The Spike

[MileHigh]

The real things to ignore are all of Jimboot's gratuitously malicious and ugly postings and his complete lack of common sense etiquette, Internet or not, and we can get on with this thread.  Sorry that he had to be such a fool as to post private correspondence without my permission.  He has gotten the message so hopefully he will listen.

Edit:

edit: The reason I posted the MH vile & abusive unprovoked message here, Is that he referenced this thread. I have never sworn or used expletives towards anyone here. I think that is a common courtesy we should extend to one another. Obviously as you can see MH does not agree. I still have no idea why he sent me his vitriolic paranoid ramblings. I think he wanted a gold star or something to show what a well behaved forum poster he is.

Why don't you stop being so full of crap and act like a real man instead of a lying little weasel?  You posted your message to show the world how to go about things in a completely wrong way and make yourself look like a complete idiot, it has nothing at all to do with me referencing this thread.  That's another ridiculous lie.  Wow, what an astute and impressive "Internet Marketing Consultant" you are.

[MileHigh]

1.5 V in, over 800 V out.  Circuit is a self triggering JT using principles illustrated by MH's sample circuit:

Way to go TK!  I think the fun part to my simple circuit is putting in the voltage divider so that you can measure really high spike voltages without damaging your scope.  If Patrick or his peers build the circuit, they can take some big coils and up the resistance values and see how high they can push it without fear.

For Patrick:  If you were going to start going for higher and higher spike voltages, you will see that the coil discharges in a shorter and shorter amount of time.  So that means that all of the spike energy stored in the coil will be burnt off in the high-value resistance in one shot.  That presents its own problems and I will discuss that.

Suppose that your coil stores five joules of energy with one amp flowing through it and you put a 1/2 watt 10K resistor for R1 and a 1/2 watt 200-ohm resistor for R2.  You are trying to make a 10 kilovolt spike.  Chances are all of that energy being instantly dissipated in the 10K resistor in a fraction of a second will make it explode.   So what you will have to do is simply make a string of 10 1k-ohm 1/2 watt resistors in series.  Then all of the energy in the coil will be instantly dissipated but distributed over all 10 resistors and you will be fine.

MileHigh

[MileHigh]

I went too far when I discussed very very high spike voltages.  I also forgot to discuss the practical limits to the maximum spike voltage as it pertains to the transistor and the signal generator.  Depending on the transistor you use, there are specifications for the maximum collector-emitter and collector-base voltages it can sustain when it is switched off.  For the signal generator output, something like a "totem pole" of a series of very fast switching diodes across the output that will conduct starting at perhaps five volts above the nominal high signal generator output would be a suggestion.  This would be to protect the signal generator output if the transistor were to break down from high voltage.  That's where people like TK could give you some solid advice.

Instead of seeing how high you can push your spike voltage, keeping it a reasonable and safe distance away from the break-down voltages of the transistor or MOSFET would be the wise way to go.  After all, the purpose of the investigation is not to see how high you can push the spike voltage, it's to understand how to control and use the spike.

Say for the sake of argument that your transistor can withstand 750 volts when it is switched off.  If you keep the spike voltage to 500 volts and less, you should be fine.  You should not need a totem pole of protection diodes on the signal generator output either.  The real point of the test circuit is to see how a coil generates a spike, and the time it takes for the decay of the spike, for different initial currents through the coil, and for different values of load resistor.  You don't need to see the spike voltages to go into the stratosphere for that.  When you look at the case for an ideal inductor of any inductance value, the theoretical maximum spike voltage is infinity.

If you understand how the spike works and try different coils, try different timings and associated initial currents, and different load resistors, then when you start doing other experiments with pulse motors and related stuff you will understand what you are observing and be in a position to modify and adapt your circuits to your applications.

"Radiant energy" has nothing at all to do with this investigation.  An equivalent mechanical test bed would be a series of flywheels that you spin up to different speeds.  Then you apply disk brakes to the spinning flywheel and measure the force that the spinning flywheel imparts on the disk brakes.  The faster and with more force the disk brakes clamp down on the spinning flywheel the more force will be imparted on the disk brake assembly.  That force is the mechanical equivalent to the voltage spike.

