Argh, yeah I see the problem 🙁
There must be some way of doing it...
I've heard of people seriesing two of them with no problem, so maybe if I do four and put the centre one to ground it will work?
There must be some way of doing it...
I've heard of people seriesing two of them with no problem, so maybe if I do four and put the centre one to ground it will work?
Or just look around for an appropriate transformer. There are tons on eBay. And even if the ratings don't suit you, if you are much into DIY, it's not hard once you have an appropriate core to take the transformer apart and rewind it.
Simplicity vs convenience
Slartibartfast (recent thread activity) 🙂
Drawn between two methods of driving the main coil; FET or triode based.
FETs appear to be more simple to work with than triodes, also much more
efficient. However at frequencies beyond 1MHz, with stray EMF, RF etc.
I am not longer sure that the environment is the best for a crude FET design.
Triodes would be more forgiving...
Slartibartfast (recent thread activity) 🙂
Drawn between two methods of driving the main coil; FET or triode based.
FETs appear to be more simple to work with than triodes, also much more
efficient. However at frequencies beyond 1MHz, with stray EMF, RF etc.
I am not longer sure that the environment is the best for a crude FET design.
Triodes would be more forgiving...
Attachments
Re: Simplicity vs convenience
Well mosfets typically fail closed, so your 300V would be directly shorted to ground in this case. If you can sense that surge and shut things down in time....
Alternatively, the mosfet is going to blow apart.
Also, mosfets tend to fail with all pins closed, so the gate will apply the 300V to your 12V follower, and take that out as well.
It's perhaps less likely for the bjt's to fail in the same way, so if you include another buffer in driver path, the later may protect the first when it blows.
You could employ galvanic isolation via a few different means, or try a number of other things..
Fets may be cheaper to work out the bugs with than tubes.. I'd think they'd have to be easily available at least.
Is that any help at all?
Indalhc said:
Well mosfets typically fail closed, so your 300V would be directly shorted to ground in this case. If you can sense that surge and shut things down in time....
Alternatively, the mosfet is going to blow apart.
Also, mosfets tend to fail with all pins closed, so the gate will apply the 300V to your 12V follower, and take that out as well.
It's perhaps less likely for the bjt's to fail in the same way, so if you include another buffer in driver path, the later may protect the first when it blows.
You could employ galvanic isolation via a few different means, or try a number of other things..
Fets may be cheaper to work out the bugs with than tubes.. I'd think they'd have to be easily available at least.
Is that any help at all?
Lifter vehicle + modified plasma tweeter driver
Certainly d: I was looking into optocouplers earlier but couldn't find one fast enough.
And since the signal is a square wave, transformers would have a problem also...
classd4sure said:
Certainly d: I was looking into optocouplers earlier but couldn't find one fast enough.
And since the signal is a square wave, transformers would have a problem also...
Triodes vs FETs (and BJTs) continued...
About the recently linked to 2A3/45 based amplifier schematic,
Both the 2A3 and the 45 are built for audio frequencies, and since the input
is a PWM signal at radio frequencies a triode like the 811A is a better choice.
To start somewhere in this, the PWM section is probably the best place, to make
this work properly before deciding further on what the power amp section might
eventually look like. And then to do the testing on some (very) low voltage coil.
About the recently linked to 2A3/45 based amplifier schematic,
Both the 2A3 and the 45 are built for audio frequencies, and since the input
is a PWM signal at radio frequencies a triode like the 811A is a better choice.
To start somewhere in this, the PWM section is probably the best place, to make
this work properly before deciding further on what the power amp section might
eventually look like. And then to do the testing on some (very) low voltage coil.
Galvanic isolation
I guess a toslink would work, if I could find a good hack for it. Maybe a little
complicated, also this isn't really a problem if the design is made right in
the first place.
edit:
Eh, maybe not 🙄
A nano-meter modulated optical link would have Gigahertz resolution (at the
least), that should work
I guess a toslink would work, if I could find a good hack for it. Maybe a little
complicated, also this isn't really a problem if the design is made right in
the first place.
edit:
Eh, maybe not 🙄
A nano-meter modulated optical link would have Gigahertz resolution (at the
least), that should work
Re: Galvanic isolation
What exactly do you intend on driving? What are the requirements of it? Voltage, frequency, bandwidth, current/ impedance across that bandwidth?
Regards,
Chris
Indalhc said:
I guess a toslink would work, if I could find a good hack for it. Maybe a little
complicated, also this isn't really a problem if the design is made right in
the first place.
edit:
Eh, maybe not 🙄
A nano-meter modulated optical link would have Gigahertz resolution (at the
least), that should work
What exactly do you intend on driving? What are the requirements of it? Voltage, frequency, bandwidth, current/ impedance across that bandwidth?
