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Author Topic: Dally, Shark & Ruslan workbench  (Read 53556 times)

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I thought the purpose of turning Q6 on continuously was to allow you to adjust the collector current to around 150ma.
...or max gain.

If you are going to experiment with varying the Q6 base current, I suggest replacing R17 with a fixed 1K resistor in series with a 10K pot
That's a good idea IF Itsu wants to DESOLDER resistors from the PCB.

(R18 is a minor player, leave it at 2.7K). 
R18 is a minor player for the base's DC bias ...but it is not so for the grounding of the coil/antenna and attenuation of its AC amplitude at the base.

This will allow you to vary the base current from approximately .9ma to 6.5ma.
That's only 0.4% of the maximum base current (1.5A)

To achieve collector currents much above above 200ma you will need to reduce the value of your 100R load resistor (or increase the 24 volt supply) 
50Ω would provide better match for the SA's input.  If he chooses to use it.

All numbers and values are approximate, both Vbe and Hfe vary significantly with current and temperature (and between devices).  With no emitter degeneration, collector current will vary considerably as Q6's temperature varies.   
Yes :(  ...such is the nature of this circuit.

Q6 is a BJT, not a FET.  Base bias should be discussed in terms of base current, not base voltage.
Quite right, however measuring the base current means breaking into the PCB

It would be nice to know what and how this circuit is supposed to perform.  That being said, making adjustments using the FG and an arbitrary load may not equate to the desired operating parameters when connected to the rest of the circuit.
That's what I am afraid of the most, too.
However the experiments above will yield much more information about the BJT's behavior in this circuit than we had up to date.
Dummy load keeps his test gear safe.

Again, I thought Vasik said to set the collector current to around 150ma,...
I am hoping that these experiments confirm that this amount of bias is the one at which the max gain occurs, too.
   

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After finding the best bias for the BJT's AC gain, I envision the next experiment which is the same as the 1st one but with the addition of the 2nd channel of the FG driving the tC point with 1Hz square wave so we can observe the variable gain of the BJT as a gated linear amplifier.
   

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Here is an old PCB  I have modified to simulate Itsu's circuit.

I'm feeding it with 20khz 50/50 sqr wave, I’m using a 35 volt bulb as output, The driver stage is fed by 27volts
dropped down to feed Q5 and Q3 and Q4 and the IR 2110 with 15 volts the scope probe is on Q6 collector.

The scope shot is also 20 khz with a negative pulse of 8.4 usecs and  27 volts P-P

also included the 2N5200 data for your reference.

PS i also had a problem with some of the driver Fets, you need to watch the gate turn on voltage of some
of the Fets as the IR chip has a problem switching on and off modern versions of the IR3205

Regards Sil

PS at the end of the day this is just a one cycle pulse width device on one of the Blaz TV  docs it shows
to break out of this GAME you need to creat a spiraling vortex, any ideas ?  one guy who does just that
https://www.youtube.com/watch?v=-FuJ5mOV6Vg
   
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After finding the best bias for the BJT's AC gain, I envision the next experiment which is the same as the 1st one but with the addition of the 2nd channel of the FG driving the tC point with 1Hz square wave so we can observe the variable gain of the BJT as a gated linear amplifier.

IMO, the operation is just what you describe that is, a gated linear amp.  If it was intended to be class A linear, then why the switched base resistor?  If this is the case, then you would possibly have one of two possible operating modes. 

One, bias the 2SC5200 toward cutoff or IOW small base current and then allow the positive half cycle of the HF feedback from the antenna to "turn on" the base of the 2SC5200 or two, bias the base with enough current to place the Q point toward the bottom of the load line or IOW near saturation but not quite, and then the negative half cycle of the HF feedback would "turn off" the base of the transistor.  Either mode would modulate the collector current.

Another consideration could also be the difference between the large signal current gain hFE which would determine the operating point on the load line and the small signal current gain hfe which would be the AC current gain.  The 2SC5200 data sheet does not spec hfe and usually that means it is nothing to brag about but the high frequency rolloff is 30Mhz typical so it possibly might have reasonable HF current gain!

Regards,
Pm
   

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IMO, the operation is just what you describe that is, a gated linear amp.  If it was intended to be class A linear, then why the switched base resistor?  If this is the case, then you would possibly have one of two possible operating modes. 

