This is a new area, of learning, for me... So, think noob...
This is not my homework. I need this information, for my current project… A voltage rectifier/regulator, for a computer-style fan.
I have a 12vac voltage source. It is half-wave rectified, to dc. I want to use a capacitor, to fill the 50% duty cycle, to run a 12vdc computer fan.
Have I calculated this, correctly?
Calculate voltage available. How does the 50% duty cycle effect this calculation? 0.4 x ½ = 0.2; therefore the factor should be 1.2, not 1.4?
Xvdc = 12vac x 1.4 = 16.8vdc
Xvdc = 12vac x 1.2 = 14.4vdc
Or, maybe use 12/2 = 6 volts, times one of the above?
Calculate watts needed. Assume 1/2a draw, for the fan.
12vdc x 0.5a = 6w
Time – Half Wave Rectifier
60Hz/2 = 30Hz = 0.0333 seconds
Calculate Joules
6w x 0.0333s = 0.1998j
You should only use the first 1/3 of a capacitor’s charge? Is this accounted for, in the needed joules calculation?
3 x 0.1998j = 0.5994j
Calculate capacitance, for the needed joules, and resistance, for the needed time. Are either of the below calculations correct? If so, which one? If not, what needs attention?
Because the zener is in the circuit, the cap will never see higher than 12vdc? So, the calculation should be based on a 12v starting point. Correct? Is the clamp schematic correct?
Thank you, for your help...


