Silly question about voltage and current

[Farmhand]

If you want the voltage of two supplies then you have to put them in series, and the loop current will be limited by the supply with the lower current limit.  A 25kV 1mA supply in series with a 2V 150A welder will still only deliver 1mA.  If you want the current of two supplies then you connect them in parallel, and you will be limited by the lower voltage of the two.

Umm you don't need to tell me that.  But is that what the original poster wants or is talking about ?

I think he is talking more about a HV in parallel with a LV maybe the HV as HF as well, I'm not sure. I'm hoping the original poster will post a drawing of what he is visualizing.

This below is what I think they mean when they talk of mixing HV with LV. Don't forget, it is no me making the claim here. First I am trying to understand what the original poster actually means.

Maybe he will say if my drawing represents his thoughts. It could be considered without the smoothing capacitor or with.

In my opinion it's a pointless exercise. Unless there is some reason for it that I cannot see. 

..

[Farmhand]

Here's an example, If we begin with the LV supply turned off and the Load resistor drawn near the ? on the drawing is 10000 Ohms then the capacitor will charge to about 1000 volts and about 0.1 Amps will flow in the load resistor. about 100 Watts. Then if we turn on the LV supply nothing will happen, because the capacitor is already charged to 1000 volts. The LV supply will draw idle power. That's what I say.

Now if we do it the other way and have the LV supply powering a 100 ohm load and dissipating about 1 Watt. Then we turn on the HV supply we could have a problem with fire or supply capabilities, or just use more power (10 kilowatts) and drive the load harder with the HV supply. 

Cheers

[MarkE]

Umm you don't need to tell me that.  But is that what the original poster wants or is talking about ?

Those are the only two options available:  Series or parallel.

I think he is talking more about a HV in parallel with a LV maybe the HV as HF as well, I'm not sure. I'm hoping the original poster will post a drawing of what he is visualizing.

This below is what I think they mean when they talk of mixing HV with LV. Don't forget, it is no me making the claim here. First I am trying to understand what the original poster actually means.

Maybe he will say if my drawing represents his thoughts. It could be considered without the smoothing capacitor or with.

In my opinion it's a pointless exercise. Unless there is some reason for it that I cannot see. 

..

I think that the person proposing the scheme does not understand that all practical voltage sources have internal impedances that limit their current. 

[Farmhand]

Mark ,Even to a novice it should make no sense to connect a thin wire from say a flyback secondary in series with the thick wires from a step down transformer secondary.

It is true the impedance of the supplies will see the HV supply restricted in output current and at some point the voltage will drop. But for the sake of the argument we can consider both transformers capable of outputting say 1000 watts each or we could consider them ideal and thus they would handle any load, just to keep it simple.

We can see that in the first case of the LV off to start with then turning the LV on while HV is already on and the load resistance is high makes little difference due to the counter emf of the already charged to 1000 volts capacitor would prevent any power output from the LV supply.

I think if we want people to understand more we need to give examples and explanations in layman's terms, eg, in my example the counter emf situation shows up another myth which is that counter emf (the evil twin or the evil witch as UFO calls it)  consumes power, when in fact it only restricts the power, counter emf does not consume power and any emf countering an applied emf is counter emf, be it induced or already present.

If we just say no it won't work and give technical explanations that most people do not understand then next to nothing is achieved. People don't just trust the words of a "naysayer" such as we, like they trust the words of the guru scammers. We must work to get the point across.

I am always amazed when a trained guy comes along and lumps me in with the claimants of OU or suggests I am making claims, when all I am doing is trying to explain how I see things in layman's terms.

I suggest if you want a strictly engineering interaction then go talk to an engineer. No offence but you cannot expect to talk engineer speak to laymen or complete novices and have them just accept it. If it bothers you not that the same fallacies keep arising then keep not explaining it so people can understand. This mixing of HV-LC and LV-HC has been claimed before by others and i challenged them to show it but was personally abused.

You should be aware Mark that I am on the side of (proof of claims and better understanding of basic electronics) as a means to reduce the effect of the Guru scammer type people and the eternal promise with no evidence - keep a thread going for ever type people, as well as helping others to be more discerning experimenters able to spot a fake or a mistaken claim.

Cheers

[TinselKoala]

The system in the RM503 scope is something like that shown below. I haven't put in the capacitors, etc. and I've shown it as a positive elevation instead of the negative "elevation" used in the real scope. The filament is elevated to -3000 v wrt the scope's chassis ground; this supplies the electron current needed to make the electron beam. The filament gets its AC heating current from the 12 v transformer, which can supply its full rated output to a load, and the filament gets the DC beam current from the HV transformer (really a voltage multiplier system) through the HV rectifier tube and this can only supply a small current.

Needless to say, the insulation in the 12v transformer has to be good.

The loops described by Farmhand are here; they share one "leg" in common. If you could be an electron in that common leg... you'd probably get pretty confused. But it works, anyhow.