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.
25kV AC
Started by ●September 30, 2019
Reply by ●September 30, 20192019-09-30
Reply by ●September 30, 20192019-09-30
jlarkin@highlandsniptechnology.com wrote...> > Win, can you use differential drive into your gadget? > Maybe a full-bridge with the uppers just constant-current, > so the lower grids are near ground.I'd go with a 35kV full-bridge, with each leg using 35 1.2kV MOSFETs in series, with a 4x.26-type gate divider. I'm using IXTY02N120P, low-capacitance DPak parts, with a 70-piece minimum order, I just received 140 of them. Machine assembly. Nah, just buy a big transformer! -- Thanks, - Win
Reply by ●September 30, 20192019-09-30
On 30.9.19 18:17, Winfield Hill wrote:> Tauno Voipio wrote... >> >> The tens of kilovolts need careful attention to electric >> field strength. The wires and terminals need to pretty >> bulky to keep the field strength under control. > > Yes indeed. 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. -- -TV
Reply by ●September 30, 20192019-09-30
Wond wrote...> > The old oil-furnace ignition transformers would initiate > and sustain an arc about an inch and a half long, in air. > Dunno what voltage.Yes, interesting, and much smaller. Probably too low a voltage. Also, we need hours of continuous operation. -- Thanks, - Win
Reply by ●September 30, 20192019-09-30
On 2019/09/30 8:26 a.m., Wond wrote:> 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. >Formula for spark gap KV in air: http://www.kronjaeger.com/hv/hv/msr/spk/ John :-#)#
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.To summarize the requirement, Do you want a sine wave or a pulse? What waveform/polarity/coupling? Single ended or differential? Load? Cable? Rep rate/duty cycle? -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●September 30, 20192019-09-30
On Mon, 30 Sep 2019 08:56:56 -0700, John Robertson wrote:> On 2019/09/30 8:26 a.m., Wond wrote: >> 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. >> >> > Formula for spark gap KV in air: > > http://www.kronjaeger.com/hv/hv/msr/spk/ > > John :-#)#Nice, thanks. Looks 40kV-ish.
Reply by ●September 30, 20192019-09-30
mandag den 30. september 2019 kl. 12.22.07 UTC+2 skrev Winfield Hill:> Steve Wilson wrote... > > > >On Monday, September 30, 2019 at 4:45:49 AM UTC-4, Winfield Hill wrote: > >> We need a 25kV rms AC signal. OK, that's 70kV p-p.=20 > > > >> Ah, maybe a neon-sign transformer of some type. > >> Hmm, only 10 to 15kV. And most are big and bulky. > > > > Try the ignition coil from a 4 cylinder wasted spark engine. ... > > > > So if you can use pulses instead of a sine wave, this may > > be your ticket. > > Thanks, but they'd need to be able to make 5ms pulses, > that's ms, not us.drive it with a few hundred V AC? they usually have a ratio around 1:100
Reply by ●September 30, 20192019-09-30
On Monday, September 30, 2019 at 4:45:49 AM UTC-4, 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. > > > -- > Thanks, > - WinWhat exactly is your output waveform? It sounds like a 70kVpp of 5-10ms pulses at 60-400Hz rep rate.
Reply by ●September 30, 20192019-09-30
Winfield Hill wrote:> Jeroen Belleman wrote... >> >> Winfield Hill wrote: >>> DecadentLinuxUserNumeroUno@decadence.org wrote... >>>> Winfield Hill <winfieldhill@yahoo.com> wrote: >>>> >>>>> We need a 25kV rms AC signal. OK, that's 70kV p-p. >>>> <https://www.advancedenergy.com/products/high-voltage-power-supplies/> >>> >>> Yep, nice stuff, lots of stuff, but all DC not AC. >> >> Win, I don't see how you can expect to get by with 10uA. >> Parasitic capacitances alone will take more than that! >> >> What's this for? > > This is for AC-driven electrospinning. OK, at 60Hz, > with 100pF wiring, the AC load is j26 M-ohms, making > an AC current of about 1mA. At 400Hz it'd be 6.3mA, > consuming 157 watts if in phase. OK, that's a point. > Maybe a 400VA transformer isn't overkill after all. > >Take a bunch of scrap AC power transformers that are identical size, tear them apart and stack them 4-6 inches, and wind your own primary first (near the core, so insulation is symple), and zig-zag (accordian) wind secondary. Winding start is ground end,naturally. Insulation needed is layer-to-layer voltage plus some safety (2X maybe). AC power transformers are good to about 100KC depending on the drive. Above is for continuous use; can be much smaller if used in pulse mode. Experiment with an AC transformer soaked in transformer oil for a few daze, input pulses of (say) 1KV..
