Oscilloscope

25 01 2011

All photos.

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:





Cold Fusion

17 01 2011

Italian researchers Focardi and Rossi claim to have made a break even cold fusion reactor. Huge news if it is true.

Seems still in the press release phase, but I’ll be keeping an eye on this story.

More detail in the patent application and technical paper.

Worth mentioning that the device is dead simple. It would be relatively easy to replicate the experiment.

For background see article on cold fusion.

UPDATE:

Physorg is covering the story with due skepticism. This paragraph is most telling to me:

Rossi and Focardi have applied for a patent that has been partially rejected in a preliminary report. According to the report, “As the invention seems, at least at first, to offend against the generally accepted laws of physics and established theories, the disclosure should be detailed enough to prove to a skilled person conversant with mainstream science and technology that the invention is indeed feasible. … In the present case, the invention does not provide experimental evidence (nor any firm theoretical basis) which would enable the skilled person to assess the viability of the invention.

 





Coil Power

5 01 2011

All Photos.

I have finished the coil power supply. All bolted down and wired up.

Here is an oscilloscope of the SCR’s trigger circuit pulse:

Notice the fast rise time.





Radiation Survey & Pump Prep

3 01 2011

All photos.

I’m preparing to send the broken pumping station back to Pfeiffer Vacuum. Did you know “pfeiffer” is German for “piper; player of the bagpipes”!

Pfeiffer requires a radiation survey of the pump. In our case we are looking for radiation from neutron activation.

I used the sparkfun USB geiger counter for this survey:

I started with a 10 minute background reading 9.7 Meters from the pump.  91 clicks or 0.1516 clicks per second:

The UBS geiger counter produces a digit for each click. You can actually hear the geiger counter make a sizzling sound with each click… it’s wild.

Next I did a reading at the exterior of the pump. 88 clicks in 10 minutes. 0.146 clicks per second.

Again with the geiger counter inside the pump. 83 clicks in 10 minutes. 0.138 clicks per second.

I’d say the pumping station is clean.

I put the pumping station back in its crate:

As a side note, this USB geiger counter produces high quality random numbers:

UPDATE:

I asked P. Andrew Karam, Ph.D (radiological specialist) to comment on my survey approach. He says:

Looks good, Mark – the biggest thing you are looking for is a significant number of counts above background.  You really don’t need to convert everything to CPS – the big thing is to make sure that the readings are all made using the same instrument and for the same amount of time.
In counting statistics we normally use a few concepts – LLD (lower level of detection) and Lc (Decision level).  These are the levels at which we feel we can definitively say that there is contamination (or activation) present.  The LLD is usually about 2 standard deviations higher than the average count rate – using Poisson statistics, one standard deviation is approximately equal to the square root of the total number of counts. So with a background count of 91 in 10 minutes one standard deviation is about 9.5 total counts.  That means that anything less than about 19 counts above background (so less than about 110 counts total) is within the expected statistical variability of your instrument.  The Lc is a somewhat more difficult calculation in that it depends on your survey speed as well as the size of the probe, counting time, and background counts.  Having said all that, the fact that your highest reading was background and everything was within 1 standard deviation of background tells us that you don’t have any neutron activation that is detectable with a GM.
One question – 90 counts in 10 minutes is not very much for a GM – I am used to seeing about 50 cpm (or almost 1 cps) from my GM.  I suspect that the reason for the low count rate is the relatively small size of the GM tube itself – the counts you get are a function of the cross-sectional area of the tube.  Not disqualifying – just a comment!
The only other question that might come up is whether or not your GM is calibrated – if Pfeiffer were to find elevated rad levels (which I doubt they will find, by the way) they might ask for calibration documents on your meter.








Follow

Get every new post delivered to your Inbox.

Join 669 other followers

%d bloggers like this: