I purchased two “Giant Super Sensitive MC6” GM tubes from Electronic Goldmine (Item Number : G18717, Unit Price: $89.95). These are Russian-made new-old-stock model MC6. They are 10.25″ long x 0.9″ diameter. I compared the sensitivity of these tubes to the other GM tubes that I use with my CDV700 Pro Geiger Counter. Continue reading
Image Credit: Tom Van Baak, Leapsecond.com
I was going through my e-mails for some information on atomic frequency standards, when I came across an e-mail that I had sent to Tom Van Baak in 2007 congratulating him for his family-friendly time dilation experiment. If you are not familiar with his work, I heartily recommend that you explore his precision-time-keeping webpage at LeapSecond.com. Continue reading
The book’s Figures 70 and 71 show our d.i.y. version of a popular apparatus to measure alpha particle scattering. The figure above shows additional views to help you build your own. The apparatus allows you to demonstrate alpha particle scattering discovered by Ernest Rutherford in 1908. Fundamental to the discovery of the atom’s structure, the experiment demonstrates that the charge of the atomic nucleus is concentrated at the center of the atom. Continue reading
Scionix in The Netherlands has taken advantage of the recent development of miniature mesh-type dynode photomultiplier tubes to construct small-diameter scintillation probes. Scionix’s miniature probes incorporate one of those PMTs, a NaI(Tl) scintillation crystal, and a built-in dynode voltage divider. Connection to the probe is made through a miniature high-voltage locking coaxial connector. Finding a mating connector is the main problem faced by enthusiasts who find these probes in the surplus market. Continue reading
Many surplus scintillation probes have a single connector through which the PMT is fed with high voltage and the anode signal is output. However, this may require an external “Bias-T” (a high voltage / signal splitter) to connect the probe to a high-voltage power supply that is separate from the PMT amplifier/processor. Continue reading
Figure 34 in the book shows the schematic diagram for our photomultiplier tube (PMT) signal processing circuit has an analog output that is suitable for use with a sound-card-based multichannel pulse-height analyzer (MCA). However, if you already have a commercial scintillation processor that you would like to use with PRA, then you will somehow need to extend the typically narrow output pulses (e.g. 1 to 10 microseconds) so that they can be acquired through the sound card. Continue reading
Last week I posted detailed construction information for my rubidium atomic clock frequency reference. Besides that unit, I also built a GPS-disciplined 10 MHz oscillator to serve as a secondary frequency reference, as well as a source of GPS NMEA data for my ham shack instruments that can use precise location and real-time-clock data (e.g. for satellite tracking). Continue reading
Transformers made for powering large neon signs are inexpensive and very reliable. Most commonly, the secondary is center-tapped, which prevents the use of its full peak-to-peak output in applications where one of the terminals needs to be grounded.
In the power supply described in this post, I took out the high-voltage transformer out of its metallic enclosure to isolate the center tap from ground. This requires very careful application of a thick insulated layer to the transformer. I used a full can of Shellac to patiently coat and re-coat the transformer. Continue reading
Efratom Model M-100 Rubidium Frequency Standard (RFS) oscillators are widely available in the surplus market. Units on eBay commonly sell in the $150 to $200 range. Despite their low surplus price, they were originally very expensive components, with superb performance. The M100 was designed to be used by the military as a master oscillator in high-performance communication systems, frequency standard equipment, advanced navigation equipment, and all other systems which require extremely precise frequencies and time intervals.
With the proper input power provided and suitable cooling provisions, you can turn a surplus M-100 into a free-standing 10 MHz +/-5×10-11 (+/-5 x 10 ^-11 in case that your web browser doesn’t display the superscript font) frequency standard for frequency counters, as well as a precise calibration source. I use mine to keep precise track of frequency when working on Earth-Moon-Earth (EME) communications, where even tiny errors in tuning can make the difference between success and failure to receive weak echoes. Continue reading
Experimental chemistry is not our forte, so we prefer to use professionally-manufactured quantum dots for the Schrödinger’s Wave Equation experiments we discuss in the book‘s Chapter 7. However, if you are interested in synthesizing your own quantum-dot nanoparticle suspensions, we recommend that you take a look at the detailed instructions prepared by Professor George Lisensky at Beloit College for the Preparation of Cadmium Selenide Quantum Dot Nanoparticles (Local printer-friendly copy at: CdSe_Quantum_Dot_Synthesis). Continue reading
Our two prior posts show how to build very high voltage power supplies using flybacks from old color TVs. The advantage of the method we use is that any flyback can be driven, regardless of how its primary is wired. This is because we wind our own primary using litz wire. Continue reading
We use the flyback-driver circuit shown in our d.i.y. 250 kV DC power supply in many other of our setups, so we built a stand-alone universal resonant transformer driver. Continue reading
High voltage DC power supplies are used by science enthusiasts for powering electron tubes and x-ray tubes, charging high-voltage capacitors, powering electrostatic “levitators”, etc. Many of these power supplies use a flyback transformer to produce high voltage at high frequency (AC), followed by a “Cockroft-Walton Multiplier” to rectify and dramatically increase the voltage.
The Cockroft-Walton multiplier uses a cascaded series of diodes and capacitors to generate a high voltage DC potential from an AC input through a circuit topology that uses diodes to charge capacitors in parallel and discharge them in series. The output polarity of the Cockroft-Walton multiplier depends on the way in which its diodes are oriented, so the output polarity (referenced to ground) of a high-voltage DC power supply is usually set during the design.
However, since some of our physics experiments require one or the other polarity, we build our Cockroft-Walton multipliers with an extra capacitor so that we can make our HV power supplies output either positive or negative high voltage referenced to ground. Continue reading
Image Credit: Daniel Vasconcellos
From: http://www.edn.com/article/471834-Something_from_nothing.php
I just posted at www.prutchi.com the construction of a simple, but very useful laser power meter. I used it to tune my 18 W CO2 laser, but the concept is applicable to any other high-power CW laser. Click here for a direct link to the blog post.
