Donald Smith Devices too good to be true

[janost]

Never mind.
I now have something that oscillates on DC and it is better than any bipolar transistor.

When it shorts to ground it does so with 0.33ohms and when it is open it's like 500Kohm open.

Who needs bipolar transistors anyway

[Gedfire]

Pulsed DC to Capacitor

Most likely overvolt.

C1/D1 is a voltage doubler circuit so the output from it is a peak 333v.

And the 400v capacitor cannot handle it with high current when it is initially empty and charged.

Thank you Janost,

It's an honour to hear from you.

Just to be sure, you mean that I should get a capacitor of over 500 volts or more then? Is it high current or voltage or both that does the damage?

If I place 12 volts at 100 amps onto the plates of a 20 volt capacitor would it explode?


Best regards,

Gary Dunn

[Gedfire]

Pulsed DC to Capacitor

Hi Ged. Your full wave diode bridge rectifier is not shown connected up properly in your attached circuit diagram. If you connected it up as is drawn in the circuit diagram, you would be getting a near dead short across your AC source on negative swings, depending on what the actual capacitance value is for C1. If C1 is a small value, it should be OK though. Is that how you actually had everything connected? Anyway, if you did not connect your fullwave bridge rectifier up correctly to an electrolytic capacitor such that it wasn't always getting positive DC to its positive lead and negative DC to its negative lead, this can make electrolytic caps explode. You need to be careful with that as an exploding cap can be dangerous. Also, what type of capacitor were you using for C1, and what is its voltage rating? Was it C1 or C2 that exploded?
This is how a full wave bridge rectifier should be connected in:

Hi Level,

Thanks for answering. C1 was taken form a television set.Its voltage rating was 1500v and capacitance approximately 220 nF

C2 (the one across the diode bridge) was the one that exploded.

Regards,

Ged

[Gedfire]

Full Wave

Yes, it wouldn't be a short if you are using a small value for the capacitance, as I mentioned. If a very large value of capacitance is used it would act more like a short, but then you would pop a breaker or blow a fuse if the current draw was too high. Gedfire didn't mention what value he is using for his C1. Also, Gedfire mentioned a 'diode bridge', so I was assuming he was intending a full wave bridge rectifier setup. The way he has it connected in now would not be a proper full wave bridge setup, but maybe that is how he intended it. I wouldn't think that 340V peak would cause a 400V electrolytic to get damaged, but I haven't played around with circuits like that, so not certain. Maybe there is something else going on there. Accidentally hooking up an electrolytic capacitor backwards could definitely cause it to explode though, especially at those kind of voltages.

Yes level, just had another look at the schematic.I did not do it properly.It was supposed to be a full wave rectifier.

I would like to know if I pulsed DC to a capacitor through a diode bridge at 50hz or 30khz, @ 110 volts to a 500 volt 2 uF Capacitor, all other things been correct, would it explode from over voltage.If yes how can that be prevented without switching off the power.

Regards,

Gary

[mr.clean]

Why does the true-RMS DMM say that the current drawn is 390mA and I measure it with a scope over a dropresistor to 160mA?

Is it because it cant handle the waveform?

what you do is take the reading that you like better

just jokin, i'd trust the resistor volts across 1 ohm = amps, as you know.

then regardless of exotic waves, you see what actually made it thru

[janost]

Thank you Janost,

It's an honour to hear from you.

Just to be sure, you mean that I should get a capacitor of over 500 volts or more then? Is it high current or voltage or both that does the damage?

If I place 12 volts at 100 amps onto the plates of a 20 volt capacitor would it explode?


Best regards,

Gary Dunn

Keep the volts below halv the rating of the capacitor and it should hold

[janost]

what you do is take the reading that you like better

Just jokin, i'd trust the resistor volts across 1 ohm = amps, as you know.

then regardless of exotic waves, you see what actually made it thru

Yes, I measured across a resistor because I did not belive what the DMM said.

Right now I dont care. It works and I will make something of it.

[janost]

Thank you Janost,
If I place 12 volts at 100 amps onto the plates of a 20 volt capacitor would it explode?

It has to do with the ripple rating of the capacitors.
To much ripple will blow them up.

[citfta]

What?!

Where do you people get this stuff? I have worked in electronics for over 50 years and have never heard of a "ripple rating". The only way to damage a capacitor is by over-voltage. If you rapidly charge and discharge one you can get them to overheat. But in normal use only over-voltage will actually harm them. They are used to reduce the ripple from the rectifier. They were used in the days of tube type rectifiers and are still used for the same purpose today with solid state rectifiers or diodes. There are many other uses but none where you would have to worry about the ripple rating if such a thing really existed.

To give a real answer to Gedfire's question about 12 volts and 100 amps to a 20 volt rated cap, the answer is the cap will charge to 12 volts at whatever capacity it is. It makes no difference what amperage you have available the cap will only hold what it is designed to hold as long as you don't exceed the rated voltage by too much. Also you should know the voltage marked on the cap is the normal working voltage. Sometimes there will also be the maximum voltage marked on the cap as well. It is perfectly safe to operate the cap at it's rated voltage as long as you know there aren't any spikes that might exceed that voltage by a large amount. A cap will absorb some pretty large spikes without any damage and in some cases that is exactly what they are used for.

