hi
i want step up voltage from 3.3v to 6v...so i made charge pump but i put 2222 transistor instead of diode...now every thing work fine and i have 6.1 volt ..no problem with circuit...but i am afraid that the transistor may be damage because the "Emitter-Base Breakdown Voltage = 5v" i am really don't understand what Emitter-Base Breakdown Voltage are???

here is my circuit

 

Emitter-base breakdown voltage is exactly what it says. If the emitter-base voltage exceeds 5 V, then it may break down and start conducting current.

 

so i have to put Schottky diode between the transistor and the cap to protect the Emitter from exceeds 5 V

sure?
it works fine now and nothing happen to 2n2222

thanks

 

At what point does Veb exceed 5V now?

Have you looked closely at your output voltage on a scope?

 

hi
i don't have a scope....voltmeter only

 

Put the diode in series with the base.
That way you will still protect the emitter but won't reduce the output voltage.

 

Put the diode in series with the base.
That way you will still protect the emitter but won't reduce the output voltage.

and the emitter will not damage? that will protect it for sure?

 

I don't understand how the circuit could work, the base is floating and the transistor never conducts.
Is the diagram correct ?
What is the 20Hz voltage on the base ?

Edit: Forget the former sentence about the base, but this circuit won't charge or pump

 

To double the voltage, Q1 must be a PNP transistor, emitter to +3.3V, from collector a diode to another capacitor, the base voltage pulsing from 0 to 3.3V.

 

and the emitter will not damage? that will protect it for sure?

Yes.