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Author Topic: Dally, Shark & Ruslan workbench  (Read 72388 times)
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I think it is this one below.  Normally there is an antenna wire connected to the base of the Q6 and its collector drives the Kacher coil, but for the purpose of this test I asked Itsu to put a temporary resistor in its place and disconnect the antenna wire from the base.

OK, if the 4093 is connected to the 2113 as in the Stalker schematic is post #371 and the 2113 outputs are connected as shown in your schematic, Lin is low and Hin is high prior to the rising edge of the pulse into pins 1,2 of the 4093.  The inverted logic change on Hin will be delayed by ~100ns from any change on Lin.  In the state described above, Q5 will be on and Q4 will be off forcing the BJT Q6 to be turned on however, this is not the quiescent state shown in the scope traces. 

If the base triggering is based on the falling edge of the pulse to pins 1,2 of the 4093, the logic levels are the complement of the above and there would be a possibility of the "miller" effect coming into play with the early turn off of Q4 as the gate voltage is rapidly brought to ground with the gate to drain capacitance pulling the base voltage of Q6 below ground as seen.  After the mentioned delay above plus delays in Q3, Q5, and the 2113, Q5 turns on and  then supplies a positive current to the base of Q6 as seen in the rising base voltage.

I must say that it is late here so I may be missing something or anything!!

Regards,
Pm
   

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I am looking for a schematic of how any coils and "antenna" are connected to the PCB screw terminals.

Hi PW,

here a drawing.

Regards,
Vasik


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Thanks, but I have that schematic.  It, and the board layout, were posted a couple pages back. 

I am looking for a schematic of how any coils and "antenna" are connected to the PCB screw terminals.  From Itsu's videos, it appears there is also a battery connected somewhere around J2 as well as what appears to be three coils on a form connected to the same connector.  But I'm just guessing.

Without seeing a schematic of how and what is connected to the screw terminals, it is hard to follow along.   

Also, it looks like an additional terminal set has been added just below C17 on the bipolar side.   

PW 

 


PW,  see also Vasik his reply drawings.

see this diagram where J2 is connected to:




J4 is 24V input
J3 and J8 are push Pull (from delayed TL494) connectors going to the Yoke coils, see this diagram:



The additional terminal is added by me to get and extra inverted output of the 4093 to drive an optional MOSFET (instead of transistor) to drive the kacher.
see this diagram:
 


Itsu
   
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Hi PW,

here a drawing.

Regards,
Vasik

Vasik,

Thanks, that is what I was looking for.

What is connected to J1?

PW
   

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Sergey Stalker says that ferrite rod should be "low frequency" i.e. rods from radio (magnetic antenna) are not suitable here. It is ok to use ring or some other shape core, but it should have big loss after 1MHz.
...and that seems to be a very significant detail.
   

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... there would be a possibility of the "miller" effect coming into play with the early turn off of Q4 as the gate voltage is rapidly brought to ground with the gate to drain capacitance pulling the base voltage of Q6 below ground as seen.
The gate would have to be at a higher potential than the drain, for this to happen ...and the CGD is so tiny.
Do you think that scenario is really feasible ?
   

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Vasik,

Thanks, that is what I was looking for.

What is connected to J1?

PW

J1 acts like switch to select one of the TL494 outputs.



Itsu
   

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...and that seems to be a very significant detail.

Hmmm,  are not all these ferrite rods "rods from radio (magnetic antenna)", so not suitable?
Mine is not showing the effect (from tapering of ringing without rod to ringing cutoff after 5 pulses with rod)

Itsu
   

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The gate would have to be at a higher potential than the drain, for this to happen ...and the CGD is so tiny.
Do you think that scenario is really feasible ?

Stalker talks about this negative voltage in the rk_rev2.pdf (attached) on page 15, pointing to the video (page 14 top): https://www.youtube.com/watch?v=NGiBxuLgjrw  at 5:39 min.

It reads:

5:39
several resistors, pay special attention to resistors
that bias the gate of the transistor of p conduction
because transistor of p conduction needs to control of negative
voltage, and n channel transistor we control with
positive potential, with them all easier,
for p channel it is necessary make a system that
controls with negative voltage
and this one our divider, we will be interested in which in ultimately
determines consumption and stability of this circuit
6:33
the divider on the gate of the transistor
irf4905 is selected in such a way that
here the negative voltage was about 14.7volts
it is the same as n channel transistors can be controlled by voltage up to 20 volts
but most importantly, this divider is chosen
so so that this transistor during its operation lengthened the time of signal

etc.


