Switching power supply with electronic isolation

A transformerless switching power supply for converting an alternating current supply voltage to a regulated direct current load voltage, comprising:

• a) a rectifier for converting said alternating current supply voltage to a first direct current voltage;
• and a first storage capacitor connected to said rectifier for storing said first direct current voltage;
• b) a first switching circuit connected to receive said first direct current voltage, and having a first control input for selectively turning said first switching circuit on and off, and having an output;
• c) a second storage capacitor connected to the output of said first switching circuit;
• d) a second switching circuit connected to said second storage capacitor, and having a second control input for selectively turning said second switching circuit on and off, and having an output;
• e) a load connected to the output of said second switching circuit;
• f) a controller circuit having means for generating non-coincident first and second timing signals, said first timing signals being connected to said first control input to turn said first switching circuit on only during a time interval when said second switching circuit is turned off, and said second timing signals being connected to said second control input to turn said second switching circuit on only during a time interval when said first switching circuit is turned off;
• and
• g) feedback means coupled to said load and connected to said controller circuit, and wherein said controller circuit further comprises means for manually presetting desired load power characteristics, and means for receiving signals from said feedback means and adjusting said second timing signals to deliver said desired load power characteristics to said load in response to said signals received from said feedback means.