Recently on various YouTube electronics channels, I saw projects where a cheapo ($3) EBAY boost converter was used. It can take a 3.6V-6V DC input and boost to 400kV in a small package. I'm interested in how these are designed inside. I have basic/intermediate electronic knowledge. Does anyone know of a schematic for this or similar? I appreciate the feedback. Thanks!

 

I was also wondering about that, and I found a kit on ebay which is supposed to do the same thing but I can not figure out how it would work. Here is the supplied schematic.

A.H.W.

 

Hey, thanks for the response! Did this schematic come with the kit? That's a pretty suspect looking schematic if we can call it one :/
Maybe some others can chime in and we can figure something out. Best!
Tony

 

It has no chance of doing anything useful that I can see.

 

I know the easy way is to order one and tear it apart and analyze it, but in all honesty I don't really order off of EBAY for electronics. I'm fortunate enough to have a OEM parts supplier here in town for mad scientist types, lol.

 

It is a blocking oscillator like this one, but without the LED and with a secondary on L1.


It should go without saying but never touch the output and never touch the output to anybody.

 

It is a blocking oscillator like this one, but without the LED and with a secondary on L1.
View attachment 123733

It should go without saying but never touch the output and never touch the output to anybody.

Thanks.
A.H.W.

 

It is a blocking oscillator like this one, but without the LED and with a secondary on L1.
View attachment 123733
It should go without saying but never touch the output and never touch the output to anybody.

Ok, fantastic! No worries with the safety issues. I'm a bit overboard at times in that department : ) .....I'll have to give this a go. Be interested to see what other responses come up- achieving the same goal. Much appreciated!

Moderator's note: When replying with a quote, be careful to add your text outside the quoted area. -dc

 

Recently on various YouTube electronics channels, I saw projects where a cheapo ($3) EBAY boost converter was used. It can take a 3.6V-6V DC input and boost to 400kV in a small package. I'm interested in how these are designed inside. I have basic/intermediate electronic knowledge. Does anyone know of a schematic for this or similar? I appreciate the feedback. Thanks!

An idea that misses your target by a fair bit - but may be instructive:-

The horizontal output section of a B&W portable TV takes 12V and the flyback EHT gives you somewhere around 6 - 12kV. You can get it up to 400kV with a long enough Cockroft-Walton multiplier, but you won't get much current and it won't be a small module.

Another complication is that in the TV; the scan coils inductance is part of the resonant system that generates large flyback pulses - you'll have to mess about with high voltage capacitors to re tune the flyback transformer.

I've made several flyback converters by using a small SMPSU transformer backwards to get about 400V from a 4.8V Ni-Cd pack, which is much simpler than what it takes with a TV flyback section - but you'd need a much longer diode/capacitor voltage multiplier.

 

An idea that misses your target by a fair bit - but may be instructive:-

The horizontal output section of a B&W portable TV takes 12V and the flyback EHT gives you somewhere around 6 - 12kV. You can get it up to 400kV with a long enough Cockroft-Walton multiplier, but you won't get much current and it won't be a small module.

Another complication is that in the TV; the scan coils inductance is part of the resonant system that generates large flyback pulses - you'll have to mess about with high voltage capacitors to re tune the flyback transformer.

I've made several flyback converters by using a small SMPSU transformer backwards to get about 400V from a 4.8V Ni-Cd pack, which is much simpler than what it takes with a TV flyback section - but you'd need a much longer diode/capacitor voltage multiplier.

I like the idea and seems like a fun project for the future if I can get a hold of a old TV on the cheap somewhere. For now I'm just looking to build something simplistic with components I can get low cost here. DickCappels schematic looks very doable in that regard.

 

I like the idea and seems like a fun project for the future if I can get a hold of a old TV on the cheap somewhere. For now I'm just looking to build something simplistic with components I can get low cost here. DickCappels schematic looks very doable in that regard.

Car ignition coils are popular, but you probably need CDI to get 40kV - and it won't work so well with a multiplier.

 

Recently on various YouTube electronics channels, I saw projects where a cheapo ($3) EBAY boost converter was used. It can take a 3.6V-6V DC input and boost to 400kV in a small package.

I'd have serious doubts about their claim of 400 KV. 400KV in open air will jump an open air gap of about 6 inches across and its not something that can be done with cheap low power components running off a low voltage battery source.

I used to play with HV years ago and I did experiments with modified flyback transformers from old TVs. The biggest ones I had were for old 28 - 32" CRT units and even with extreme overdriving getting one up to around 100KV outputs was hard. The coronal discharge effects on the secondaries at that degree of overdriven power was uncontrollable crazy. They would get so hot from the coronal discharge at that voltage that if ran for very long the insulation would start smoking then arc over internally and destroy them.

Given that problem to get any higher of voltages I had to start making full Tesla coil systems. With those getting to the 500KV to 1 MV+ voltage ranges was rather easy but still not something that was doable from a low DC power source. Most of my stuff ran off multi hundred watt 10 - 15 KV 30 - 60 milliamp neon sign transformers to get there.

 

I'd have serious doubts about their claim of 400 KV. 400KV in open air will jump an open air gap of about 6 inches across and its not something that can be done with cheap low power components running off a low voltage battery source.

.

At TV horizontal frequency - 400kV will jump a room.