One, bias the 2SC5200 toward cutoff or IOW small base current and then allow the positive half cycle of the HF feedback from the antenna to "turn on" the base of the 2SC5200 or two, bias the base with enough current to place the Q point toward the bottom of the load line or IOW near saturation but not quite, and then the negative half cycle of the HF feedback would "turn off" the base of the transistor.  Either mode would modulate the collector current.

Another consideration could also be the difference between the large signal current gain hFE which would determine the operating point on the load line and the small signal current gain hfe which would be the AC current gain.  The 2SC5200 data sheet does not spec hfe and usually that means it is nothing to brag about but the high frequency rolloff is 30Mhz typical so it possibly might have reasonable HF current gain!

Regards,
Pm
The 2N5200 I have has an HFE of 90 some are higher if your buyimg obsolite stock The minimum is quoted at 50 hfe
with a maximum transition freq of 30mhz I wonder how sharp that looks on a scope ? Enjoykin recomends a device in the VHF range.
 Sil

   

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   I have not heard of that being the case, as the purpose of this particular Kacher device, and its antenna coil. Maybe I'm confused about that, as well. But, the idea is that the HV and HF from the kacher circuit is used as an interuptor (shock wave), to impede the induction circuit signals. And not to directly add more gain or a higher output due to the addition of its HV, HF signals. So, it's purpose is not your normal every day type of HV circuit that we would normally expect, but an interuptor signal, instead.  I mention this for those of you that are not familiar with this device, or how it's supposed to work.

   NickZ
   
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...or max gain.

Or not...  Why such a contorted circuit overall for just a gated common emitter amplifier? 

Quote
R18 is a minor player for the base's DC bias ...but it is not so for the grounding of the coil/antenna and attenuation of its AC amplitude at the base.

When Q6 is conducting, Q6's base impedance is going to be much lower than any reasonable values for R17 or R18 and will, for the most part, determine the "input" impedance.  When Q6 is not conducting, the base is held very close to ground by Q4's on resistance.

Quote

That's only 0.4% of the maximum base current (1.5A)

And your point?  I doubt many applications run anywhere near 1.5 amp of base current.  Half that would be a lot.  The original R17=3.3K operated Q6 at about 3.8ma of base current.

Quote
50Ω would provide better match for the SA's input.  If he chooses to use it.

Using the SA, do we adjust for the "cleanest signal" or something "harmonically rich"?  I don't think we know.

Quote
Quite right, however measuring the base current means breaking into the PCB

My point was that BJT's are current controlled devices, not voltage controlled like a FET.

However, base current can be measured as the Vdrop across R17 divided by R17's value.  R18 shunts 200ua to 300ua away from the base which is minimal at the base currents being used, but it too can be accounted for in the base current measurements/calculations if desired.

I used 700mv as both the forward voltage of D1 and the Vbe of Q6 in my rough calculations.  With R17 at the original 3.3K value, and using Hfe=80, I get around 310ma of collector current.  With R17=8.2K, that works out to around 112ma of collector current.  Both calculated values are a bit low (310ma calculated versus 350ma measured and 112ma. calculated versus 130ma measured).  I suspect the the use of Hfe=80 is a bit too low for Itsu's Q6.  Using Hfe=95 instead of 80 pushes the calculated numbers closer to the measured values.

PW
« Last Edit: 2021-06-16, 22:44:41 by picowatt »
   
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PW,


Yes, it was, and because of being able now to turn Q6 on continuously i was able to set it to its present 130mA by changing R17 to 8.2K.

But.... i noticed that after doing so, the power into the Kacher had dropped to almost nothing, even with 24V on the collector.

Itsu,

What prompted you to change the value of R17 from that of the schematic to begin with?  If the posted schematic supposed to "work", why deviate?

We discussed this circuit many pages back, and it looked to me then like Q6 is biased into a linear region to allow it to act as a gated oscillator.  The past confusion over whether HO or LO was supposed to drives Q4 is still a bit concerning.  I am not 100% convinced it is now connected as it should be.  One must consider why the designer of this rather contorted circuit felt the need to not use the high side driver internal to the IR2110, but instead added a discrete high side driver .  As well, why is there a need for three gates worth of propagation delay at one of the IR2113 inputs? 

Quote
So the discussion now is if this 130mA is the correct value for the kacher to work properly by increasing the collector voltage to 100 - 150V, or that we should be looking for another M.O. of this kacher by what verpies called "linear amplification".

