Nikša asked in Science & MathematicsEngineering · 4 months ago

# Voltage multiplier question?

Let's see exactly what happens, when C1 charges to 12V, now source changes direction, if there was no other cap, C1 would now discharge and charge to 12V in other direction. All sweet and clear.

But since C2 is there, 12V from the source + 12V on the cap (now in same direction) charge C2 to 24V, and yet this does not discharge the C1 and charge it in other direction. I find this very strange.

Update:

I know they don't charge instantly, it takes multiple cycles indeed. Still question remains, let's look from moment C1 and C2 are fully charged, fully charged cap is not supposed to conduct, yet they do and all other caps get charged through them.

Update 2:

CORRECTION, C1 DOES discharge when charging C2 to 24V. I was misinformed by youtube guy The Organic Chemistry Tutor.

Update 3:

Ci DOES discharge, here is exactly what happens...

When C1 and source charge C2 to 24V C1 is now discharged but on next (negative) halfcycle C1 is charged to 12V again. AT THE SAME TIME (in parallel) 12V from source + 24V on C2 charge C3 to 24V (36V - 12V on C1). This discharges C2 but on next (positive) halfcycle it gets charged to 24V again and at the same time 12V from source + 12V on C1 + 24V on C3 charge C4 also to 24V (48V-24V). And so on in same manner.

Relevance
• 4 months ago

Remember that the voltages do not appear instantly!

For the first few cycles when everything starts at zero volts, C1 may experience reverse polarity for part of each cycle, as the other capacitors gain a bit of charge from it at each half cycle.

It's only after C2 has reached the same voltage as the input positive peak or more than the polarity never reverses across C1.

If the output were shorted (or overloaded) it may cause C1 polarity to reverse during every positive input half cycle, as the other caps can never build up any appreciable voltage then.

• 4 months ago

C1 charges to 12V through D2 and C2Now the voltage changes direction but c1 does not discharge because D1 does not allow it. Current flows through C2, D3, C3 and C1...

This stuff is tricky...