer in astable mode it is clear that the capacitor is charging through r1 and r2 while it is discharging only through r2. Simple circuit for dc motor speed control fan speed control light led dimming and etc using the 555 timer also a good starting point for novices wanting to get their hands dirty with the 555 timer ic.
In this method the average voltage delivered to the load is controlled by varying the duty cycle of the rectangular wave. Below formula is used for deriving the frequency of the pwm signal. Capacitor charging through d1 diode and discharge through d2 diode will generates pwm signal at 555 timer s output pin.
The circuit is very simple i have used 555 ic and some basic electronics components to make this speed control of dc motor using pwm.
Here i have used tip122 npn power transistor but you can also use irfz44n mosfet. The circuit is very simple i have used 555 ic and some basic electronics components to make this speed control of dc motor using pwm. The basic idea is to vary the input signal which is supplied to the control pin of the ic. Ne555 timer ic is working as an astable multivibrator here.
