Yes, it is interesting! The basic circuit isn't hard to understand. However, the touchy items are how to balance C1 and C2 and R1 and R2 in Roman's circuit. I'm not quite sure how to optimize them without a scope. My 1MHz portascope (TPI multimeter with a builtin scope) may be too slow or have too low of an input impedance to accurately characterize the circuit. Plus, I don't have any test loads. High power resistor dummy loads are expensive!
Very cheap though.
As for whether it's better than a 7805, it depends upon whether you value efficiency or not. A 7805 will have less ripple but it will also waste power. If V(in) is 12V and V(out) is 5V, and the output is 500mA of current, then, at best, the wasted power at best is about 3.5W. The 7805 would be supplying 2.5W of power while wasting 3.5W! That gives you an efficiency of about 42%.
The 7805 will, however, provide overtemp and overcurrent protection.
|