voltage booster help needed

bertus

Joined Apr 5, 2008
22,923
Hello,

The bipolair NE555 will not work on 3 Volts.
You will need a cmos version like the LMC555, but that has limited output current.

Bertus
 

DickCappels

Joined Aug 21, 2008
10,661
The LMC555 will. Since there is a buffer on the base drive to the output stage you can use your multivibrator.

The schematic below (click on thumbnail) is your circuit tweaked to deliver 5.2V @ 500ma. You can vary the output voltage by varying the duty cycle of the pulse out of the oscillator. The oscillator should run at about 30 kHz, starting with a 50% duty cycle since the step-up ratio is close to 2:1. Notice the 6.2 volt Zener diode across the output. This should protect your phone from getting zapped, but please experiment and get to know the circuit before connecting something like a cellphone.

many 2n2222.png
Th 0.05 ohm resistor in series with the inductor is an estimate of the resistance of the inductor. The resistance affects the load dependent regulation, the amount of overshoot at startup, and the efficiency.

There needs to be a large capacitor across the battery.
 

DickCappels

Joined Aug 21, 2008
10,661
Incidentally, the 10 ohm resistor is not part of the power supply -it is a test load, so you would not have that in the finished supply.
 
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