These Weird DC Step Up Converters?!?!? - Page 1
Forum section: electronics / beginners

author: ThaWookiees
author_rank: Newbie
timestamp: August 08, 2015, 04:05:54 pm
content: Hello, I am somewhat new to electronics engineering and I need a high voltage power supply 1-10 kv dc for vacuum applications.I understand how an AC transformer works, but these DC transformers I see on Amazon and Ebay are intriguing. Do they work, or are they just a bunch of BS potted wires? I can't just get a high voltage supply, because of the high cost, and a mains ac to high voltage ac to high voltage dc may not work as well as my dc supply to high voltage dc because of its complexity and my lack of soldering skill. I will be building a magnetron for sputtering that uses high V DC, but I also want to do plasma induction cleaning. I have seem some people do it with radio frequency (Mhz range) ac transmitters and radio frequency tuners, but again, this will be too expensive. Can I just use DC? I have heard induction coils must receive AC or pulsed dc, can I use an oscillator and the high voltage DC for that? Or would it be better to just hack a microwave oven transformer to get a high v AC supply? Also, I don't care too much about power, as I have all the time in the world, but in case you want to give me specific componentsmy project may reach 50-500 watts.Thanks for your input!

author: Zero999
author_rank: Super Contributor
timestamp: August 08, 2015, 04:31:24 pm
content: It's not a DC transformer. The DC voltage is converted to AC and boosted by a transformer.It's very unlikely it'll output the 400kV claimed and mustn't be operated open circuit, otherwise the insulation will arc over.I doubt this little power supply will be able to provide more than 10W.

author: SeanB
author_rank: Super Contributor
timestamp: August 08, 2015, 04:37:29 pm
content: Those are the ignitors for gas boilers, sold as HV generators. They are able to supply at best enough voltage to trigger an arc across a 5mm gap to fire a gas boiler, and are not designed for operation for longer than a minute at a time. You will not have any joy with those in your application, you will need a power supply with a higher current power supply.

author: new299
author_rank: Regular Contributor
timestamp: August 08, 2015, 05:14:54 pm
content: Quote from: ThaWookiees on August 08, 2015, 04:05:54 pmIf I've understood correctly... You can use DC for sputtering conductive material, I think Ben Krasnow used a DC supply at one point. To sputter insulators you need RF Magnetron sputtering. That's my understanding anyway.

author: Isad
author_rank: Frequent Contributor
timestamp: August 08, 2015, 06:58:51 pm
content: What about a zvs+flyback transformer from a tv will do for 1-10kvtho idk if it can supply 500W u will really need to go bigger or go homefor the driver mosfets.

author: ThaWookiees
author_rank: Newbie
timestamp: August 08, 2015, 09:39:35 pm
content: Okay, so in short, no I can't do this so easily. I think I may be willing to go AC to high V AC to high V DC. From my understanding I plug mains into a high Henry transformer then put in a diode to rectify the current? After writing that sentence I have once again become scared, and am looking back to the gas boiler igniters (you sir, are a genius), and am wondering if they'll work if I use a big enough heat sink. I have machining capabilities at home (well, there's a lot I can do with my drill press), and if the heat sink is too hard to machine, I can 3d model one and have Shapeways print it for me. Heck it would still be cheaper than a used high voltage power supply from ebay!So, can I heat sink and water cool the boiler igniters? Or would hacking the microwave with a diode be best? Also, what's the best diode for my application? I know a zener would probably explode at this voltage

author: Ian.M
author_rank: Super Contributor
timestamp: August 08, 2015, 11:12:58 pm
content: Find a large old multisync CRT monitor for which a circuit diagram is available. Clone the EHT section reusing the transformer, with integrated tripler (rectifier) and its high voltage switching transistor. Control the EHT voltage by varying the feed voltage to the transformer. Should be good for about 3mA depending on the tube size, at up to 15KV. N.B. keep the low voltage supply to the control circuit fixed.Why NOT use a TV EHT circuit? The line output transformer is closely coupled to the line scan coils on the yoke and if you dont keep them connected its highly likely to blow the line output transistor. Because a multisync monitor has to handle many different scan rates they usually have seperate line scan and EHT circuits.

author: amyk
author_rank: Super Contributor
timestamp: August 09, 2015, 12:07:21 pm
content: 400kV would be enough to arc ~13cm, definitely beyond the abilities of these tiny supplies. 40kV is more like it.