On Monday, September 30, 2019 at 11:27:01 PM UTC+10, Bill Sloman wrote:> On Monday, September 30, 2019 at 6:45:49 PM UTC+10, Winfield Hill wrote: > > We need a 25kV rms AC signal. OK, that's 70kV p-p. > > > > I had a 30kV Trek model 678 amplifier, a huge beast > > procured on eBay, but I fear it was thrown away in > > a downsizing move, damn! With that we could make a > > 10kV rms AC signal, at a frequency of our choice. > > And maybe transform it up to 25kV. > > > > Years ago I made RIS-333 / RIS-470, a 10kV 600kHz > > amplifier / resonant-transformer for a mass spec. > > That was 10kV amplitude, or 20kV p-p. RIS-480 / > > RIS-514 was a compact 7.5kV 300kHz version. But now > > we need more voltage, and at much lower frequencies. > > > > A company, Transzvill, in Budapest, sells the FM-24. > > It's a huge 300x363mm AC-line transformer, rated at > > 24kV 400VA. I think it's molded, rather than oil- > > filled. OK, at least it's not a pole-pig. But, > > haha, we only need 10uA of current, so something > > much smaller would be nice. > > > > 50 or 60Hz are probably good frequencies for us, > > although it'd be nice to experiment with a little > > bit higher, maybe 400Hz. Hmm, many 60Hz power > > transformer are happy at 400Hz. Use a class-D > > amplifier to drive a 50-to-230V step-up xformer, > > then on to a 25kV transformer beast someplace. > > My thought would be an extended ferrite core - made up of perhaps two of these sets, with the two U-sections separated by the two I-sections - to make a toroid with enough space in the middle to make room for a useful number of turns of 25kV-capable cable. > > http://www.farnell.com/datasheets/2138476.pdf > > You could extend it further with more I-sections > > http://www.farnell.com/datasheets/1595819.pdf > > None of them are cheap. > > 25kV for 5msec is a lot of volt-seconds. Even with gaps, you might end up needing a very long path through the ferrite to avoid saturation. > > It might give you a way of setting up Piotr Wyderski's array of lots of transformers with enough room for cables that wouldn't arc through.There's nothing like sleeping on a problem to drag out the other half of the solution. The high voltage windings would pancake wound, as stack of printed circuit boards. Each board would be about 120mm long by about 60mm wide, and would have two square holes about 29mmx30mm to accommodate the (almost square) legs of the extended core. Each board would have - say - 500 turns (250 around each leg) which (at around 1turn per volt) would develop about 500V. There would be fifty of them to generate your 25kV. You'd connect each board to the next with strip of berylium copper. For 1.6mm thick boards, the spacing between board would be about 5mm when you were soldering on the strip. You then flip the first board onto the second, solder on another Be/Cu strip, and add the next, Z-stacking them until you have your fifty. Then thread the ferrite cores through the stack - which is going to end up 80mm high (so two of the U-cores would give you enough winding space). The energising/driver winding is left as an exercise for the reader. The whole thing would go into a metal box with two 25kV coax sockets sticking out either side, and you'd fill it up with transformer oil or perhaps a high-voltage soft potting compound. An obvious variant would be to use a pair of C-cores to make a toroid, feeding a similar z-stack of boards (with only one central hole) to create the high voltage winding. -- Bill Sloman, Sydney
25kV AC
Started by ●September 30, 2019
Reply by ●September 30, 20192019-09-30
Reply by ●September 30, 20192019-09-30
Tauno Voipio wrote...> >On 30.9.19 18:17, Winfield Hill wrote: >> >> We use a nice 4.8mm dia wire, AWM 3239, with >> a 40kV rating, CSA TV-40. Judd Flexrad HV. > > > Please be careful with radii of wire ends and > terminations, so that your kilovolts won't > sizzle into thin air as corona.I use spherical hadware-store fishing weights. -- Thanks, - Win
Reply by ●September 30, 20192019-09-30
Winfield Hill <winfieldhill@yahoo.com> wrote in news:qmsl0t02ual@drn.newsguy.com:> DecadentLinuxUserNumeroUno@decadence.org wrote... >> >>Winfield Hill <winfieldhill@yahoo.com> wrote in >>news:qmsfbm02m7s@drn.newsguy.com: >> >>> We need a 25kV rms AC signal. OK, that's 70kV p-p. >> >><https://www.advancedenergy.com/products/high-voltage-power-supplie >>s/> > > Yep, nice stuff, lots of stuff, but all DC not AC. > >Dag nabbit! Did my old eyes miss that itty bitty tid bit? :-) Sorry 'bout that. Yes, a neon sign xformer should do it. If you want, you can isolate it (read insulate: lucite box) and use a higher input voltage on it to get where you need to be. Or insulate both from ground and step up into it. IOW I am saying it can handle the higher voltage, one just has to be mindful of any exposed nodes, which I am sure you already know about. Another source might be looking into a couple popular Tesla coiler forums. They often have AC gear sources.
