Hi,
This is my first post, I have searched the forum for answers but can't find quite what I need. I would appreciate if anyone could give me some advice.
I'm attempting to make a speed controller for a fan(20vdc, brushed)
I was hoping to modify a circuit on this website:http://ourworld.compuserve.com/homepages/Bill_Bowden/page6.htm#dimmer.gif
The power is coming from a 20v transformer that I have rectified to dc.
The problem I have is that the 555 can only handle max 15v so I need to lower the voltage to the control side of the circuit somehow whilst still supplying the motor with 20v(pulsed)
Can I just use a resistor in series? if so, how would I calculate the size required?
Also, what is the best frequency to use for controlling the motor speed, this circuit states 200hz. I have read on somewhere that 20khz+ is best for motor speed control? I'm assuming I can change this by using a smaller capacitor?
Thanks
This is my first post, I have searched the forum for answers but can't find quite what I need. I would appreciate if anyone could give me some advice.
I'm attempting to make a speed controller for a fan(20vdc, brushed)
I was hoping to modify a circuit on this website:http://ourworld.compuserve.com/homepages/Bill_Bowden/page6.htm#dimmer.gif
The power is coming from a 20v transformer that I have rectified to dc.
The problem I have is that the 555 can only handle max 15v so I need to lower the voltage to the control side of the circuit somehow whilst still supplying the motor with 20v(pulsed)
Can I just use a resistor in series? if so, how would I calculate the size required?
Also, what is the best frequency to use for controlling the motor speed, this circuit states 200hz. I have read on somewhere that 20khz+ is best for motor speed control? I'm assuming I can change this by using a smaller capacitor?
Thanks