Itsu
   

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Vasik,

Thanks, that is what I was looking for.

What is connected to J1?

PW

J1 just a jumper to select push pull signal on which kacher syncronizing.
1-2 or 2-3 should be shorted.

Vasik



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Hmmm,  are not all these ferrite rods "rods from radio (magnetic antenna)", so not suitable?
Mine is not showing the effect (from tapering of ringing without rod to ringing cutoff after 5 pulses with rod)

Itsu

Yes, Stalker says it should be LF ferrite.
Alexeev says that number of turns need to be tuned, so that voltage on antenna have 90 degrees shift in relation to kacher coil.

Vasik


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The gate would have to be at a higher potential than the drain, for this to happen ...and the CGD is so tiny.
Do you think that scenario is really feasible ?

When the BJT is turned off as it is in the scope traces before any base drive is applied, the gate of Q4 is high, Q4 is turned on and the drain therefore is at near ground potential.  So in this state, the gate is at a higher potential than the drain and both the gate to source and gate to drain capacitances are charged.  The next falling edge on the gate of Q4 (which leads the turn on of Q5 that supplies the base drive current) dumps this energy through the drain into the base connection of Q6 and the bulk substrate diode of Q4.

For the IRF3205, the gate input capacitance is typically 3247pf (!) at zero gate volts and this value being non-linear will decrease with higher gate voltage.  The reverse transfer capacitance is typically 211pf.   

The capacitance and inductance of the circuit during this point in time are both relatively small as indicated by the high resonant frequency seen.

Regards,
Pm
   
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Many thanks to everyone that replied to my connection question.

This driver circuit is quite strange, convoluted at best.

Food for thought...

Apparently, Q4 is used to gate on and off the oscillations generated at Q6 (and open the collector of Q6).  The divider formed by R17 and R18, in concert with D1, apparently bias Q6 such that an oscillation is produced by feedback from the "antenna" when Q5 is on and Q4 is off.

Other than the very brief period (determined by propagation delay) following Q4 turn-off, when Q4 and Q5 are both turned off for 150ns or so (and the base of Q6 is held low by R18) one has to wonder if Q5 is needed at all (i.e., D1 connected directly to the supply rail). 

However, someone apparently went to a lot of trouble to add the propagation delay and slow turn-on and even slower turn-off of Q5.  Perhaps the slow turn on of Q5 following Q4 turn-off was needed to ramp-up Q6 turn-on through a linear region to ensure oscillation start-up.

The question I now have, after the pin 1 and pin 7 mix-up discussions, is whether it is actually intended that Q5 remain on for the longer period or if Q4 is to remain on for the longer period.

It would seem to me that the circuit would oscillate during the entire Q5 on/Q4 off period.  Perhaps it is the Q5 on time that is intended to be the shorter time period, allowing the circuit to briefly oscillate by active means following a much longer period, when Q4 is turned on and Q6 is turned off and with an open collector, allowing these oscillations to ring down.  If this is so, Q4 would be turned on for most of the time. 

Someone let me know if I am not comprehending this correctly.

I originally thought that the drive coil was to be hit with just a quick pulse and then allowed to ring down.  This circuit does not appear to do that.  It would appear moreso to be a gated oscillator. 

Are the outputs at J3 and J8 not being used at this time?

PW
« Last Edit: 2021-05-11, 18:07:37 by picowatt »
   

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PW,

This driver circuit is quite strange, convoluted at best.
Yes, in a way.
AFAIK Sergey is not electronic professional, schematic can be optimized and improved.
Purpose of this schematics is to give possibility to create a working prototype of device. Nothing else.
In my opinion for real use it should be reworked completely.

Quote
The question I now have, after the pin 1 and pin 7 mix-up discussions, is whether it is actually intended that Q5 remain on for the longer period or if Q4 is to remain on for the longer period.
Please check attached screenshot (top right corner). There shown signals of Q4 Q5.
First Q5 apply bias to base of Q6 thru resistor and diode and then Q4 opened.

Quote
It would seem to me that the circuit would oscillate during the entire Q5 on/Q4 off period.
yes, you right

Quote
I originally though that the drive coil was to be hit with just a quick pulse and then allowed to ring down.  This circuit does not appear to do that.  It would appear moreso to be a gated oscillator. 
Yes, you right. This is gated oscillator. Gated kacher.
There are two options: Tesla coil driver (module 3 as Itsu call it, it gives multiple pulses)
 and this gated kacher (module 4).
I selected kacher for this PCB in a hope that it will be easier tune it.

