Arduino Controls 30,000 Volts

10 09 2011

All photos.

Today I made arduino control 30,000 volts.

My arduino has 3 channels of analog output 0 to 5 volt.

For testing I used this sin wave generator sketch:

 

 

int pwmPin = 9; // output pin supporting PWM

void setup(){

pinMode(pwmPin, OUTPUT); // sets the pin as output

}

void loop(){

float something = millis() / 1000.0;

int value = 127.5 + 127.5 * sin( something * 2.0 * PI );

analogWrite(pwmPin,value);

}

 

This generates a lazy 2 Hz sin wave.

But the output is not really analog, it’s pulse width modulation(PWM):

This tutorial shows how to smooth out  PWM using a low pass filter. My low pass filter used 6kΩ resistor and 4.7 µF @ 45V capacitor.

Here we have the raw PWM output superimposed with the filtered output:

Looks good!

Now we just add the voltage doubling op-amp circuit I made previously, and BOOM:

This shows the source signal and the voltage doubled signal.

Sweet! Now we can control the 30,000 volt glassman power supply.

Here the arduino is sending a slow sin wave to the glassman’s voltage control:

From 2011-09-10

The Glassman’s slew rate is really slow without a load.

Here is the setup:

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2.36 KiloAmps

6 09 2011

All photos.

Today I tested the newly rewound polywell coils and thicker leads. Best shot was 2.36 kA.

Now we are in the right neighborhood.





Terrifying Power

4 09 2011

All photos.

Tonight I really experienced the power of the coil power supply. Whoa.

I’ve been working to increase the coil current from ~1.2kA to ~2.5kA.

Previously I discovered the coil discharge path had more DC resistance than expected.

I rewound the Polywell coils with 16 gauge wire (previously 18 gauge).

The 16 gauge DC resistance is 144 mΩ compared to 227 mΩ for 18 gauge wire.

I beefed up other wires on the coil discharge path (4 gauge):

Lets test the wiring with the dummy coil:

I took the power supply up to 100V… a small test charge…

When I fired, the noise from the coil made me flinch. It was never that loud before.

Lets turn up the power!

300V for second test.

When I fired the coil there was lightning! HOLY CRAP.  Look what happened:

The coil fucking wrapped itself around the transformer (electromagnetic forming). Then it discharged to ground:

So I haven’t measured it yet, but I think we are getting more current to the coils.





My First OP-AMP Circuit

3 09 2011

All photos.

My Glassman high voltage power supply can be controlled with a 0-10VDC signal.

But most computer interfaces (like the arduino ) output 0-5VDC.

So today I built my first OP-AMP circuit to double a DC voltage:

I found a LM358M operation amplifier laying around.

Now I have a 2X voltage doubler! Sweet:

 





Circuit Modeling with SPICE

2 09 2011

Last week Raymond Rogers made a SPICE model of my coil circuit. Extremely helpful and awesome, thanks Ray!

SPICE is a general-purpose open source analog electronic circuit simulator.

I’ve been trying to get started with SPICE for a while now, but the steep learning curve prevented much progress. So to have a working example of a circuit I’m familiar with is so very useful.

Now we can run virtual experiment on the coil circuit and see how much current we get. Pretty damn cool!

Here are some example input values and resulting current graph:

Capacitance: 15 mF, 450V

Coil resistance: 180 mΩ

Coil inductance:  0.1mH

 

 

 

 

 

In this diagram the vertical axis is the voltage of a 1mΩ ammeter resistor, so 1V = 1KA.

I encourage anyone who knows splice to run this code, make changes and share results.

Also a shout out to jstults for his python script for inductance modeling.

THIS IS OPEN SOURCE SCIENCE.








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