Help me understand cheap boost module?

[mishima]

TL;DR Summary

It's a transformer. I'd like more detail, or help reverse engineering a circuit diagram.

Hi, I recently acquired some of these cheap modules for plasma experiments. I tried dissolving the epoxy off of one of them in an attempt to reverse engineer the circuit. I can see a resistor, diode, and transformer but am unsure about some of the other components. I was wondering if anyone here could just look at some of these parts and help identify them, or give some insight into what is going on with the circuit.

Also a question, with these boost modules I notice a magnetic attraction in the chains that I don't experience with the neon sign transformer. Why?

 

[berkeman]

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[berkeman]

Thread is reopened provisionally...

Hi, I recently acquired some of these cheap modules for plasma experiments.

What kind of "plasma experiments" are you planning on doing? Why do you need 400kV? What experience do you have working with high voltages?

From the info in your link at Amazon:

★High pressure type: the type of pulse current.Output voltage: 400000 v (Please pay attention to safety).
★High pressure discharge distance between: 10 mm - 20 mm.

 

[mishima]

It is a Jacob's ladder that uses 2 hanging chains as the conductors, and also this. For the latter I have not had much luck getting my 3d prints to become conductive enough. But it makes a great Jacob's ladder with a 6V lantern battery and some hanging chains.

I have used neon sign transformers in the past for similar Jacob's ladders, and I never noticed the magnetic attraction between the chains the way these smaller modules create. I assume the pulse current design in these things is causing the effect. I was hoping to get some rough idea of a circuit diagram from taking one apart.

edit: I don't believe they are actually that high of a voltage, but I also don't have a great way to measure it. That is another reason why I'd like to work out a schematic. As for my experience, not a lot. I have a physics degree and have been teaching physics for a decade and some change. I believe I am taking all the precautions necessary to mitigate the risk. I am not an electronics engineer however.

 

[Guineafowl]

As I understand it, a handheld taser has two ‘stabbing’ prongs for delivering the shock, branching off from which are two smaller prongs closer together.

When the unit is activated, but not applied to a baddie, the arc is allowed to jump across the smaller prongs. This snapping arc acts as a deterrent, but also prevents the unit from operating open circuit, which quickly destroys the windings by internal arcing.

Also, would the pulsed arc from these suit a Jacob’s ladder? The arc normally takes a second or two to climb up, but the pulsed arc from these units would keep breaking.

 

[mishima]

Yes, it works similar to a Jacob's ladder but the climbing effect is not as smooth, as you say. It does clearly rise in height. Also as mentioned, there is a magnetic attraction effect I never noticed with other transformers.

It's interesting because the magnetic effect actually pulls the chains together before any arc, so it kind of auto-adjusts the gap spacing (which otherwise takes some tinkering with the traditional neon sign transformer).

 

[DaveE]

It is a Jacob's ladder that uses 2 hanging chains as the conductors, and also this. For the latter I have not had much luck getting my 3d prints to become conductive enough. But it makes a great Jacob's ladder with a 6V lantern battery and some hanging chains.

I have used neon sign transformers in the past for similar Jacob's ladders, and I never noticed the magnetic attraction between the chains the way these smaller modules create. I assume the pulse current design in these things is causing the effect. I was hoping to get some rough idea of a circuit diagram from taking one apart.

edit: I don't believe they are actually that high of a voltage, but I also don't have a great way to measure it. That is another reason why I'd like to work out a schematic. As for my experience, not a lot. I have a physics degree and have been teaching physics for a decade and some change. I believe I am taking all the precautions necessary to mitigate the risk. I am not an electronics engineer however.

You'll need to be a d#$@ sight more careful around HV than that guy in the video. YouTube is an awful place to learn about potentially dangerous activities.

Switch mode power supplies are relatively complex things for someone that hasn't studied EE. It won't actually help you much to see what's in that circuit, you won't know what your looking at. You probably don't have the equipment necessary to build one that works. They typically just don't work if you put together a bunch of parts without really understanding the theoretical basis. This is good news because it limits how much danger you'll be exposed to, unlike neon sign transformers, for example.

BTW 400kV is ridiculous. That is not a trustworthy source, they are lying to you, and assuming you know nothing about HV power supplies. Maybe the engineering is good, IDK. But the marketing is disingenuous.

 

[mishima]

Oh, I am not trying to build my own power supply. I was just trying to get a circuit diagram of this one to study, mostly in an effort to explain it better to curious students and differentiate it from the neon sign transformer. As I said, my current explanation amounts to 'its a transformer, a transformer is...(normal textbook explanation with algebra based math)' which I feel is lacking.

I don't base my safety practices on YouTube videos. I've had some university circuit labs and worked with some high voltage circuits as a service observer at a USGS telescope. And no, indeed I don't have a degree in EE (I wish) but I can usually make sense of schematics after a little study and simulation...and coffee and help from physics forums. ;)

 

[mishima]

So, these are possibly switch mode power supplies? Is anything identifiable from the pictures? I can try to remove more epoxy, but its a little fragile.

 

[Rive]

So, these are possibly switch mode power supplies?

I would not call them that. Just some kind of self-oscillating boost circuit without any regulation or filtering.

If you terminate the current on a coil fast enough you can make some really high voltages without any need to have serious HV circuitry.
Example.


BTW the same black tube-like thing is advertised everywhere with outputs from 50kV to 1MV.
Dangerous, stupid joke.