Linear amplification of the (ringing) signal from the kacher / antenna via its secondary coil bottom wire back to the base of the transistor which needs another setting / ratio of the R17 / R18 bias resistors.


Thats what i am trying to do now by making R17 (R18) variable by the way you also mentioned.

That's fine, but do not think of R17 and R18 as acting as a voltage divider, they do not.  R17 sets Q6 base current.  Think of the base emitter junction of Q6 as being just a standard silicon diode.  Once sufficient forward voltage is applied to cause that diode to conduct (.6V to .7V), increasing the current through the diode (or the base emitter junction) by decreasing R17, will only vary the forward voltage by a small amount.  At higher currents, the diode's forward voltage (or Vbe) may increase to a volt, or even a bit more, but at the base currents proposed in the provided schematic, Vbe will be around .6V to .75V (note Vbe is temperature dependent as well).  Base current times the transistor's current gain determines the collector current.

Consider adding the fixed resistor/variable resistor combo I mentioned to replace R17.  Connect it all up as you had previously and vary the base current while monitoring the effect various base currents have on the circuit operation (as originally designed).   

Quote
Parallel to that i will use the present (130mA) setup and increase the collector voltage to 100 - 150V to see if that gives the desired effect as mentioned by Vasik:   "radiant effects (DC on metallic surfaces, white sparks)"  / "create shock waves".


Regards Itsu

And Itsu, thanks for all the data and videos you have shared with us.  Your time and efforts on this build are greatly appreciated. 

PW
« Last Edit: 2021-06-17, 06:03:02 by picowatt »
   

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PW,




Quote
Itsu,

What prompted you to change the value of R17 from that of the schematic to begin with?  If the posted schematic supposed to "work", why deviate?

We discussed this circuit many pages back, and it looked to me then like Q6 is biased into a linear region to allow it to act as a gated oscillator. 
The past confusion over whether HO or LO was supposed to drives Q4 is still a bit concerning.  I am not 100% convinced it is now connected as it should be.
One must consider why the designer of this rather contorted circuit felt the need to not use the high side driver internal to the IR2110, but instead
added a discrete high side driver . 
As well, why is there a need for three gates worth of propagation delay at one of the IR2113 inputs? 


I was prompted to change the value of R17 by a post (#852) from Vasik who wrote:

Quote
Quote
Quote from: Itsu on 2021-06-11, 20:25:55

    I pulled out U7 (IR2110) and pulled up pin 1 to +15V using a 1K resistor.
    I have a 1 Ohm 1% inductionfree resistor (csr) in the collector lead coming from the primary coil and measure 428mV across it, pointing to 428mA going through this primary.
    The 12.8V collector PS shows 360mA, so i am not sure what is the most accurate value.
    I had to remove the ground wire from the circuit as the scope probe ground lead would have caused a shortout.
    Itsu

I have similar looking voltage/current indicators from ebay, they are not very accurate.
400ma probably to high for 12v, for beginning I would suggest increasing slightly R17 so that current decrease to 100-200ma (not sure).

Vasik



Vasik had some indications that the collector current with 12V on it in continues mode should be between 100 and 200mA, so thats what i aimed for.

I also understand that the designer of this circuit (Stalker) is a "self taught" guy who's method to reach a specific goal (whatever that is here) could be somewhat unorthodox.

 

Quote
.........
Consider adding the fixed resistor/variable resistor combo I mentioned to replace R17.  Connect it all up as you had previously and vary the base current while monitoring the effect various base currents have on the circuit operation (as originally designed).   


In the light of what i wrote in my next post, i might have to build another testbed to do this testing you propose and i could also test verpies his linear amplification test setup.


Itsu
   

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Before changing the PCB by desoldering some resistors and make some of them variable etc., i decided to take a quick shot at increasing the collector voltage to the intended value of 100 to 150V in the present fixed setup (R17 / R18).

The 100V i put on the collector did briefly what it suppose to do by showing massive RF on the NE-2 neon and the near by positioned (not attached) scope probe showing the typical pulsed kacher ringing signal with severall hundreds Vpp.
I even did hear some wining sounds but not able to pinpoint it.

But not long after (10 seconds or so), the thing stopped working causing the used PS to bog down / shutdown etc.

It turns out that the 2sc5200 transistor is defective as after removal it measures 0 Ohm collector - emitter and 5 Ohms between base - collector and base - emitter. 

