I am trying to increase the output current of this charge pump circuit but I am out of ideas

Once C1 (10mF) is charged up to roughly 3V the mosfet will open up at random intervals for 400ms thus powering the buzzer with a peak current of roughly 30mA. The circuit works fine without the charge pump but it's a little quiet. If I can get 1 or 2V more I can increase the sound by a few decibels. The 3V come from a coin cell.

C2 and C3 are 47uF and the pumping frequency is 50kHz. Increasing these values does not do much. The diodes are schottkys. I can just barely keep the voltage across a 1kOhm resistor high enough for my required time but the circuit will have to drive a 100 Ohm equivalent load (the buzzer) I can't add another charge pump stage as the buzzer's max rated voltage is 6V and frankly I don't think it would lower the output impedance by much.

What can I do if I don't want to use an IC? On the internet I have seen charge pump circuits using H bridge arrangements but I didnt find any info on their output current capabilities.



1 Answer 1


A boost circuit using an inductor would probably be a better solution for you, especially considering the low starting voltage you have to work with. Look up 'joule thief' for examples.

  • \$\begingroup\$ Good idea, but I am wondering if a joule thief can work if you power it with a 2.5kHz square voltage \$\endgroup\$
    – crispus
    Commented Dec 1, 2023 at 23:26

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