Does anyone have any experience of working with Vacuum tubes and related technologies of the turn of the 19th century?

A lot of what I read about past inventions seems to refer to the use of vacuum tubes - such as Tesla's electric car, or his experiments with high voltage spikes.  Other free energy devices of the past seem to have utilised them as well.

I think that as we have moved away from early equipment which was very analogue and "real world" we have abstracted away towards digital components and chips etc that provide an approximation or facsimile of the effects of their analogue counterparts.  The digital components have been created to do a specific job very well and electronics have benefitted greatly as a result - they are consistent and have very restricted tolerances etc.

I think there could be some interesting advances to be made in trying to stay as close as possible to the analogue equipment of the past and faithfully trying to replicate the physical features of the systems in question rather than arrive at the same end state through the use of modern equivalents.

So back to my original question - have we lost the skill set to use the likes of vacuum tubes in our electrical experiments these days?  Is anyone aware of anyone working with old tech / any youtube replicators etc?

Cheers,

Sy

Only area that still warrants using vacuum tubes is Rife machines, and even then I've built them using solid state devices (ferrite rods). I started out with valves in the 1960s but can't see a use for them in almost 100% of applications these days.

There is one aspect that was lost switching to solid state devices. There are two aspects that tubes have that solid state devices do not.

One aspect is that some of the tubes had radioactive substances on the cathode. So when it was heated it would generate a lot electrons from the cathode that would be attracted to the positive anode. Keep in mind that tubes were developed before the nuclear bombs and government control of radioactive substances didn't occur until after it was proven that they could be used in weapons. Before that there were no controls whatsoever on radioactive materials. I believe Henry Moray's "valves" used radio active materials and that may have been why the government men started harrassing him. If I remember correctly some of Tesla's work also used radioactive materials. With these tubes one could litterally add power to the circuit in an amplifier whereas today's amplifiers can only control the circuit from it's peak to lower powered state. Today, handling radioactive materials has nearly been turned into a phobia but there are some which can be safely handled and in fact some can be bought over the internet. Pitchblende which is the source of uranium, for example, can be safely held in the hand. It is the highly refined pitchblende that is dangerous. Thorium can also be purchased over the internet. The safety guidelines for radioactive materials were developed from the results observed from the nuclear bomb detonations in Japan and linearized backwards. But there is a threshold below which radiation is enourmously more safe. This threshold which was known at the time was intentionally ignored when developing the guidelines.
Toxicologist says NAS panel 'misled the world' when adopting radiation exposure guidelines

The other aspect that is lost with solid state devices is the ability to do absolutely unidirectional circuits. There is always some reverse leakage in the solid state devices whereas that is not possible with tubes.

Threre might be one other aspect but I'm not sure about this one because I don't know enough about tube operation but I think you can get faster pulse fall times with tubes. Anyone familiar with tube operation want to address that?

The spark gap also has some attributes that can't be reproduced in solid state devices. It was the diode of Tesla's time.

Quote from thx1138v2 on April 5th, 2014, 05:16 AM

The spark gap also has some attributes that can't be reproduced in solid state devices. It was the diode of Tesla's time.

Diode or high voltage switch?

I have found a spark gap to be a most amazing high voltage switch, but as a diode...?  Never crossed that in my experiments.

http://www.sparkbangbuzz.com/els/iposc-el.htm


check this out. How to make a home made semi conductor.. :D :D :D

http://www.sparkbangbuzz.com/els/zincosc-el.htm

Quote from Matt Watts on April 5th, 2014, 03:51 PM

Diode or high voltage switch?

I have found a spark gap to be a most amazing high voltage switch, but as a diode...?  Never crossed that in my experiments.

That's what the quenched spark gap is about. Start the arc from one electrode to the other and quench it before any backflow occurs. That's what Tesla was doing to create his high voltage, high frequecny, unidirectional impulses. The unidirectional part of that is important and it's one of the reasons he spent so much time developing what he called "interrupters".

Thing is, if you take a spark gap, quenched or not and reverse the current, it will happily flow the other way just as easily.  I spark gap has no polarity associated with it like a diode does.

The main reason for interrupters is to decrease the time of the arc and in-turn increase the intensity of the impulse.  Normally a spark gap, once arced will continue until the energy supply depletes down to some level.  So one charged capacitor will only give you one arc--it may last a while, but only one arc.  The interrupter will allow you to have multiple arcs from a single charge of a capacitor.  This is where I and probably Tesla as well, discovered it's not a zero sum game here.  With the same energy contained in a capacitor, discharging it in multiple pulses versus a single pulse, differs.  The multiple pulses will do more work in the system, so the shorter those pulses are and the more of them you can get from a single charge, the better the results.  Some refer to this as higher frequency, which is partially correct, though it is not a sine wave we are talking about here, it is impulses and the two are completely different.

If you look at a scope trace of a full-wave bridge rectified sine wave, those humps may look like impulses, but they are not.  Not even a trained eye could tell the difference.  In order to know which is which, you have to know how the signals were created.  And I can tell you from experience two signals generated that look identical on an oscilloscope, one from a fully electronic function generator and another from a capacitive discharge, high speed quenched spark gap are simply not the same, at all.  The spark gap signal will contain all sorts of extreme high frequency harmonics, even though you cannot see them on the scope.  This won't be obvious until you begin to pass the two signals though various other components, then you'll see the difference.  The impulses will negotiate obstacles/impedances the other signal simply cannot get through.

I agree with all of that. I guess I should have called it the semiconductor of Tesla's day rather than a diode, a semiconductor being something that conducts under one set of circumstances and insulates under a different set of circumstances which describes the gas in the spark gap. Doping in Tesla's day was achieved using different gases and gas densities and pressures in the gap between the electrodes.

A pulse is a complex package of sine waves. You can deconstruct it with a Fourier transform directly into its component waves, or build any waveform shape from sine waves. A spark gap is fairly random in the shape it produces, really low tech.

A quick study of Software Defined Radio will show how far we've come in this area.

Quote from haiqu on April 8th, 2014, 08:05 PM

A quick study of Software Defined Radio will show how far we've come in this area.

Holy cow!  I had no idea.  Last I remember was the packet radio stuff sometime around 1995.  Now we have ADCs and DACs that can run fast enough to actually encode the RF waveforms on the fly.  Fantastic.

Started playing with it in 2003 when the SDR-1000 radio was released by US ham Gerald Youngblood. Truly awesome capabilities.