I want to design a circuit which is able to generate 8-10V from a power supply of 5V by chargin parallel caps and switch them to series connection (by using transistors) so they reach the desired voltage. I'm not sure how to do this.
This is what I have thought:
Explanation (please correct me when I'm wrong):
- The caps. are put in parallel/series by a series of BJTs controlled by a clock signal (2Hz).
- During the rising edge, Q10, Q12 and Q13 are enabled, and all the other BJTs are off. This puts
C8in parallel with the 5V power supply, so they charge.
- Then, during the falling edge, Q11 and Q2 are enabled and the other BJTs disconnected. That leaves
C8charged at 5V in series (so they should mimic a 10V power supply if I'm not wrong), and in parallel with
C9. As far as I understand, at this moment C9 should be charged until it reaches 10V (ignoring losses).
- When the caps. are in parallel, they are in series with a 220 ohm resistor (
R34). That gives a time constant of
220 ohms * 2e-6 farads). Having that the clock is working at 2Hz, they should have more than enough time to charge I think.
- When the
C8are in series, and in parallel with C9, there is no resistor so they should charge
C9very fast, right? The discharge will be very quick as well, but for now I only want to see some ~8V moments at
- RL is a resistor used to simulate a load.
The result I get at
C9 after the simulation finishes is that it stays at 4V. If I remove C9 and probe the voltage at C7, it switches between ~4 and ~8V depending on if they are in series or parallel due to the action of the clock.