Hi Selfonlypath

No idea on this one   :-/
Suspect that the bigger globe needs more power due to the increased distance between electrode and glass.
Also the resonance parameters of 5" globe might be quite different from 3.5"

I had a look at and
Nice job, seems this is a new step in your ZPE quest   :

What is the point of replacing Mosfets by IGBT's in your new setup ??

Quote:

The flyback transformer does trigger the base of the NPN D882P transistor; the system naturally oscillates at 20kHz

Hey kas, Since i only have deconstructed & modified 5" and 8" plasma globe, i've just bought the small 3" globe that you've been playing. As i mentionned before, both 5" or 8" have their own IC oscillator hence not based on any signal coming from flyback trafo. One reason I'm interested to play with this small plasma globe is your above remark quoted. Is it possible for you to detail more precisely how it self-oscillates, the precise role of the flyback trafo, does some plasma energy inducted back signal is fed to maintain the oscillations. Any detailled info on this self-osciallting woudl be appreciated so i could save analysis & experimental time. Albert  
 

Hi Selfonlypath,
Please refer to 1st post schematic
The feedback signal is a "normal" voltage generated by an additional coil within the HV transformer. This signal is fed to the transistor base.
For additional details, have a look at http://tacashi.tripod.com/elctrncs/ssstc/ssstc.htm

Greetings from Niamey, Niger

Hi kas,

I suggest you develop an arduino software in order to explore different frequencies & duty cycle so you'll reach different resonances of your globe. At that moment, you'll realize it was worthwhile beyond just knowledge to have invested more than 200$ of equipment. To really make full exploratory, i suggest you also play with voltage control of your PSU because there is a sweet resonance plasma spot depending on a triplet <frequency, duty cycle, voltage>. Now, you'll also discover with professional isol-driver (IL610-MCP1403-IRF540) the resonance plasma impact of very sharp pulsing voltages impossible to obtain with a 4N25 and logig level fet  

Will experiment as suggested
Thanks for your comments

Finally... Arduino!!
The square wave generator is replaced by a diecimila board:



A minimal code to emulate the wave generator

Code:

// PWM with adjustable frequency and duty cycle  -  stripped version tested for Diecimila board
// Credit to westfw and selfonlypath

int on = 12;            // Parameters for frequency and duty cycle
int off = 48;           // 16.45 kHz   20% duty

void setup()
{
  pinMode(3, OUTPUT);
}

void loop()
{
  cli();
  while (1) {
    PORTD |= 0x8;        delayMicroseconds(on);           // pin 3  HIGH
    PORTD &= ~0x8;       delayMicroseconds(off);          // pin 3  LOW
  }
}

That's it,
the objective to replace 4 componants (2$) by 200$ worth of sophisticated equipment is fully reached  ;D  ;D  ;D
Knowledge is priceless...  

@ Selfonlypath
The scope is plugged between drain and V+ (HV transfo primary connections)
The MosFet drain is fed with 3.3V only

Hey kas, it seems your circuit is about pulsing on-off the plasma ball unit USB connector hence pulsing on-off the local oscillator inside plasma ball? If I'm right then I suggest you rather do the real stuff: remove inside plasma ball electronic then pulse directly the transformer with your driver

Hi Selfonlypath

Please refer to message #11:

First remove and save all components in the plasma ball base. The HV transformer has to be directly connected to the ball power

For convenience, the HV transformer is connected to USB plasma ball socket.

What do you think about the 14.7V peak to peak as per scope diagram ?? back EMF ??

Phase II (still without Arduino)  

Let's make our own electronic control device
First remove and save all components in the plasma ball base. The HV transformer has to be directly connected to the ball power socket.
The schematic is straightforward: Optocoupler for safety + Logic level N Mosfet
R1 limits current within the 4N25, to protect the internal diode
R2 acts as a pullup resistance

For more serious job (higher voltage/frequency), 4N25 should be replaced by a faster device, Mosfet should have higher Vds, driven by a Mosfet Driver to overcome gate capacitance.






