Lower voltage diode the other side of a step up transformer?

I was actually talking about a stepup transformer. 120V to 6000V. Yes it's American, I got it cheap. To avoid finding a 6000V diode, I thought I could use a 120V diode. From all the answers it appears I was wrong to assume because the current is going one way through the primary it must be going the same way through the secondary. Actually the DC component is lost and the AC is passed, so I just get squint AC.

Or should learn more. Spice is a good tool for things like this. As Mike E says, the main function of LT Spice is to train your instincts.

The penny drops.

Trying to make a high voltage DC supply? You can get 1KV 1 amp diodes for a few cents each. Those can be used in series.

When I was a kid, I used old neon sign transformers and 1B3 rectifier tubes to make high voltage DC supplies. I couldn't afford a Variac so adjusted the filament voltage to regulate the output voltage. I used a D-cell battery and a rheostat, and somehow I'm still alive.

Digikey has a 16 KV diode for 33 cents.

Not totally. IIRC correctly the current in the secondary is 'backwards'; on terms of its ability to generate back EMF.

Furthermore the impedance of the transformer to rectified AC with a DC component will now be so low that the primary will burn out.

You should generally be careful doing that. If one is leaky it will put a far higher voltage across the others. In general you need to select for reverse leakage current OR put high value resistsiors across them to guarantee a predictable 'leakiness'

Modern diodes are almost all controlled-avalanche. They zener without a negative-resistance snap effect, so are safe to run in series; they self-adjust. Silicon HV diodes are a stack of lower-voltage junctions.

You can Spice a series string of various-voltage zeners and see what happens.

Two items of folk wisdom "don't put diodes in series" and "don't put diodes in parallel" are mostly wrong.

The first company I worked for made dielectric preheaters for the plastics industry. The were basically a 7.5 kW oscillator with the material placed in the RF cavity. There rolled their own high voltage rectifiers and capacitors. I forget how many diodes were in series with the whole assembly potted into a brick with two lugs.

They operated in the FM band but the frequency change as the material heated was minimal unlike the RF heat sealers that were known for their whoosh sounding interference.

On the factory floor both were rumored to make you sterile or incredibly fertile, take your pick. In the days before microwave ovens were common the the workers also figured out the preheaters were handy for warming up you sandwich.

The same company did make several industrial sized microwave ovens for restaurants but completely missed the potential of the consumer market.

That isn't generally an issue. It is inherent they will conduct a small current, but that will naturally equalise as they get close to their breakdown voltage.

In life and reality things are not so black and white. Those prophesies are reserved most appropriately for colour blind art students.

If you were able to use a simulation tool like LT Spice, you would understand that the problem isn't nearly as severe as you might think. The back emf from the transformer would continue the sinusoidal waveform well beyond the crossing point.

Mr Kingsey, if so inclined and capable, could measure the resistance of his transformer and measure the average DC current into his circuit to confirm.

I would expect for a standard transformer, for the average (DC) current to be 1/10 of the resistance alone. BICBW

F*ck off you pompous ass. It's fun to play with things you don't understand.

You seem to an awful lot of playing with things you don't understand.

No idea what you mean by dots.

Dots are little round filled circles. They indicate winding polarity.

If you think you understand everything, there's nothing to learn.

The smart ones do their research first before asking the sorts of questions I was asking when I was 8.

Otherwise you are indeed correct. There is a saying, the more you know, the more you realise you don't know.

Now if Mr Kinsey asked a question about LTSpice I would be far more impressed.