How to design a high voltage Square wave oscillator?(1-5Mhz by 5kilovolt) - Page 1
Forum section: electronics / beginners

author: rozeh
author_rank: Regular Contributor
timestamp: December 03, 2013, 10:36:54 am
content: Hi guysHow can I design a high voltage Square wave oscillator?(1-5Mhz by 5kilovolt)

author: BravoV
author_rank: Super Contributor
timestamp: December 03, 2013, 10:57:15 am
content: ... Again, do you already know how to bias a transistor properly ?Start slow and not too overly ambitious, especially looking at many of your previous threads, almost all are way too advanced for your current knowledges and skills in electronics.To others that going to reply, please, save your breath, check his previous threads to get a clue.

author: rozeh
author_rank: Regular Contributor
timestamp: December 03, 2013, 11:00:38 am
content: Oh Bravo!I asked it just for I'm curios.

author: c4757p
author_rank: Super Contributor
timestamp: December 03, 2013, 11:29:32 am
content: A square wave must have harmonic frequency content. Let's say up to the 5th harmonic: 25 MHz for a 5 MHz wave.That is roughly a 0.35/5MHz = 14 ns rise time.14 ns from 0 to 5 kV is a 5kV/14ns = 357 GV/s slew rate.Now suppose you have 1 pF of parasitic capacitance. This will conduct I = C dv/dt = (1pF)(357GV/s) = 357 mA.That is about 1785 W instantaneous power, though the average power is a bit tricky to compute.In short, you don't even want tohavea 5 MHz 5 kV square wave, as it will be nearly impossible to contain. Forget actually generating one.

author: M. András
author_rank: Super Contributor
timestamp: December 03, 2013, 11:33:22 am
content: hmm sound like an emp generator

author: BravoV
author_rank: Super Contributor
timestamp: December 03, 2013, 11:37:42 am
content: Quote from: c4757p on December 03, 2013, 11:29:32 amHe wants to "design" one, not generating nor building it.

author: amyk
author_rank: Super Contributor
timestamp: December 03, 2013, 11:43:31 am
content: A sine wave would be much easier, although you'd still need equipment similar to a high-power AM radio transmitter...

author: lapm
author_rank: Frequent Contributor
timestamp: December 03, 2013, 12:34:15 pm
content: Quote from: BravoV on December 03, 2013, 11:37:42 amWhere have i hear that before? oh yes, just about any electronics forum where someone new to electronics decides to "design" high-voltage things. This usually happen before somewhat painful accident involving high-voltage and now little bit wiser electronic hobby builder. Not to mention that 5 kV potential to cause serious damage to other electronic devices.

author: eliocor
author_rank: Unknown
timestamp: December 03, 2013, 12:37:50 pm
content: please take care that the OP is asking for a 1-5milliHertz generator...

author: c4757p
author_rank: Super Contributor
timestamp: December 03, 2013, 12:39:05 pm
content: Quote from: eliocor on December 03, 2013, 12:37:50 pmDammit, I'm usually the Units Nazi who notices that one!

author: GK
author_rank: Super Contributor
timestamp: December 03, 2013, 12:56:55 pm
content: There wouldn't be anything particularly difficult in developing a 5kV sine wave <100kHz. Either a resonant oscillator or oscillator-driven amplifier driving a step up transformer would do the trick. Standard kind of thing in analogue oscilloscope CRT anode potential supplies. For a high(ish) fidelity square wave, one way to go about it would be to use a series (say 10) of fixed frequency phase-locked oscillators/step-up transformers, one operating at the fundamental frequency and the others at the harmonic frequencies out to the 10th, at the correct amplitudes. Then combine by connecting the transformer secondary windings in series.

author: poorchava
author_rank: Super Contributor
timestamp: December 03, 2013, 01:11:51 pm
content: Ok, I've done my deal of stupid and dangerous experiments (and probably gonna do a lot more...) but I wouldn't even consider building something like that.Don't you even try to do it before you learn the basics. This stuff would be absolutely lethal and quite likely to cause some serious material damage too.

author: peter.mitchell
author_rank: Super Contributor
timestamp: December 05, 2013, 03:01:04 pm
content: It's super easy, just do it mechanically, a spinning plate that connects two contacts, and a very very large step up gearbox, 120 million RPM, eeeeasssy

author: Neilm
author_rank: Super Contributor
timestamp: December 05, 2013, 06:55:49 pm
content: Assuming that the square wave was a decent square wave, there could be all sorts of issues with insulation. Generally the advice for insulation is not to change the voltage across it by more than 3-5kV/sec.

author: rozeh
author_rank: Regular Contributor
timestamp: December 07, 2013, 12:23:17 pm
content: Thanks guys

author: minime72706
author_rank: Frequent Contributor
timestamp: December 08, 2013, 03:54:14 pm
content: Quote from: rozeh on December 07, 2013, 12:23:17 pmWe're curious - what do you plan to do now?

author: rozeh
author_rank: Regular Contributor
timestamp: December 09, 2013, 07:43:31 am
content: Quote from: minime72706 on December 08, 2013, 03:54:14 pmWe can use of this oscillator for medical equipment(electron accelerator pump).

author: calexanian
author_rank: Super Contributor
timestamp: December 10, 2013, 03:38:35 am
content: I think we need to spend more time explaining why this is a terrible idea! Its a good way to piss all of your neighbors off for starters. They will be hearing it (Not to mention the harmonics, which being a square wave, its all harmonics) on the box springs of their mattresses! Any metal objects in the vicinity just just happen it hit a right wavelength will be dangerous. That much voltage and you do not even need an antenna at HF! The AM broadcast stations would love to visit with you too!

author: minime72706
author_rank: Frequent Contributor
timestamp: December 10, 2013, 03:41:45 am
content: Quote from: calexanian on December 10, 2013, 03:38:35 amI've always wanted to make a blast transmitter that uses a high voltage discharge to blast a wide range of radio frequencies. Wouldn't even have to try hard for AM.

author: calexanian
author_rank: Super Contributor
timestamp: December 10, 2013, 03:46:11 am
content: Quote from: minime72706 on December 10, 2013, 03:41:45 amThe first transmitters were spark gap type that just threw out wide band crap. Then somebody figured out a Filter for it. It was not much better.... Do a you tube search for a motorized spark gap transmitter.