Just got this Tektronix P6015 high voltage probe. It goes up to 40 kV!
Well actually it only goes to 27 kV without the fluorocarbon 114 dielectric.
It’s huge! Shown next to a normal probe:
Just in time for the next run.
This is the same probe used in the Sydney experiment.
Reader jsults turned my on to g3data… it’s a little open source program that helps extract data from graphs.
It looks like this in action:
I tried it with my oscilloscope photographs and it worked OK. But it does not compensate for trapezoidal distortions.
If my camera were perfectly lined up with the oscilloscope g3data would work great.
This got me to thinking… maybe I could build a camera holder for the oscilloscope?
So I did.
I designed this mount using sketchup and had it printed at shapeways. It came in the mail today.
Works like a charm. Now all my oscilloscope photos will be perfectly centered and flat:
You can download at thingaverse or purchase at shapeways.
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:
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| From 2011-09-10 |
The Glassman’s slew rate is really slow without a load.
Here is the setup:
Here is a quick tutorial on how to read an oscilloscope.
Voltage increases as you go up the screen.
Time passes from left to right.
The three numbers circled below are the keys.
In this example:
1V means the distance between each gridline bottom to top represents 1 volt.
500µs means the distance between each gridline left to right represents 500 microseconds.
2.160V is the voltage between two lines I manually adjust. This is called a cursor.
The small cross circled on the lower left indicates zero volts.
Those are the basics of reading a ‘scope.
I recently purchased a used Tektronix 2445 oscilloscope. It’s a 4 channel 150 MHz analog scope.
I also purchased a Tektronix 2430 digital scope which is en route. The digital scope has the key advantage that it can capture and display a single frame from a trigger. The digital scope will show readings from the Langmuir probe in the Sydney experiment.
It has taken me a few days of reading the manual and playing around with the scope to get a grasp. But I’m getting the hang of it, and wow… it’s a new way to explore the world!
My first discovery is that one of my bench DC power supplies is rather noisy:
The other bench power supply looks much cleaner:
But neither DC power supply is as clean as the perfectly flat signal you get from a battery.
I also used my iphone to display some sine waves:
Back in the lab today after some travel out west.
Previously I designed a bellows holder to keep the high voltage feedthrough from moving.
I received the part and installed it successfully today:
A real win using 3D metal printing.
I just scored this sweet vintage military fast neutron counter for $370!
IM-169/PDR-47C
RADIACMETER
Serial A 21
Unit of Radiac Set AN/PDR-47C
Manufactured for NAVY DEPARTMENT-BUREAU OF SHIPS
By contractor
NUCLEAR CORP OF AMERICA
Denville NJ
DT-240/PDR-47C
Probe, Radiac
Where would I get this thing calibrated?
Most of the parts for the Langmuir probe are here.
The probe will connect via the rear 8″ conflat:
Unfortunately, this 8″ conflat holds the chamber up! So I whipped up an 80/20 solution:
You can see the chamber is supported on either side by 80/20:
Stuart has the long socket wrench we’ll need:
We have ceramic tubes left over from the fusor grid. However, they don’t quit fit together. I’ll have to file the smaller one with a diamond file. Easy.
An open question:
Finally… I still need to purchase the super thin tungsten wire that will form the tip of the Langmuir probe. Anyone have a foot or so of thin tungsten wire?
I’ve been gathering the parts necessary for the next round of experimentation.
High voltage feedthrough for the Langmuir probe:
8″ to 2.75″ reducer for the langmuir probe:
Trigatron to discharge huge capacitor. Everybody say that out loud: TRIGATRON.
It’s the coolest word ever invented. Spec Doc.
20V 3A benchtop power supply by Sorensen. This will power the heater on the superconductor’s persistent switch.
Also for the superconducting coils I got this benchtop dewar for the liquid nitrogen:
More 80/20:
And finally a 160-in-1 electronics kit. So much better than the one I had as a kid. My 12 year old self is SO JEALOUS!
I recently acquired a remarkable little piece of technology called eye-fi. Its an SD memory card for your digital camera with built in WIFI. As soon as I take a picture it is uploaded to Picassa and my computer. It’s amazing.
Photography is the most important part of this blog, but until now… the most cumbersome. It was a 10 step process to get a photo from my camera to the blog. Now I am publishing a photo stream just by taking the photos. So easy.
The upshot is I will be publishing about 100 photos every day I’m in the lab… you will literally see them before I do.
So without further ado, here is the new photo stream. And here is a tour of the lab in photos from today. Some highlights:
Picked up a wireless USB hub:
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