Winfield Hill wrote:> 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-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? Jeroen Belleman
25kV AC
Started by ●September 30, 2019
Reply by ●September 30, 20192019-09-30
Reply by ●September 30, 20192019-09-30
Two CRT flybacks + pair 6BK4C + HV optos to drive them (since Vgk ~ 100V). :^) One flyback needs to be heavily isolated, suggest LEDs + PV for expedient isolation; otherwise, a custom resonant transformer will do. Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/ "Winfield Hill" <winfieldhill@yahoo.com> wrote in message news:qmsfbm02m7s@drn.newsguy.com...> 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, > - Win
Reply by ●September 30, 20192019-09-30
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. -- Bill Sloman, Sydney
Reply by ●September 30, 20192019-09-30
Tim Williams wrote...> > Two CRT flybacks + pair 6BK4C + HV optos to drive them > (since Vgk ~ 100V). :^)Flyback plus HV diode, one each for pos and neg pulsing, into a 35kV cap, make a 25kV square wave? But we also do need some time at zero volts. -- Thanks, - Win
Reply by ●September 30, 20192019-09-30
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. -- Thanks, - Win
Reply by ●September 30, 20192019-09-30
On 2019/09/30 7:05 a.m., Winfield Hill wrote:> Tim Williams wrote... >> >> Two CRT flybacks + pair 6BK4C + HV optos to drive them >> (since Vgk ~ 100V). :^) > > Flyback plus HV diode, one each for pos and neg > pulsing, into a 35kV cap, make a 25kV square wave? > But we also do need some time at zero volts. > >B&W TVs used ~15KV flybacks running around 15,756KC and were AC output until the HV diode which was external in many cases. Is the frequency a problem? If not then as suggested use a colour TV flyback and cut open the shell to remove the HV diodes and that will probably work. Flybacks are in the uA range, and I assume you aren't looking for any current here. A single flyback would then suffice. Still available from sources such as: https://www.goldmine-elec-products.com/ Possibly http://www.surplussales.com I have a small pile of colour TV flybacks from both projectors and TVs - any one of which will likely work. 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.When I was a kid, we'd bum old neon sign transformers from the sign companies. I had a nice 18KV unit with an insulator on each end. I guess neons are all high frequency now, or fake-neon LED things. Maybe there are some old trannies around. I think neon looks better with 60 Hz drive. The high-freq stuff looks fuzzy or something. I recently tested a Hammond toroidal 50/60 Hz power transformer. It worked fine to over 50 KHz. Most power transformers work fine in the audio range. You might make some HV DC, and drive an h-bridge to make a sine. It wouldn't be unreasonable at your power levels. Or some C-W multipliers where you modulate the input. Discharge could be slow at your frequency. There are maybe possibilities for push-pull C-W. How about car ignition coils and rectifiers, or commercial HVDC modules, back-to-back? Needs a little management. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●September 30, 20192019-09-30
On 30.9.19 11:45, 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 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. -- -TV
Reply by ●September 30, 20192019-09-30
On Mon, 30 Sep 2019 07:53:18 -0500, "Tim Williams" <tiwill@seventransistorlabs.com> wrote:>Two CRT flybacks + pair 6BK4C + HV optos to drive them (since Vgk ~ 100V). >:^) > >One flyback needs to be heavily isolated, suggest LEDs + PV for expedient >isolation; otherwise, a custom resonant transformer will do. > >TimTubes are not a bad idea at all here. A fiberoptic fed cascode would be fun. 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. Watch out for x-rays. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●September 30, 20192019-09-30
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. -- Thanks, - Win
