Russian voltage multiplicator stacking

[nix85]

I been watching EEV's video on Cockcroft Voltage Multiplier again.

It's a great vid and among other things he makes clear upper side is pulsating voltage and bottom side is steady dc. He explains why in the beginning of the vid.

https://youtu.be/ep3D_LC2UzU?t=723

And then i stumbled on this russian craziness.

https://www.youtube.com/watch?v=ibJYu5fvHkk

So they used this 3 stage multipliers from old TVs. You can see in the diagram is missing first top capacitor, but i guess that's a mistake.

What i find strange is how they connected them.

To stack them they drilled a hole marked A in diagram, which is presumably the top part of the last stage, and they connected it to "ground" of the next multiplier.

They also connected bottom side of the last stage marked + to top side of next multiplier.

I made a diagram to compare normal 4 stages to how they connected them. I used 2 and 2 instead of 3 and 3 but same thing.

I find it strange and it sure does not look like the same circuit like normal 4 stages.

But it obviously works, so they obviously know what they're doing.

If someone has experience with these multipliers i would appreciate if they explain this.

Opinions are welcome.

[citfta]

 

[nix85]

Hi Nix,

The guy in the video is not exactly right about the signals.  There are pulsing DC signals on both the top and bottom of the circuit.  The output is also pulsing DC.

To start with irony relative to your concluding comment about online education, you are WRONG. Bottom side provides constant dc, not pulsed dc, when input goes negative, capacitor in parallel provides +2v until the next positive halfcycle.

Here is a short explanation of how the circuit works.  I have modified your drawing with some numbers for the caps and the diodes.  The signal coming into the circuit is AC.  During one half of the cycle C1 gets charged when the side next to D1 gets a positive pulse from D1 while the AC side of the cap gets a negative pulse.  On the next half cycle C1 will discharge into C2 through D2 when the AC side goes positive and the other side of the AC signal goes negative.  Since C1 was already charged up to the supply voltage and since it is series with the supply then C2 will get charged to the voltage of the supply as well as C1.

During the next half cycle C1 will again get charged to the supply voltage and at the same time C2 will discharge into C3 with the same voltage as the supply.  Now both C1 and C3 are both charged to the supply voltage and since they are in series we now have a voltage on C2 in reference to the supply that is twice the voltage of the supply.  And with each half cycle the next caps in the series get charged up until you get all of them charged.  But the output is still a series of pulses if you apply a load on the output.

And who asked you to preach the basics of the basics that are already explained in the video i linked. Here is a video for you to better understand what really happens.

https://www.youtube.com/watch?v=IqzA3-bgIIE

Now the Russian diagram is a little confusing but if you take the second half of you bottom drawing and flip it over while leaving the connecting wires the same you will see that all you really have is the same circuit except the last diode of the first section is now in parallel with the first diode of the second section.  So in effect you have just lost one-half cycle of charging for the caps which just reduces the output voltage by the same as the supply voltage.

Last diode of the first multiplier and the first diode of the second multiplier are switched on in parallel and work as one diode.

It's the bottom caps that provide the output voltage and since there are still 6 caps on the bottom so there is no loss.

If you have a way to tap into the different caps you can actually take the output from the positive side of any one of the caps.  The voltage will just be different depending on how many caps are between your output and the supply.

Also said in the video i linked and duuh. Also 1+1 is 2, imagine.

I hope this has helped some.

Nope, you just repeated what is already said, and did it wrongly.

As a side note a good online class in electronics is a much better way to learn electronics than Youtube videos.  A lot of videos on Youtube are put out by people that don't really know what they are talking about.

Good luck,
Carroll

Ironically it turns out you don't really know what you're talking about.

Good luck

[citfta]

 

[nix85]

You don't know what you are talking about. I drew the diagram correctly. I only did not include the capacitor because russian diagram does not include it but that is most likely their mistake.

Secondly, it's not me saying output is dc, it's David from EEVblog and he explains why. Like i said, when input goes negative, there is +2V on the second cap to provide constant dc. There sure will be bit of ripple, but basically dc.

And no, i don't know it all nor i claimed to.