MileHigh

[EMJunkie]

I went too far when I discussed very very high spike voltages.  I also forgot to discuss the practical limits to the maximum spike voltage as it pertains to the transistor and the signal generator.  Depending on the transistor you use, there are specifications for the maximum collector-emitter and collector-base voltages it can sustain when it is switched off.  For the signal generator output, something like a "totem pole" of a series of very fast switching diodes across the output that will conduct starting at perhaps five volts above the nominal high signal generator output would be a suggestion.  This would be to protect the signal generator output if the transistor were to break down from high voltage.  That's where people like TK could give you some solid advice.

Instead of seeing how high you can push your spike voltage, keeping it a reasonable and safe distance away from the break-down voltages of the transistor or MOSFET would be the wise way to go.  After all, the purpose of the investigation is not to see how high you can push the spike voltage, it's to understand how to control and use the spike.

Say for the sake of argument that your transistor can withstand 750 volts when it is switched off.  If you keep the spike voltage to 500 volts and less, you should be fine.  You should not need a totem pole of protection diodes on the signal generator output either.  The real point of the test circuit is to see how a coil generates a spike, and the time it takes for the decay of the spike, for different initial currents through the coil, and for different values of load resistor.  You don't need to see the spike voltages to go into the stratosphere for that.  When you look at the case for an ideal inductor of any inductance value, the theoretical maximum spike voltage is infinity.

If you understand how the spike works and try different coils, try different timings and associated initial currents, and different load resistors, then when you start doing other experiments with pulse motors and related stuff you will understand what you are observing and be in a position to modify and adapt your circuits to your applications.

"Radiant energy" has nothing at all to do with this investigation.  An equivalent mechanical test bed would be a series of flywheels that you spin up to different speeds.  Then you apply disk brakes to the spinning flywheel and measure the force that the spinning flywheel imparts on the disk brakes.  The faster and with more force the disk brakes clamp down on the spinning flywheel the more force will be imparted on the disk brake assembly.  That force is the mechanical equivalent to the voltage spike.

MileHigh

MileHigh is right here!

The Inductive Spike is E = -LdI/dt - All this means is that the Magnetic Field, Stored in the Inductor, which is the LdI part, the Negative sign, which is the Polarity reversal, and dt is the Time Rate of Change.

Its simply Induction, it all comes from the Induction Law emf = -NdPhi/dt - Its the same thing!

Radiant Energy/Cold Current, really is a bunch of Horse Malarkey Rubbish! Designed to have people running down Rabbit Holes chasing Magic Rabbits! Its all Induction, it will never ever change.

   Chris Sykes
       hyiq.org

P.S: Yes I used to get sucked into this Radiant Rubbish before I knew better.

[MileHigh]

The Inductive Spike is E = -LdI/dt - All this means is that the Magnetic Field, Stored in the Inductor, which is the LdI part, the Negative sign, which is the Polarity reversal, and dt is the Time Rate of Change.

You are close but let me fine tune it.

The voltage generated by a coil of inductance L:  E = LdI/dt

But how do you relate that to what I state in my previous posting?  If the load resistor is zero, then the current through the coil will not change, so then:  E = 0 = LdI/dt where  dI/dt is zero.

The higher the value of the load resistor, the higher the initial voltage and the faster the coil will discharge its stored energy and the faster the current will change:  dI/dt will be a high value for a high value of load resistor.

We can look at the initial conditions to get a handle on what the equation means the instant the coil starts discharging through the load resistor:

We know that the initial voltage is simply the current through the coil times the value of the load resistor: V-initial = (I-initial *R)

So at the instant the coil starts discharging we can say this:  (I-initial *R) = (L * dI/dt)

Therefore the rate of change of the current waveform at the instant discharging starts is: dI/dt = (I-initial *R)/L = V-initial/L

Therefore: L = V-initial/(dI/dt)

That means that by looking at the slope of the current waveform when the coil starts discharging and measuring the initial voltage you can determine the inductance of the coil.