Reply by ●September 30, 20192019-09-30
Winfield Hill <winfieldhill@yahoo.com> wrote in news:qmsl3202udc@drn.newsguy.com:> Piotr Wyderski wrote... >> >>Winfield Hill wrote: >> >>> We need a 25kV rms AC signal. OK, that's 70kV p-p. >> >> ~100 small 230V/12V transformers with primaries connected >> in series should do the job. This is 10x10 grid of them, >> doable and reasonably compact. > > Whoa!! Huge arcs from secondary to primary > destroys the transformers, sorry. >Not really. As long as they are all isolated from each other, the primary to secondary voltage differential will be the same. Xfmr #10 simply cannot be allowed to be proximal to Xfmr #1 Actually, one wants full isolation of all of them from any of their bretheren. Then, there will be no arcs. Take a 2:1 for starts. # 1 120 in 240 out Pri to Sec separation: 120 Volts # 2 240 in 480 out Pri to Sec separation: 240 Volts # 3 480 in 960 out Pri to Sec separation: 480 Volts # 4 960 in 1920 out Pri to Sec separation: 960 Volts This is where I would start to worry about winding to winding arcing (in air). So, immerse remaining set in fluorinert dielectric fluid or xfmr oil. # 5 1920 in 3840 out Pri to Sec separation: 1920 Volts # 6 3840 in 7680 out Pri to Sec separation: 3840 Volts Possible arcing: # 7 7680 in 15360 out Pri to Sec separation: 7680 Volts # 8 15360 in 30720 out Pri to Sec separation: 15360 Volts Definite arcing potential even in the oil or fluorinert # 9 30720 in 61440 out Pri to Sec separation: 30720 Volts #10 in out Pri to Sec separation: Volts Transformers can be made with increased primary to secondary isolation capacity, but then efficiency will start to suffer at some point. Yeah, this is not a good method...
Reply by ●September 30, 20192019-09-30
bloggs.fredbloggs.fred@gmail.com wrote...> > On September 30, 2019, Winfield Hill wrote: >> >> We need a 25kV rms AC signal. OK, that's 70kV p-p. > > What exactly is your output waveform? It sounds like > a 70kVpp of 5-10ms pulses at 60-400Hz rep rate.The industry standard is 50Hz sine wave, often 24kV rms. -- Thanks, - Win
Reply by ●September 30, 20192019-09-30
Wond <lost@the.ether.net> wrote in news:qmt6rt$j4j$1@dont-email.me:> On Mon, 30 Sep 2019 01:45:42 -0700, Winfield Hill wrote: > >> We need a 25kV rms AC signal. OK, that's 70kV p-p. >> >> I had a 30kV Trek model 678 amplifier, a huge beast procured on >> eBay, but I fear it was thrown away in a downsizing move, damn! >> With that we could make a 10kV rms AC signal, at a frequency of >> our choice. And maybe transform it up to 25kV. >> >> Years ago I made RIS-333 / RIS-470, a 10kV 600kHz amplifier / >> resonant-transformer for a mass spec. That was 10kV amplitude, >> or 20kV p-p. RIS-480 / RIS-514 was a compact 7.5kV 300kHz >> version. But now we need more voltage, and at much lower >> frequencies. >> >> A company, Transzvill, in Budapest, sells the FM-24. >> It's a huge 300x363mm AC-line transformer, rated at 24kV 400VA. >> I think it's molded, rather than oil- filled. OK, at least it's >> not a pole-pig. But, haha, we only need 10uA of current, so >> something much smaller would be nice. >> >> 50 or 60Hz are probably good frequencies for us, although it'd >> be nice to experiment with a little bit higher, maybe 400Hz. >> Hmm, many 60Hz power transformer are happy at 400Hz. Use a >> class-D amplifier to drive a 50-to-230V step-up xformer, then on >> to a 25kV transformer beast someplace. >> >> I have all types of small high-voltage pulsers / transformers, >> many from Alibaba, for electrostatic precipitators, etc. Some >> are sold simply to make sparks, but these are short-duration >> pulse types, and we need 2-10ms pulses, too long. TV flyback, >> 15kHz, nah. Also, Tesla-coil types need not apply. >> >> Ah, maybe a neon-sign transformer of some type. Hmm, only 10 to >> 15kV. And most are big and bulky. > > The old oil-furnace ignition transformers would initiate and > sustain > an arc about an inch and a half long, in air. Dunno what voltage. >They are like 25kV @ 1mA. But any loading, even the 1mA drops (clamps) it way down. Cause I hit myself with one way back in the '70s when I used one for a jacobs ladder. Then I touched it. Once. Good thing I am still here.