Quote
Are the outputs at J3 and J8 not being used at this time?
yes, they are used both, they are two push pull switches.

Vasik


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So, the coil assembly is being driven by pulses via the push-pull outputs while at the same time (with adjustable delay) the Q6 oscillator is being gated at the same rate as the push-pull outputs.  Is this correct?

What is the relationship of the frequency of the oscillations produced during the ring-down following excitation by the push pull outputs to the frequency of the oscillations produced by the Q6 gated oscillator?  ( i.e., is there supposed to be a particular phase or harmonic/numerical relationship between the two?)

PW



   

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So, the coil assembly is being driven by pulses via the push-pull outputs while at the same time (with adjustable delay) the Q6 oscillator is being gated at the same rate as the push-pull outputs.  Is this correct?
Yes, kind of. Push pull drives directly gradient coil and also through serial LC circuit.

Quote
What is the relationship of the frequency of the oscillations produced during the ring-down following excitation by the push pull outputs to the frequency of the oscillations produced by the Q6 gated oscillator?  ( i.e., is there supposed to be a particular phase or harmonic/numerical relationship between the two?)
Yes. Without details it looks like this: Gradient coil tuned to 1/2 wave resonance (e.g. 1.2Mhz) and push pull to it's sub-harmonic (e.g. 30Khz). Tesla coil tuned to have 1/4 wave resonance at 1.2Mhz and give burst of pulses at the top of sine in LC circuit (pls. see attached picture).

For more detailed instructions how to find sub-harmonics and description how system works in general scroll this topic few pages back.

Vasik

PS there are many other tuning details, I just think that it better go step by step.


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PW,  see also Vasik his reply drawings.

see this diagram where J2 is connected to:




J4 is 24V input
J3 and J8 are push Pull (from delayed TL494) connectors going to the Yoke coils, see this diagram:



The additional terminal is added by me to get and extra inverted output of the 4093 to drive an optional MOSFET (instead of transistor) to drive the kacher.
see this diagram:
 


Itsu

Itsu,

In the "Modules Connection" drawing, are those two 12VDC to 240VAC inverters?
Are the 12 volt inputs from the 12V battery (going to the inverter terminals
marked + and -) actually meant to be connected in parallel to both inverter inputs?
I assume the positive from the battery was also meant to feed J4.  If so, the drawing
appears to be incorrect.

As well, it appears the pair of 240VAC inverters have their AC outputs connected in parallel.
Are these inverters (hopefully) operating synchronously?  The inverter AC outputs
appear to be feeding a 10-47uF cap and the +/_ terminals of a bridge rectifier with its AC
terminals feeding the indicated coil.  This just isn't making any sense to me.

What am I missing?  Is this section related to the inverters drawn incorrectly?

Confused...

PW
   

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Itsu,

In the "Modules Connection" drawing, are those two 12VDC to 240VAC inverters?
Are the 12 volt inputs from the 12V battery (going to the inverter terminals
marked + and -) actually meant to be connected in parallel to both inverter inputs?
I assume the positive from the battery was also meant to feed J4.  If so, the drawing
appears to be incorrect.

As well, it appears the pair of 240VAC inverters have their AC outputs connected in parallel.
Are these inverters (hopefully) operating synchronously?  The inverter AC outputs
appear to be feeding a 10-47uF cap and the +/_ terminals of a bridge rectifier with its AC
terminals feeding the indicated coil.  This just isn't making any sense to me.

What am I missing?  Is this section related to the inverters drawn incorrectly?

Confused...

PW

PW,

There are two 220v AC - 12v DC PSU modules used for looping.
Inputs are connected in parallel, outputs in series to provide 24v.

Tesla coil powered from 12v through DC DC converter (12 -> 50..200v)
This allow system start from one 12v battery.

BTW If you read rk.pdf you will find pretty detailed explanation of all these details.

Vasik

PS schematic might be not optimal, but it is correct and makes perfect sense for me.


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The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
   
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PW,

There are two 220v AC - 12v DC PSU modules used for looping.
Inputs are connected in parallel, outputs in series to provide 24v.

Tesla coil powered from 12v through DC DC converter (12 -> 50..200v)
This allow system start from one 12v battery.