For now, the Arduino is replaced by a square wave generator




Power supply delivers 3.3V, peak to peak output signal is 14.7V

Final (easy) step: the square wave generator will be replaced by an Arduino with adequate software

Stay tuned,
Happy New Year      

Plasma ball appeared on the market back in the 80'S at that time they were rather costly
They can now be had at no price (12$ + shipping here http://www.play-asia.com/paOS-13-71-134-49-fr-70-2xi4.html).
Now, let's sit down, plug it to an USB port and watch it... nice...nice... what next!!   :
For most of us, the answer is obvious: what's inside ???
Six screw later, here we are:
   




A PC board with an HV transformer, a transistor, a couple of condensators and resistances

The schematic:


The flyback transformer does trigger the base of the NPN D882P transistor; the system naturally oscillates at 20kHz



So what's next ???       Arduino of course!!!  
The idea is to remove all that junk, and drive the HV transformer from an Arduino's DO  

Stay tuned

Special thanks to Selfonlypath who convinced me to remove the dust sitting on my plasma ball since months.
Have a look at his youtube channel: http://www.youtube.com/user/selfonlypath.

Hi, I saw your smart arduino battery discharger today from randomly surfing and is very interested.  I have a few question hopefully you can help me out with it .  

The question I have is about the NPN variable resistor.

From what I understand the op-amp used as a comparator is used to limit the current draw from the battery? That if I set the Vref to 2V and initially Vp is greater than Vn in the opamp so comparator output goes to high 5V and the NPN is turned on and current flows through the shunt resistor.  And if current is too high then the feedback voltage Vn is now greater than Vp and comparator output goes Low and the BJT is turned off.  

I am just wondering if my observation is correct if not please shed some light on me

Hi aznweirdo

That's what it is  
according to Wikipedia:
When the non-inverting input (V+) is at a higher voltage than the inverting input (V-), the high gain of the op-amp causes it to output the most positive voltage it can. When the non-inverting input (V+) drops below the inverting input (V-), the op-amp outputs the most negative voltage it can. The OpAmp will output 0 or Vs (maxi) according to Vn-Vp sign.

Hi bitcurrent

Heat is actually shared among the two components (transistor, shunt).
You can use a 5W resistor, not less.
Heat will change resistor value and decrease accuracy
Another option is to choose a 0.1 R shunt, 1W should be OK
Don't forget to modify the code

Hi bitcurrent

You are right, the green big thingy is R2; this is a 0.47R 8W shunt resistor (SETA RB60)
Only one OpAmp is required for this project.
LM324 is a Quad OpAmp, LM358 is a dual OpAmp, both are inexpensive and OK for the job.
I finally switched to LM358 (8 pins) to save room on the PCB

The top side looks nice

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1266140108


The other side is... a bit more cluttered



Adafruit shield is V.5 as per http://www.adafruit.com/index.php?main_page=product_info&cPath=17_21&products_id=51


My advices:
First build your prototype on a breadboard http://www.adafruit.com/index.php?main_page=product_info&cPath=17&products_id=64&zenid=f74428807bfbe75ac921a42ac9b73ff6
Install only basic parts, ignore relay, buzzer and voltage divider
You don't need the heatsink if you only want to test AA or AAA batteries
Make sure everything is OK before any soldering
Develop a simple software that displays Volts and Amps on your computer.
It will be easy to add features once you have the basic design right

Oh... I finally built vesion 1 circuit, please ignore V2
Good luck,this is a very educational project
yves

P*r*ll*x

Whats this ? and why the necessity to cloak it ?
Are you using this in the picture . What is its relevence?