Reply by ●September 30, 20192019-09-30
On Monday, September 30, 2019 at 8:19:53 PM UTC-4, Winfield Hill wrote:> The industry standard is 50Hz sine wave, often 24kV rms.50Hz in a 60Hz country? Then they have to generate it. How do they do that? Learn how, then you can do the same.> Thanks, > - Win
Reply by ●September 30, 20192019-09-30
Steve Wilson wrote...> >On Monday, September 30, 2019 at 8:19:53 PM UTC-4, Winfield Hill wrote: > >> The industry standard is 50Hz sine wave, often 24kV rms. > > 50Hz in a 60Hz country? Then they have to generate it. > How do they do that? Learn how, then you can do the same.The papers I've come across are all in the EU. But 60Hz is really an equivalent. I suppose the issue is how long the "zero-crossing" time is, when the voltage has dropped below an effective value. Somehow the electrospinning thread doesn't break, and when the voltage returns, a new thread starts. Soon there are many simultaneous threads. -- Thanks, - Win
Reply by ●September 30, 20192019-09-30
On 30 Sep 2019 01:45:42 -0700, Winfield Hill <winfieldhill@yahoo.com> wrote:> We need a 25kV rms AC signal. OK, that's 70kV p-p. > > I had a 30kV Trek model 678 amplifier, a huge beast > procured on eBay, but I fear it was thrown away in > a downsizing move, damn! With that we could make a > 10kV rms AC signal, at a frequency of our choice. > And maybe transform it up to 25kV. > > Years ago I made RIS-333 / RIS-470, a 10kV 600kHz > amplifier / resonant-transformer for a mass spec. > That was 10kV amplitude, or 20kV p-p. RIS-480 / > RIS-514 was a compact 7.5kV 300kHz version. But now > we need more voltage, and at much lower frequencies. > > A company, Transzvill, in Budapest, sells the FM-24. > It's a huge 300x363mm AC-line transformer, rated at > 24kV 400VA. I think it's molded, rather than oil- > filled. OK, at least it's not a pole-pig. But, > haha, we only need 10uA of current, so something > much smaller would be nice. > > 50 or 60Hz are probably good frequencies for us, > although it'd be nice to experiment with a little > bit higher, maybe 400Hz. Hmm, many 60Hz power > transformer are happy at 400Hz. Use a class-D > amplifier to drive a 50-to-230V step-up xformer, > then on to a 25kV transformer beast someplace. > > I have all types of small high-voltage pulsers / > transformers, many from Alibaba, for electrostatic > precipitators, etc. Some are sold simply to make > sparks, but these are short-duration pulse types, > and we need 2-10ms pulses, too long. TV flyback, > 15kHz, nah. Also, Tesla-coil types need not apply. > > Ah, maybe a neon-sign transformer of some type. > Hmm, only 10 to 15kV. And most are big and bulky.Used old portable 60hz X-Ray unit? Take the tube and rectifier out and you have a 100kv transformer with 120vac input. Cheers
Reply by ●September 30, 20192019-09-30
Martin Riddle <martin_ridd@verizon.net> wrote in news:5ga5ped2ntd8jqondg6umr64smqtg5gij3@4ax.com:> On 30 Sep 2019 01:45:42 -0700, Winfield Hill > <winfieldhill@yahoo.com> wrote: > >> We need a 25kV rms AC signal. OK, that's 70kV p-p. >> >> I had a 30kV Trek model 678 amplifier, a huge beast >> procured on eBay, but I fear it was thrown away in >> a downsizing move, damn! With that we could make a >> 10kV rms AC signal, at a frequency of our choice. >> And maybe transform it up to 25kV. >> >> Years ago I made RIS-333 / RIS-470, a 10kV 600kHz >> amplifier / resonant-transformer for a mass spec. >> That was 10kV amplitude, or 20kV p-p. RIS-480 / >> RIS-514 was a compact 7.5kV 300kHz version. But now >> we need more voltage, and at much lower frequencies. >> >> A company, Transzvill, in Budapest, sells the FM-24. >> It's a huge 300x363mm AC-line transformer, rated at >> 24kV 400VA. I think it's molded, rather than oil- >> filled. OK, at least it's not a pole-pig. But, >> haha, we only need 10uA of current, so something >> much smaller would be nice. >> >> 50 or 60Hz are probably good frequencies for us, >> although it'd be nice to experiment with a little >> bit higher, maybe 400Hz. Hmm, many 60Hz power >> transformer are happy at 400Hz. Use a class-D >> amplifier to drive a 50-to-230V step-up xformer, >> then on to a 25kV transformer beast someplace. >> >> I have all types of small high-voltage pulsers / >> transformers, many from Alibaba, for electrostatic >> precipitators, etc. Some are sold simply to make >> sparks, but these are short-duration pulse types, >> and we need 2-10ms pulses, too long. TV flyback, >> 15kHz, nah. Also, Tesla-coil types need not apply. >> >> Ah, maybe a neon-sign transformer of some type. >> Hmm, only 10 to 15kV. And most are big and bulky. > > Used old portable 60hz X-Ray unit? Take the tube and rectifier out > and you have a 100kv transformer with 120vac input. > > Cheers >Old ECG airport X-ray unit has dual 40kV units if one follows your same instructions (remove multipliers). The voltage multiplier units alone are worth some bucks.