BTW If you read rk.pdf you will find pretty detailed explanation of all these details.

Vasik

PS schematic might be not optimal, but it is correct and makes perfect sense for me.


So those are 220VAC to 12VDC converters (not inverters, my bad).

Why are the AC inputs to the converters being fed DC by a somewhat filtered bridge rectifier?

What is the component labeled "N" across the AC inputs?

PW
   

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PW,

So those are 220VAC to 12VDC converters (not inverters, my bad).
Why are the AC inputs to the converters being fed DC by a somewhat filtered bridge rectifier?
What is the component labeled "N" across the AC inputs?

These are standard, cheap power supplies.
They have diode bridge inside on the input (like most modern electronic PSU), but they work fine from DC also.
It is just a cheap and easy solution.

"N" I think marks load e.g. incandescent lamp or heater

Vasik


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I have removed the inductor (62uH) and added some layers of cardboard first then rewound the inductor again, but it gained only a few uH's (66uH).
Adding more cardboard does not further increase the inductance, so i will leave it at this.

Grenade 37.5m long, 143uH,
inductor 9.37m long, 66uH.

It seems that my Kacher coil is oscillating around 1.6Mhz, so a little high as the grenade 1st resonance point is around 1.22Mhz.
My kacher coil (secondary) is wound in a spaced way (1:1) CW with the top a few turns reversed, so CCW.
Not sure this reversing is needed, but was the buzz word a few years back.

Guess i will wind a new secondary also spaced 1:1 but without the reversal at the top and longer wire to get to the 1.22Mhz oscillation frequency.



Itsu
   

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Guess i will wind a new secondary also spaced 1:1 but without the reversal at the top and longer wire to get to the 1.22Mhz oscillation frequency.

Itsu,

in youtube comments Sergey answered questions, he says that he has Tesla coil 12cm width winding with 0,75mm wire which is approx. 25m and 160 turns, with resonance at 4.6Mhz (calculated with calculator, which is "suspiciously" matching second resonance on his gradient coil).

Alexeev says in some video that Tesla should be half length of gradient coil which gives approx. 20m

Probably we will have to make some trials which works better...

Vasik

PS https://www.youtube.com/watch?v=v6FrGTF731o


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The only way of discovering the limits of the possible is to venture a little way past them into the impossible.
   

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This driver circuit is quite strange, convoluted at best.
You are not kidding !

However, someone apparently went to a lot of trouble to add the propagation delay and slow turn-on and even slower turn-off of Q5.  Perhaps the slow turn on of Q5 following Q4 turn-off was needed to ramp-up Q6 turn-on through a linear region to ensure oscillation start-up.
Indeed, without this 150ns delay, the entire driver could be simplified.

The question I now have, after the pin 1 and pin 7 mix-up discussions, is whether it is actually intended that Q5 remain on for the longer period or if Q4 is to remain on for the longer period.
I don't know what the author's intention was with the propagation delay of Q5 but I am certain that pin 1 was intended to go high first and fall down first.

It would seem to me that the circuit would oscillate during the entire Q5 on/Q4 off period.
If it can oscillate during the entire period then the entire base driving circuit could be simplified to something like this:



I originally thought that the drive coil was to be hit with just a quick pulse and then allowed to ring down.  This circuit does not appear to do that.
It would appear more so to be a gated oscillator. 
I agree

Someone let me know if I am not comprehending this correctly.
I think your analysis is correct.  You may want to add the following point made by Vasik041 to your considerations:

...,so that voltage on antenna have 90 degrees shift in relation to kacher coil.
« Last Edit: 2021-06-19, 00:29:21 by verpies »
   

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What are the signals on pins 1 & 7 of the IR2113 ?
Is this IC the IR2113 or IR2113S ?

Also, how does that base signal look with the antenna wire disconnected from the base and the collector connected to +V with a non-inductive resistor*?

*Large enough as not to exceed the transistor's maximum collector current (IC).

verpies,

just to be clear, what you called "the antenna wire" in the above quote, is in fact the secondary bottom wire of the kacher.
"The antenna" in this setup refers to the wide 5 turns coil across the inductor coil on the right side of my last picture from  post #420

Itsu 
   

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Yeah, I call it "antenna wire" because it is a coiled wire connected only at one end.
Should I call it "coiled antenna" from now on ?

Why not call it Kacher secondary bottom wire (ksbw)   >:-)
   
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