I don't think the transistor had the chance to became to hot that fast, so it probably was some voltage overload somewhere.

So i think i have to make another testbed (pcb / breadboard) for testing this backend setup at higher voltages and continue to test the original PCB with modified / variable resistors after replacing the transistor (as that was all there is defective looking at the signal below where the base suppose to be).


Regards Itsu
   

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I don't think the transistor had the chance to became to hot that fast, so it probably was some voltage overload somewhere.
Too much voltage or too much current ...e.g. into the base from that coil/antenna.
   

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Yes,  thats what it thought too.
   

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Yes,  that’s what it thought too.
Some time ago a guy calling him self 'Delimorto' started for a brief time about 10 posts on
one of Wesley’s many threads He mentioned the only a mere 2.5 kv was required from the Tesla coil
he also said a spark discharge was only of use for transferring energy from one coil to another.

Regards Sil
   

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Before changing the PCB by desoldering some resistors and make some of them variable etc., i decided to take a quick shot at increasing the collector voltage to the intended value of 100 to 150V in the present fixed setup (R17 / R18).

The 100V i put on the collector did briefly what it suppose to do by showing massive RF on the NE-2 neon and the near by positioned (not attached) scope probe showing the typical pulsed kacher ringing signal with severall hundreds Vpp.
I even did hear some wining sounds but not able to pinpoint it.

But not long after (10 seconds or so), the thing stopped working causing the used PS to bog down / shutdown etc.

It turns out that the 2sc5200 transistor is defective as after removal it measures 0 Ohm collector - emitter and 5 Ohms between base - collector and base - emitter. 

I don't think the transistor had the chance to became to hot that fast, so it probably was some voltage overload somewhere.

So i think i have to make another testbed (pcb / breadboard) for testing this backend setup at higher voltages and continue to test the original PCB with modified / variable resistors after replacing the transistor (as that was all there is defective looking at the signal below where the base suppose to be).

Itsu,

Oh oh, more sacrifice for FE.
I wrote "carefully increase voltage", not just put 100v there :)
During first experiments, while you don't know properties of your coils, you need control current and temperature, voltage on the collector. Start with low voltage and gradually increase it.

Vasik


---------------------------
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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Yeah i know, but with my dual PS unable to deploy i am somewhat limited with my voltages.

I will see if i can rebuild my variac driven, isolated from mains PS which i had used before.

Itsu
   

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Yeah i know, but with my dual PS unable to deploy i am somewhat limited with my voltages.

I will see if i can rebuild my variac driven, isolated from mains PS which i had used before.

Itsu

But you said that you have DC-DC converters, why not use one of them ?

Vasik


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yes,  a 100V to 250V output converter but 100V was already to much  :(
   

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yes,  a 100V to 250V output converter but 100V was already to much  :(

I sure we can modify it or construct something which gives proper voltage.

Vasik


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Transistor replaced and things look OK again, but looking at the base signal with only 12V on the collector we see already an almost +2V peak there.

Itsu
   
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Transistor replaced and things look OK again, but looking at the base signal with only 12V on the collector we see already an almost +2V peak there.

Itsu

Itsu,

If you can, please post a scope shot with one channel connected to LO, one channel connected to HO, and one channel connected to the base of Q6 (all DC coupled).  Trigger on rising edge of LO.

Thanks,
PW
   

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PW,

i already have such a screenshot, see:  https://www.overunityresearch.com/index.php?topic=3926.msg91628#msg91628

but i will redo this tonight.

Itsu
   

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... I more or less asked the active members of the group to do this and got nothing!
...but that measurement has already been done.
   

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AlienGrey,

I more or less asked the active members of the group to do this and got nothing!

I am building my setup now, so can't answer with scope traces immediately.

Vasik
« Last Edit: 2021-06-18, 12:39:57 by AlienGrey »


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Transistor replaced and things look OK again, but looking at the base signal with only 12V on the collector we see already an almost +2V peak there.

Itsu,

It's just 0.7V as supposed to be.
Those high peaks coming from collector through parasite capacitance.

Vasik

PS if you worry that there could be too much voltage you can put diode from base to ground.


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...but that measurement has already been done.
Great! then i will have my statment back, so what frequency and what are the pulse rising and fallind widths ?

« Last Edit: 2021-06-19, 12:43:34 by AlienGrey »
   
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