Cutting-edge diy projects

Prutchi.com

Cutting-edge diy projects

Welcome to Prutchi.com!

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I STAND WITH ISRAEL

Welcome to my site, a blog dedicated to the cutting-edge do-it-yourself projects that I develop at home.  I like to make what I’ve learned available to others, so many of my professional and hobby projects are detailed in my books.

I am the co-author of “Exploring Quantum Physics through Hands-On Projects,” which will help you understand Quantum Physics through hands-on experiments that you can conduct at school or at home!

I am also the author of the book “Design and Development of Medical Electronic Devices,” which will let you master the building blocks of medical devices. I have thirty years of experience in the design of Medical Electronic Instrumentation, most of it developing active implantable medical devices. For my implantable devices site, please go to implantable-device.com.

My other books are “Exploring Ultraviolet Photography: Bee Vision, Forensic Imaging, and Other Near-Ultraviolet Adventures with Your DSLR” and “High-Power Near-Infrared Light Treatments for Depression, Dementia, and Other Brain Disorders.” All of my books are available on Amazon (#CommissionsEarned).

I discuss my other projects on this site. There is plenty of information, so take your time exploring.  Please navigate through the permanent pages, as well as through the many blog post categories listed in the sidebar to the right.

I hope that you enjoy reading my blog.

David Prutchi, Ph.D.

N2QG

#CommissionsEarned. As an Amazon Associate, I earn from qualifying purchases.

Take an unequivocal stand for basic human decency against Hamas!

Posted on by Posted in Administrative
I STAND WITH ISRAEL

I STAND WITH ISRAEL

Dear Friends and Colleagues,

On October 7, 2023, Hamas perpetrated horrific acts of pure evil against innocent civilians in the south of Israel. Hamas continues to launch rockets against population centers with the sole purpose of causing terror, destruction, and indiscriminate death. These crimes cannot be justified under any circumstances.

Now, a week after the terrorist attack, over seven million of my brothers and sisters in Israel, and millions of Jews around the world live in anguish about the welfare of the hostages taken by Hamas, and concerned about the safety of those in our families who have mobilized to defend our existence.

I do not ask you to take a political stance in the Israeli-Palestinian conflict. In fact, I believe that the Palestinian People are victims of Iran and its puppet Hamas’ complete disregard for human life. Instead, I ask you to take an unequivocal stand for basic human decency against the senseless and barbaric acts of terrorism perpetrated by Hamas.

Silence is complicity!

A Custom Base for using the EMI/Thorn 9816B Photomultiplier Tube with the Products for Research Model TE-182 Thermoelectrically-Cooled PMT Housing for Ultra-Low Light Level Experiments

Posted on by Posted in David, Quantum Physics

For a detailed writeup in pdf format please CLICK HERE

I’ve been planning some experiments with single-photon and ultra-low light levels. For these experiments I want the collection area to be large and for the detector to have very broad spectral response, so my preference is to use a photomultiplier tube (PMT) instead of a “silicon photomultiplier” avalanche single-photon detector.

I found a brand new EMI 9816B PMT on eBay® which meets my requirements. The 9816B is a 51 mm (2”) diameter end-window photomultiplier, with an S20 infrared-sensitive photocathode, and 14 BeCu dynodes of linear focused design. This tube features a very high gain of 25×106 A/lm under nominal conditions (2,200V) with a quantum efficiency of 21% at the peak response wavelength.

Integration time, and ultimately resolution and sensitivity for detecting single-photons or ultra-weak light levels are dependent on the noise floor (dark counts) which is a function of temperature. Cooling the PMT dramatically reduces its dark current and counts.

I bought a surplus thermoelectrically-cooled housing by Products for Research (Model TE-182) which is made for 2” end-window PMTs. I could not find a surplus base for the EMI 9816B 14-dynode PMT, so I decided to buy a surplus base for a different tube and modify it for the 9816B.

Products for Research TE-182 Thermoelectrically-Cooled Housing for 2″ PMTs

Clearing the inside of the base was a very messy affair. This is because the dynode voltage divider chain is partially potted in silicone, and the rest of the base is filled with expanding thermal-isolation foam. Part of the base is made of plastic, so the use of harsh chemical solvents or heat to remove the silicone rubber and expanding foam were not possible. I thus had to use a scalpel and dental picks to remove all this insulation and be able to disassemble the tube socket.

I built a new divider on a piece of phenolic breadboard . The base is wired for high voltage (-2,300V) applied to the cathode (through a 33k? resistor). The dynode_1-to-dynode_14 divider is built with 330k? resistors. As suggested by EMI, the cathode-to-focus (and dynode_1) is set at a fixed 300V difference using two 150V Zener diodes in series.

Results from a characterization run are shown in the following table. The room-temperature dark current agrees with the specified value. A very dramatic drop in dark current and dark count rate can be observed when the PMT is cooled.

For a detailed writeup in pdf format please CLICK HERE

Febetron/Fexitron High-Voltage 2-Stage Marx Generator Module

Posted on by Posted in David, High Voltage

I have kept on making space in my lab for new projects, and came across 3 new-old-stock Marx generator modules that were made for the Fexitron and Febetron flash X-ray sources and electron accelerators.  The Fexitron and Febetron devices were made in the 1970s by the Field Emission Corporation, a division of HP, which is now L-3 Pulse Sciences.

Each module contains two complete 30 kV Marx stages.  In the Febetron/Fexitron pulsers, modules were stacked to form Marx generators of up to 2.3MV output. The spark gap distance is adjustable. These modules are designed for use under 20-70 psi air or nitrogen.

My intention was to build a 180 kV fast Marx with these, so I had reverse-engineered the schematic for these modules.  I’m putting it here in case that someone is interested.

The following are interesting links related to Fexitron/Febetron units: