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2021-12-01, 02:54:26
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Author Topic: Dally, Shark & Ruslan workbench  (Read 72376 times)

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I did not check the schematic, so don't take my silence as a sign that it is OK.

Actually, I do not understand why this circuit is configured that way at all, i.e.: a 230V, 15A BJT being driven by several MOSFETs.
Why not use one high-power N-ch MOSFET being driven by a specialized gate driver (e.g. the UCC27511), like it is done usually?

Also, I do not understand why the low/high side driver (IR2113) appears to drive two N-Channel MOSFETs (Q3 & Q4) which have their both sources grounded. 
Alas, the entire purpose of a high-side driver is to drive the gate of an N-channel MOSFET's, which typically has its source connected to a high voltage rail ( i.e.: not grounded ! ) in order to completely avoid using a P-channel MOSFET (like the Q5*).

The high half of the IR2113 driver simply:
1) connects the HO output to the VB input when the the HIN input is high (and SD input is low).
2) connects the HO output to the VS input when the the HIN input is low (or SD input is high).
...while the VS and VB inputs are at voltage levels which are typically well ABOVE ground (also VB > VS+8.6V )**.

Below is a diagram of this typical connection from the IR2113's datasheet:



The only advantage of the IR2113 driver (which are two drivers in one package: a low-side driver and high-side driver) over the UCC27511 driver, is its duality and the ability to pull up and pull down the load solely with N-ch MOSFETs, while an N-ch MOSFET driven by the single UCC27511 driver can only pull down the load.
By connecting together the COM and VS pins of the IR2113, that "push-pull" advantage solely with N-ch MOSFETs, is nullified.

* this also makes the blocking diode on its drain unnecessary (re.: SR510).
** which is why I wanted to see these voltage levels simultaneously on both output pins.



I agree,  and there is such a MOSFET circuit presented by Stalker, see here:





But it seems easier to use the Transistor drive circuit to get the required results.

Itsu
« Last Edit: 2021-05-09, 21:48:15 by Itsu »
   

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Ok,  here the IR2113 pin 1(blue)  and pin 7 (yellow) signal / relations:
So these signals are moving between the same two voltage levels, despite the IR2113 being especially designed for 4 different voltage levels and these pulses overlap (are both high at the same time) for ~100ns , which means that the base of the BJT is both pulled up and down during that time (minus Q5 delay) *.
There also should be a similar time period where both of these signals are low (not shown on your scopeshots) and during that period the base of the BJT is not pulled up nor down, so it is more free to oscillate according to the signal coming from the antenna wire.

* If the resistor R17 was absent, then during that time a high shoot-through current would flow and Q4 and Q5 would become damaged.



I agree,  and there is such a MOSFET circuit presented by Stalker, see here:
But that circuit has different features. For example it does not feature a dead period during which the signal from the antenna wire can drive the main transistor unencumbered.

I've been considering whether the IR2113 is strong enough to drive the base of the BJT alone without deleting features. To answer that I would need to know the amplitude of the current pulses flowing in the drains of Q4 and  Q5.  (just the current amplitudes - not their temporal relationship).

But it seems easier to use the Transistor drive circuit to get the required results.
The completely different impedance of the BJT's base compared to the impedance of the MOSFET's gate are also different features, which matter to the signal picked up by the antenna wire a lot.
   

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First thing i did was swapping pins 1 & 7 of the IR2113 and measuring again the base of the transistor (purple) which looks much better now.

Screenshot shows:

green:  kacher output (probe near top kacher coil)
purple: base signal Transistor
yellow: pin 7 IR2113
blue:   pin 1 IR2113





I still have 5V on the collector / primary kacher coil, but no visible current flowing on the 1A analog meter (300mA yesterday).

I just cut the traces from IR2113 pins 1 & 7 short to the chip and rewired to correct points.

Not sure if i easily can measure the Q4 and Q5 drain currents as the pcb is compactly set up.