Private joke  
Some of us started learning microcontrollers with the Basic Stamp from Parallax: http://www.parallax.com/tabid/295/Default.aspx

Easy language, tons of documentation,
allthough technically limited, Basic Stamp is, in my opinion, the best option for absolute beginers (Julien...  : )

Now, the stand alone version with integrated LCD



This a serial display, back from my P*r*ll*x time  

The additional code

Code:

#define     LCDdisplay       1           // LCD display

In Setup()

Code:

#if defined LCDdisplay
  pinMode(TXPin, OUTPUT);              //------LCD setup-------//
  digitalWrite(TXPin,HIGH);  
  LCD.begin(9600);                     //9600 baud is chip comm speed
  LCD.print(22, BYTE);                 // cursor off, no blink
  LCD.print(12, BYTE);                 // clear screen
  delay(5);                            //----------------------
#endif

in display()

Code:

#if defined LCDdisplay
  LCD.print(12, BYTE);                         // **LCD**  clear screen
  delay(5);                                    
  LCD.print(L1, BYTE);
  if((loopCount/(60000/LOOP))<100)             LCD.print("0");
  if((loopCount/(60000/LOOP))<10)              LCD.print("0");              
                                               LCD.print((loopCount-1)/(60000/LOOP));
  LCD.print(L1+3, BYTE);                       LCD.print(":");
  LCD.print(L1+4, BYTE);
  if(((loopCount%(60000/LOOP))*LOOP/1000)<10)  LCD.print("0");              
                                               LCD.print((loopCount%(60000/LOOP))*LOOP/1000);
  LCD.print(L1+8, BYTE);                       LCD.print("mAh");
  LCD.print(L1+12, BYTE);                      LCD.print((int)mAmpH);
  LCD.print(L2, BYTE);                         LCD.print("mV");
  LCD.print(L2+3, BYTE);                       LCD.print((int)mVolt);
  LCD.print(L2+9, BYTE);                       LCD.print("mA");
  LCD.print(L2+12, BYTE);                      LCD.print((int)mAmp);
#endif

That's all folks, hope you enjoyed reading

@+
Yves

Hi Alvaro

What exactly are you plotting there ? battery voltage vs. time ?

Yes, Battery voltage (mV) versus time; I am sure you recognized the typical S shape.

I wonder if you can overlay also current (or voltage across sense resistor)

Data,including time, appear in the list box at the bottom of the diagram.
Current is kept at a constant value and needs no trending.

For this test: I=700mA, mAh integration ended up at 658 mAh, total discharge time: 56' 20"

I am preparing the LCD stand alone version, I hope to be ready this week end.

Yves

This chart reflects the discharge process (@1C) of a 1.2V AA battery:


The diagram is obtained using Stamp Plot light from Selmaware.
This freeware can be obtained here: www.parallax.com/tabid/441/Default.aspx  

Additional code:

Code:

#define     CHART             1             // Trend mode

In setup():

Code:

#if defined CHART
  delay(200);                                                       //------- Stamplot ---------------
  Serial.print("!TITL Battery tester");  Serial.print(13, BYTE);    // Set window title
  Serial.print(MESSAGE);                 Serial.print(13, BYTE);    // Set Status message
  Serial.println("!PNTS 6000");          Serial.print(13, BYTE);    // Set number of data points to collect
  Serial.println("!SPAN 500, 1500");     Serial.print(13, BYTE);    // Set maxi & mini range
  Serial.println("!AMUL 1");             Serial.print(13, BYTE);    // Set the value to multiply da
  Serial.println("!CLRM");               Serial.print(13, BYTE);    // Clear the message list
  Serial.println("!CLMM");               Serial.print(13, BYTE);    // Clear the MIN/MAX values
  Serial.println("!RSET");               Serial.print(13, BYTE);    // Reset the plot and all data
  Serial.println("!TMAX 3600");          Serial.print(13, BYTE);    // seconds maxi on x axis
#endif

in display():

Code:

#if defined CHART                                                 //StampPlot data for trending
    Serial.print((int)mVolt);            Serial.print(13, BYTE);
#endif