charge pump help need

Thread Starter

hertz.12

Joined Apr 25, 2015
41
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

pump.jpg
 

WBahn

Joined Mar 31, 2012
26,068
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.
 

Thread Starter

hertz.12

Joined Apr 25, 2015
41
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
 

jjw

Joined Dec 24, 2013
542
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 :)
 
Last edited:

jjw

Joined Dec 24, 2013
542
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.
 
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