Itsu

 
   

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First thing i did was swapping pins 1 & 7 of the IR2113 and measuring again the base of the transistor (purple) which looks much better now.
I just cut the traces from IR2113 pins 1 & 7 short to the chip and rewired to correct points.
Not sure if i easily can measure the Q4 and Q5 drain currents as the pcb is compactly set up.
Itsu

Looks good  O0


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Not sure if i easily can measure the Q4 and Q5 drain currents as the pcb is compactly set up.
Can you get at the current in the big BJT's base lead ?
   

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This is the base voltage (27mVpp) across a 0.1 Ohm inductionfree resistor, so 270mApp:



Itsu
   

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This is the base voltage (27mVpp) across a 0.1 Ohm inductionfree resistor, so 270mApp:
...but your scope says "Peak-Peak: 339.8mV" so  shouldn't it be 339.8mVp-p /0.1Ω = 3.398Ap-p ?
   

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Well, thats for the max peak to peak signal it sees, but these larger spikes are i think the feedback from the kacher ringing signal (the green signal from the earlier screenshot)
So i put horizontal cursors for measuring the signal from which i think must be the voltage/current

   

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So if we assume that 3.398Ap-p current as the worst scenario then it means that the source and sink currents are half that value or 1.7A, which is well within the capabilities of the IR2113.

...and there is such a MOSFET circuit presented by Stalker, see here:
...and do you have the UCC37322 driver used in this circuit ?
   

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Here i have raised the Collector / primary coil voltage from 5V to 12V and measured the kacher output (green trace) and again the base voltage/current across a 0.1 Ohm resistor (yellow trace)
The delta voltage is now 34mV pointing to 340mA:




Quote
...and do you have the UCC37322 driver used in this circuit ?

I did build that MOSFET Kacher drive circuit on a breadboard, but did not use the MOSFET nor MOSFET driver as i only wanted to see the pulses created by that circuit.
So there is a difference between the Transistor Kacher drive circuit and the MOSFET Kacher drive circuit in that the MOSFET circuit produces a burst (4 a 5) of small pulses pulsing the Kacher, while the Transistor circuit relies on the Ringing to produce 3 a 5 pulses as i understand.

Here the video at the time i started to explain this MOSFET drive circuit: https://youtu.be/SQn-8hZSGhk?t=164   then.

Itsu
   

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Itsu,

I think that pins swapped in PCB, please check.

Regrading tuning of the antenna in your video, here is Alexeev's video transcript explaining how it should look like.
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.

Vasik

Vasik,

concerning your s_tuning.pdf,   some questions:

1:01 this 2.2nF tuning cap, where should it go?  (across the primary of the Kacher coil)?

2:04 Where do the (26) HER108 / hvr1x3 diodes with parallel 330K-470K diodes go? (Kacher / antenna output to ground to create unidirectional pulses?)

2:48 With 5 (or 3) pulses he means the the amount of ringing pulses from the Kacher?

3:03  with "one coil 16KHz and second coil 8KHz, he means the grenade and Inductor?

Itsu
   

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So there is a difference between the Transistor Kacher drive circuit and the MOSFET Kacher drive circuit...
Of course there is, because when the final MOSFET is OFF, it still conducts in one direction through the body diode.  The BJT does not conduct in either direction when it is off.
Also, the base of the BJT presents a very different impedance to the antenna compared to the gate of a MOSFET.

FYI: MOSFET driver chips can drive BJT bases directly, ...and they can do it in a very well controlled 3-state manner in which the signal from the antenna is allowed to influence the base of the BJT (during the High-Z state) without being loaded by the base driver.
« Last Edit: 2021-05-10, 01:50:42 by verpies »
   

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concerning your s_tuning.pdf,   some questions:

Quote
1:01 this 2.2nF tuning cap, where should it go?  (across the primary of the Kacher coil)?
yes, across kacher's primary
this can help increase output voltage if needed

Quote
2:04 Where do the (26) HER108 / hvr1x3 diodes with parallel 330K-470K diodes go? (Kacher / antenna output to ground to create unidirectional pulses?)
Please see attached schematic. The diode in a red circle.
It creates offset on the gradient coil (as I understand).
This is one of the "secret" details, usually not mentioned (and could be shown wrongly).
It is one of the possible modifications of the circuit.