Regards,
Chris
Lifter vehicle + modified plasma tweeter driver
Driving a base fed 'quarter wavelength' tesla coil. The voltage requirements are 6 (for testing) to some 1500 Volts (contemporary solid–state plasma tweeter designs using from 60 to 170 Volts successfully), frequency >1 <10 MHz, current giving 40 Watts/square foot eventually, impedance, not so good at the math here d:
I looked for IGBTs and couldn't find any at this frequency range, aren't these the same as BJTs?
classd4sure said:
Driving a base fed 'quarter wavelength' tesla coil. The voltage requirements are 6 (for testing) to some 1500 Volts (contemporary solid–state plasma tweeter designs using from 60 to 170 Volts successfully), frequency >1 <10 MHz, current giving 40 Watts/square foot eventually, impedance, not so good at the math here d:
I looked for IGBTs and couldn't find any at this frequency range, aren't these the same as BJTs?
Lifter vehicle + modified plasma tweeter driver
In at least one of the 'contemporary solid state plasma tweeter designs' the
feed to the coil is by induction, ie not a base feed.
Sorry about suggesting a BUZ 100 some weeks ago. It shouldn't be difficult
though to find a more suitable FET for megahertz operation.
This project is still on, even though the thread has been rather silent lately
In at least one of the 'contemporary solid state plasma tweeter designs' the
feed to the coil is by induction, ie not a base feed.
Sorry about suggesting a BUZ 100 some weeks ago. It shouldn't be difficult
though to find a more suitable FET for megahertz operation.
This project is still on, even though the thread has been rather silent lately
Re: Lifter vehicle + modified plasma tweeter driver
Hopefully the resulting invention wont be 😀
Indalhc said:The thread has been rather silent lately
Hopefully the resulting invention wont be 😀
Lifter vehicle + modified plasma tweeter driver
I hope to present an application that has a bass response,
within this summer 🙂
I hope to present an application that has a bass response,
within this summer 🙂
Success 😀
I now have very fainth sound with a 6 kV or so supply and a 100 volt line transformer.
I now have very fainth sound with a 6 kV or so supply and a 100 volt line transformer.
I think the very low spl is because of the HV supply, I measured 0,5 volt over a 1 megaohm resistor, that's 0,5 µA.
The HV supply is made of a cascade with 25 33nF capacitors, 25 1N4007 diodes and 230 volts ac.
Once I tested it with 6 volts ac and when I measured it the voltage collapsed to 24 volts while my multimeter has an input resistance of 10 megaohms!
So it's not very good, supplying miliwatts at best.
The HV supply is made of a cascade with 25 33nF capacitors, 25 1N4007 diodes and 230 volts ac.
Once I tested it with 6 volts ac and when I measured it the voltage collapsed to 24 volts while my multimeter has an input resistance of 10 megaohms!
So it's not very good, supplying miliwatts at best.
😱 😱 You've gotten something to work?? 😀 Even though the sound is faint, is it any good? As you said, the faintness could be due to the low current supplied. However, you can get ion generators that can supply up to about 400 microamps 
so this might be worth looking into! The supply I made had 30 220nF caps and 30 1N4007s. It's currently broken at the moment (easily fixable, a couple of loose solder joints) but once I fix it I'll get hold of 1 or 2 100v line transformers and experiment! Got a photo of your setup?
so this might be worth looking into! The supply I made had 30 220nF caps and 30 1N4007s. It's currently broken at the moment (easily fixable, a couple of loose solder joints) but once I fix it I'll get hold of 1 or 2 100v line transformers and experiment! Got a photo of your setup?I couldn't really judge the sound with this low spl, but it wasn't horribly distorted.
100 volt line transformers are not that good, it's better to get some toroids or even better esl stepup transformers.
I just calculated that the HV supply can deliver a whopping 3 miliwatts, even when it's shorted with a 1 megaohm resistor it can't deliver more than 230 microampere.
I might build one of those lifter power supply's, I would say I need at least 10 kV and 1 mA.
I made the needle negative and the tube positive, if you want to check if it does anything at all, you should feel a small breeze coming from it with an ozone smell.
Pics will come tomorrow.
100 volt line transformers are not that good, it's better to get some toroids or even better esl stepup transformers.
I just calculated that the HV supply can deliver a whopping 3 miliwatts, even when it's shorted with a 1 megaohm resistor it can't deliver more than 230 microampere.
I might build one of those lifter power supply's, I would say I need at least 10 kV and 1 mA.
I made the needle negative and the tube positive, if you want to check if it does anything at all, you should feel a small breeze coming from it with an ozone smell.
Pics will come tomorrow.
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