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Step 5How is a Compact Fluoresent Different?
So what's different about a Compact fluorescent?
A CFL tube is pretty much the same as a straight fluorescent; it's just folded up.
To make the ballast smaller, we have to shrink the inductor somehow. Since the current is proportional to the inductance AND the frequency, we can make the inductor smaller just by increasing the frequency! Basically, the electronics in a CFL (or in an "electronic ballast" for conventional fluorescents) contains a circuit that will make HIGHER FREQUENCY AC from the normal 60Hz input.
Typically, the AC input is rectified and filtered to High Voltage DC (HV diodes, electrolytic caps), and then some sort of oscillator (other caps, toroid, small inductor) is used to drive some HV transistors to produce a final output that is still about the same voltage, but at a much higher frequency than the original. This way, the final current-limiting inductor ("big inductor") can be much smaller.
A CFL tube is pretty much the same as a straight fluorescent; it's just folded up.
To make the ballast smaller, we have to shrink the inductor somehow. Since the current is proportional to the inductance AND the frequency, we can make the inductor smaller just by increasing the frequency! Basically, the electronics in a CFL (or in an "electronic ballast" for conventional fluorescents) contains a circuit that will make HIGHER FREQUENCY AC from the normal 60Hz input.
Typically, the AC input is rectified and filtered to High Voltage DC (HV diodes, electrolytic caps), and then some sort of oscillator (other caps, toroid, small inductor) is used to drive some HV transistors to produce a final output that is still about the same voltage, but at a much higher frequency than the original. This way, the final current-limiting inductor ("big inductor") can be much smaller.
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