Quote
2:48 With 5 (or 3) pulses he means the the amount of ringing pulses from the Kacher?
yes

Quote
3:03  with "one coil 16KHz and second coil 8KHz, he means the grenade and Inductor?
Yes.
This is again one of possible modifications.
Stalker says that gradient coil capacitor is not resonant.
I guess you will need find in practice which one works better.

Vasik


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The difference between Kacher (module 3) and Tesla coil (module 4)
is that Tesla coil module creates pulses for the coil itself
(and so requires very fine tuning)
but kacher module just makes a modulation signal, coil oscillations created by transistor (Q6).

Adjusting R17 and R18 you set Q6 current. This will determine how much power it will put into oscillations.

Vasik


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Thanks,   so we still have severall "possible modifications" and "secret details, usually not mentioned (and could be shown wrongly)".

Itsu
   

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Thanks,   so we still have severall "possible modifications" and "secret details, usually not mentioned (and could be shown wrongly)".

Itsu

Yes :) You know, system gradually evolved over last 10 (probably) years .
Also level of paranoia is very high around such systems.
I am sure that even here there are many people who don't want such systems to be freely available  :-X

Vasik


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The BJT does not conduct in either direction when it is off.


Actually, this is not correct.  The NPN for example (see image below) has a PN junction between the collector and base as shown.  This junction will conduct when the collector is taken more negative than the base voltage and if taken below the zener breakdown of the reverse emitter/base junction, there will be conduction between the collector and the emitter.

regards,
PM
   

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Actually, this is not correct.  The NPN for example (see image below) has a PN junction between the collector and base as shown.  This junction will conduct when the collector is taken more negative than the base voltage and if taken below the zener breakdown of the reverse emitter/base junction, there will be conduction between the collector and the emitter.
You are correct. The base junction will conduct and it will affect the transistor's conduction when it breaks down.
I did not consider these atypical operating conditions - only the typical ones.

Whether the BJT is operated in these extreme regimes or not, a final stage based on a single MOSFET will conduct differently...and two MOSFETS connected in series will conduct differently, too, when their body diodes never conduct simultaneously.
At this point, I am not recommending putting 2 MOSFETs connected in series in place of the BJT even if that would result in a better-controlled conduction profile, but I think that its present 3-state base driving circuit is too complicated and too inflexible with regards to allowing the operator to adjust the duration of each of these 3 states (high, low, high-Z). 

I assume that the High-Z state is important to allow the signal form the antenna wire to jerk the BJT's base unencumbered - if it weren't, the 2-ch driver (IR2113) would be redundant in the base driving circuit (...and the delayed pulses applied to its 2 channels, too).
   
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Vasik
Quote
 I am sure that even here there are many people who don't want such systems to be freely available  :-X
End quote

Then those persons are in the wrong forum... and will hopefully be very disappointed!!

Respectfully
Chet K
   

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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).


Not sure this test is still needed, but here i have the antenna wire disconnected from the base and the collector connected to +12V with a non-inductive resistor (350 Ohm 1%)

Severall screenshots taken,

yellow = collector voltage
green  = base current
blue    = base voltage

1st is overview, 2nd is expanded time base, 3rd is with increased base current sensitivity.








Itsu
   

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...the antenna wire is disconnected from the base and the collector is connected to +12V with a non-inductive resistor (350 Ohm 1%)
yellow = collector voltage
green  = base current
blue    = base voltage
@Partzman
Where do you think the negative voltage on the base comes from?

   
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@Partzman
Where do you think the negative voltage on the base comes from?

It has to be coming from the driver IMO.  If you or Itsu can point me to the correct schematic used to produce these waveforms, then we should be able to tell for sure!

Regards,
Pm
   
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Can someone please post a diagram of what is connected to J1, J2, and, if used, J3 and J8.  If it has already been posted, perhaps a post number. 

There is mention of an "antenna" connected to the base (Q6?).  Is this a real connection to the base not shown in the schematic or is this a connection via J2?

Trying to follow along...
Thanks,

PW

   

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If you or Itsu can point me to the correct schematic used to produce these waveforms, then we should be able to tell for sure!
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.

   
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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.

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 

   
   
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