It's all in the datsheets, you just have to look.thanks.and what can be the transistor you said?
Your words fail to communicate what you are talking about. A picture is worth several thousand words. Also how do you define and measure efficiency?the classical one transistor tapped coil circuit
2 transistors. But...ok.but is there a way to make a joule thief more efficient by adding capacitor or other resistor?? or making the circuit LC resonant?