HV school project

[danielsmusic]

my teacher at school wanted the class to desine a circuit that uses a 555 timer, so the first thing i said was smoke bomb. but he said it has to ocilate. so i thought jacobs ladder. if it ocillates at 50Hz and feed 4 transformers out of wall warts backwards, i will have a very high voltage.

any comments, suggestions.

ps: i don't want to use a neon sign transformer or a tv flyback.

 

[audioguru]

When you connect step-up transformers so the 2nd one steps-up the output of the 1st one, then the 2nd one is such a heavy load on the 1st one that they don't work.

To make a high voltage you need a transformer that is designed for it. It also needs to have special high voltage insulation that isn't in a wall-wart.

If you connect a transformer backwards to the mains, you won't get the mains voltage stepped-up, you'll get smoke and maybe a fire.

 

[Nigel Goodwin]

You also don't have a prayer that such a project would be acceptable in school 8)

 

[danielsmusic]

i have done this before i worked ok for me.

school don't care, i have a teacher that will let me do almost anything

 

[Someone Electro]

But at abut 2kV the secundary will start to arc.

You need an TV flyback or an neon transformer.

 

[danielsmusic]

i do have a tv flyback transformer but don't know how to use it. it sould generate 35kv.

 

[danielsmusic]

what about a massif inductor

 

[Someone Electro]

In the old days they used inductors but you wod need afuly a lot of wire.

Flyback transformers work at ultrasonic freq.(more then 20KHz)You need an transistor to drive it.

Anyway i never made an jacobs lader.

 

[danielsmusic]

how do i get 20Kh i can't think of a power transistor that can switch that fast?

 

[Optikon]

i have done this before i worked ok for me.

school don't care, i have a teacher that will let me do almost anything

That teacher is not very responsible.

 

[Optikon]

how do i get 20Kh i can't think of a power transistor that can switch that fast?

That's not hard to do. You'll pick your transistor based mostly on the operating specs like current and voltage it will need to withstand. probably, the last thing to do is design the driver to get it to switch as fast as you need it.

 

[Nigel Goodwin]

i have done this before i worked ok for me.

school don't care, i have a teacher that will let me do almost anything

You won't have him for long then! - a teacher so irresponsible will soon be sacked!, he's leaving the school wide open for massive law suits by his incompetence.

 

[danielsmusic]

well, i don't mean like that. he's a nice guy, stics to the rules but i think i am pushing. there are alot of teachers like that in our school even the deputy head. but the exam grades are almost perfect, in drama last years gcse class all got a C or above and in science somone got 100% on a test!

 

[zachtheterrible]

You could use the 555 to drive the flyback tranformer from 12v. I think that's the input to them?

You will probably have to find a really old flyback transformer because the new ones have a protection diode built into them that is impossible to remove and makes it hard to make a jacobs ladder. The older ones diode is really easy to remove.

 

[danielsmusic]

what makes it so hard?

 

[audioguru]

Daniels, in England older TV flyback transformers operated at a lower frequency. The transformer might be tuned to its operating frequency. Use the same parts that the TV had.

 

[danielsmusic]

well it wasn't a tv it was a old monitor. what parts do i start with, there are names i have never heard before.

 

[danielsmusic]

is there a way of dubbling current without affecting voltage?

i mean, i have 50v at 500ma and a 12v at 100A it there a way to use the 12 supply to duble the current of the 50v supply.

 

[audioguru]

You have 12V at 100A? From a car battery?
Use a DC to DC inverter circuit to step it up to 50V at nearly 24A.
The battery charge won't last more than about 1 to 2 hours.

 

[jrz126]

what about the ignition coil from a car? (for the old distributor style ignitions). I saw this project in a magazine and thats what they used.

Over here in the states, a quick trip to autozone and you can have a new one for $10-$12