Respectfully,
Carroll

[mr.clean]

Yes level, just had another look at the schematic.I did not do it properly.It was supposed to be a full wave rectifier.

I would like to know if I pulsed DC to a capacitor through a diode bridge at 50hz or 30khz, @ 110 volts to a 500 volt 2 uF Capacitor, all other things been correct, would it explode from over voltage.If yes how can that be prevented without switching off the power.

Regards,

Gary

hi man, i have had some luck charging electrolytics, but i have also blown them up with as little as my Bedini motor
if its a dry cap (oil filled and no polarity) then it can handle abuse a little better, but they basically need to be rated for the voltage you are hitting them with.

...the reason is to me not so much dangerous they just arc over internally, and you see nothing happening but the sound of an overworked spark gap in short circuit
(from my experience they get dangerous when they are FULL and still recieving charge and no load using it)
...and like overvolting bulbs, there is no light because the pos and neg have found an easier way to reach eachother, and avoid the load, (or charging the cap) even tho the power is possibly there.

that being said, the familiar Big 4 caps on my double helix Smith board are only rated 2kv and in parallel they are only 40 uf....

....but my point is they charge Excellent even tho im applying more than 30,000 v! (but the diodes are always too hot, anyway)

one thing about that is tho, the caps seem to need to be entered from the outer ends like Don's,
if you hook up all caps in para, then connect to the terminals on only one cap, and it will favour that cap and arc internally.
but if you enter the caps from the opposite ends, it seems to work great

my only particular problem is the caps on my double helix board wont charge if on load. only if they are intermitantly on and off to be able to build up (wierd i know)
Thats why ive recently taken off the coils and am experimenting that way, and am seeing the best results yet. (but not using large storage caps)
Now im basically matching the supply of power from NST and Earth, at 60 volts .4 amps input, it fills 10kv @.1uf =5 Joules at spark freq about 250hz resulting approx 50 watts output (as seen in my last vid)

IT IS WAY MORE than the NST only, as seen in my last vid, and a person is almost guaranteed to be dead if you got in between the hot and ground wires lol
...ONE pop from 10kv.1uf and you will Never forget it (ive done it lots).... but 10kv.1uf ...250 times in one sec?!?... hmm i dont think i could handle that
anyway, dont blow up

[mr.clean]

caution... this could be you

High voltage capacitor bank vs watermelon - YouTube

[level]

...
I have worked in electronics for over 50 years and have never heard of a "ripple rating". The only way to damage a capacitor is by over-voltage. ...

It is actually called the Ripple Current rating.

Capacitor Ripple Current Rating

Ripple Current
Ripple current is the AC component of an applied source (often a switched-mode power supply) (whose frequency may be constant or varying). Ripple current causes heat to be generated within the capacitor due to the dielectric losses caused by the changing field strength together with the current flow across the slightly resistive supply lines or the electrolyte in the capacitor. The equivalent series resistance (ESR) is the amount of internal series resistance one would add to a perfect capacitor to model this. Some types of capacitors, primarily tantalum and aluminum electrolytic capacitors, as well as some film capacitors have a specified rating value for maximum ripple current.

Tantalum electrolytic capacitors with solid manganese dioxide electrolyte are limited by ripple current and generally have the highest ESR ratings in the capacitor family. Exceeding their ripple limits can lead to shorts and burning parts.

Aluminium electrolytic capacitors, the most common type of electrolytic, suffer a shortening of life expectancy at higher ripple currents. If ripple current exceeds the rated value of the capacitor, it tends to result in explosive failure.

Ceramic capacitors generally have no ripple current limitation and have some of the lowest ESR ratings.

Film capacitors have very low ESR ratings but exceeding rated ripple current may cause degradation failures.

[citfta]

My apologies!

Well I learned something new. I have never seen that before. I apologize for my comments. How do you know what the ripple rating is? I have never seen that on a cap. I guess you have to go back to the manufacturer for the ripple limits and look at the data sheet. At least I am not so old I can't learn something new.

Thanks for the info,
Carroll

[level]

Well I learned something new. I have never seen that before. I apologize for my comments. How do you know what the ripple rating is? I have never seen that on a cap. I guess you have to go back to the manufacturer for the ripple limits and look at the data sheet. At least I am not so old I can't learn something new.
Thanks for the info,
Carroll

No Worries. I had learned about it years ago, but had forgotten about it myself until janost pointed it out as a possible cause of Ged's electrolytic capacitor failure. I think this spec is not very commonly made use of, unless maybe for people who design power supplies and regulators and inverters and that sort of thing. Some of the larger electronic supply outlets like Digikey have info on it. For example, if you scroll to the right in this capacitor search criteria selection grid at Digikey, they have a column for filtering your search based on Ripple Current.
DigiKey - Aluminum Capacitors

[soundiceuk]

Hi everyone!

The lid is off the Don Smith files!!!!

I am going to be removing the files from my Dropbox very soon because I need the hard drive space.

After a disaster with my hard drive I haven't got some of the videos, Editior and Mladen helped me with.

I also haven't got a copy of Don Smith's Library anymore.

For those of you who have the files, feel free to share as much as you want.

All the best!

Paul