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361  Forum 2005-2010 (read only) / Exhibition / Re: A simple security system on: October 22, 2010, 06:18:05 am
Nice job swseansw

My advice: find a nice box to package your project  smiley-wink
362  Forum 2005-2010 (read only) / Exhibition / Re: Very Large 7Seg display - Flourescent tubes on: October 27, 2010, 11:22:44 am
What shall I say...  giant project !!   smiley-wink
363  Forum 2005-2010 (read only) / Exhibition / Re: silly meccano classic bot on: October 16, 2010, 01:01:15 pm
Nice job aventgps

Would you mind posting your source code
I am especially intrerested by the IR sensor servo-mounted control

I do remember your CNC machine  smiley-wink
364  Forum 2005-2010 (read only) / Exhibition / Re: Automatic Toilet Flusher on: September 26, 2010, 12:31:53 am
Probably needs some refining; but you did it  smiley-wink

The place of Aduino is definitly ... anywhere  ;D ;D ;D
365  Forum 2005-2010 (read only) / Exhibition / Re: Plasma Ball anatomy on: September 29, 2010, 07:36:07 am
Quote
what is the voltage that 3,5" made in china flyback (OY-12-2) generates as is when supplied with USB voltage?
I suspect that flyback voltage output should be around 5000/10000V
Selfonlypath, did you perform output voltage measurement ???
366  Forum 2005-2010 (read only) / Exhibition / Re: Plasma Ball anatomy on: July 16, 2010, 02:30:05 am
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"
367  Forum 2005-2010 (read only) / Exhibition / Re: Plasma Ball anatomy on: July 02, 2010, 10:51:54 am
I had a look at and
Nice job, seems this is a new step in your ZPE quest   :smiley

What is the point of replacing Mosfets by IGBT's in your new setup ??
368  Forum 2005-2010 (read only) / Exhibition / Re: Plasma Ball anatomy on: January 11, 2010, 02:16:04 pm
Quote
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
369  Forum 2005-2010 (read only) / Exhibition / Re: Plasma Ball anatomy on: January 04, 2010, 08:26:26 am
Quote
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
370  Forum 2005-2010 (read only) / Exhibition / Re: Plasma Ball anatomy on: January 02, 2010, 11:37:15 am
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...  smiley-wink

@ Selfonlypath
The scope is plugged between drain and V+ (HV transfo primary connections)
The MosFet drain is fed with 3.3V only
371  Forum 2005-2010 (read only) / Exhibition / Re: Plasma Ball anatomy on: January 02, 2010, 04:16:13 am
Quote
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:
Quote
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 ??
372  Forum 2005-2010 (read only) / Exhibition / Plasma Ball   Phase II on: December 31, 2009, 10:04:02 am
Phase II (still without Arduino)  smiley-wink

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  smiley-grin  smiley-grin  smiley-grin
373  Forum 2005-2010 (read only) / Exhibition / Plasma Ball anatomy on: December 25, 2009, 08:02:15 am


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!!   :smiley
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!!!   smiley-wink
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.


374  Forum 2005-2010 (read only) / Exhibition / Re: Smart battery discharger/tester on: September 24, 2010, 04:27:27 am
Quote
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  smiley
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.
375  Forum 2005-2010 (read only) / Exhibition / Re: Smart battery discharger/tester on: May 02, 2010, 10:11:33 am
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
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