Zedone
New Member
How can we make an analysis for this circuit. Can we make something mathematical? here briefly first 555 behaves astable, second 555 acts as monostable. Transistor acts as swithcing circuit. What we need to do to analyse the circuit? especially in mathematically. thanks. (ciorcuit is in the attachment. or here **broken link removed**)
it says:
Designing a PWM Circuit
The concept of PWM inherently requires timing. Two 555 timer ICs and some potentiometers can be used to generate a PWM signal, and since PWM provides a digital, on/off signal, it is also easy to use a PC or micro-controller to create the signal; however this is beyond the scope of this article.
The circuit in figure 2 uses two 555 ICs and is actually a combination of two types of circuit. The first is a free running multivibrator (astable) with an adjustable frequency around 30Hz. The output of this circuit then triggers a pulse shaping (monostable) circuit which adjusts the width of the pulse. The circuit produces a duty cycle in the range of approximately 0.3% to 97%.
The speed of the motor is controlled with a single potentiometer (variable resistor). It is possible to run a Meccano M5 motor to test the circuit, and it will run from dead still to full speed using the potentiometer speed control and a 6V battery as the sole power source. If you have a 12V motor, you can of course use a 12V power source.
The motor is switched on and off via a TIP31C transistor (shown in figure 3) which can handle motors rated up to 3A at 100V, or a total power of 40W. If you are using a high power motor, make sure there is a heatsink bolted to the transistor.
it says:
Designing a PWM Circuit
The concept of PWM inherently requires timing. Two 555 timer ICs and some potentiometers can be used to generate a PWM signal, and since PWM provides a digital, on/off signal, it is also easy to use a PC or micro-controller to create the signal; however this is beyond the scope of this article.
The circuit in figure 2 uses two 555 ICs and is actually a combination of two types of circuit. The first is a free running multivibrator (astable) with an adjustable frequency around 30Hz. The output of this circuit then triggers a pulse shaping (monostable) circuit which adjusts the width of the pulse. The circuit produces a duty cycle in the range of approximately 0.3% to 97%.
The speed of the motor is controlled with a single potentiometer (variable resistor). It is possible to run a Meccano M5 motor to test the circuit, and it will run from dead still to full speed using the potentiometer speed control and a 6V battery as the sole power source. If you have a 12V motor, you can of course use a 12V power source.
The motor is switched on and off via a TIP31C transistor (shown in figure 3) which can handle motors rated up to 3A at 100V, or a total power of 40W. If you are using a high power motor, make sure there is a heatsink bolted to the transistor.