Cutting-edge diy projects
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). I just posted on www.diyPhysics.com details about this 10 MHz GPS-disciplined standard. Continue reading
I just posted on www.diyPhysics.com about my 10 MHz rubidium standard based on a surplus Efratom M-100. It is a free-standing 10 MHz +/-5×10-11 frequency standard for frequency counters, as well as a precise calibration source. I use it 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
SharkVision – A Sensing Suit for the Blind
Hannah Prutchi, 8th Grade, Science, VMS, October 2011
Blind people often use canes to avoid obstacles when walking. But, these are intrusive, can only detect obstacles where they are pointed, and could be dangerous to other people. I devised the “SharkVision Suit” to help blind people move around their environment more easily.
I developed this idea from the concept that sharks find their prey by sensing disturbances in an electrical field they form around their bodies. This suit simulates the shark’s ability to sense objects around its body, giving a blind person a new type of sense. Continue reading
I just posted at www.diyPhysics.com detailed instructions on the construction of a 250 kV DC high-voltage power supply. Although my hack for switching the polarity (referenced to ground) is simple, I am very surprised that I’ve never seen it elsewhere!
In my dayjob as an implantable-device engineer, I often need to prototype small parts. So, after the successful modification of my home X2 mini mill to CNC, I decided to do the same to the Sherline precision micro mill that I have at work. Continue reading
From Saturday Morning B
In my prior post I told about components in my CO2 laser’s RF power supply becoming unsoldered when they overheated. After the repair, I needed some way of retuning the RF output stage for maximum laser output. This motivated me to build the power sensor shown in the picture above. Continue reading
I was thinking about buying a laser engraver/cutter for home, but after retrofitting for CNC the Micro-Mark mini mill that my wife gave me for my birthday, I figured that I could simply add a CO2 laser to the X2 mini mill.
Before describing the mod, I figured you would want to see some results. Here is a YouTube video of my X2 mini-mill laser engraver in action: Continue reading
Military-surplus scintillation probes meant for the detection of plutonium contamination are widely available in the surplus market. The DT590A/PDR-56F “Plutonium-239 Contamination X-Ray Probe” was used with the PDR-56 Radiac Set (radiation detection and measurement instrument), that has been obsoleted by the US Air Force.
The probe is designed specifically for detecting the 14 to 21 keV gamma lines emitted by Plutonium-239 along with its main alpha-particle emissions. For this reason, despite its availability in the surplus market, this probe has not found wide acceptance by science enthusiasts interested in radiation counters.
I just posted to www.diyPhysics.com detailed instructions for the construction of my home-built PDR-56-like radiac set capable of driving a surplus DT590A/PDR-56F “Plutonium-239 Contamination X-Ray Probe.” In addition, I also give instructions on how to open the single-channel analyzer window to convert the instrument into a very sensitive, general-purpose gamma radiation counter. Continue reading
Some time ago I was developing a medical instrument which required histogramming, which got me in the mood to retake my own PIC MCA project(http://home.comcast.net/~prutchi/index_files/scint.htm ). I used the variable RAM in the microcontroller (16F877), so I limited the number of channels to 95 and let the histogram run until some channel reaches 240 counts (the highest 8-bit number that yields an integer when divided by 8). The firmware then displays the spectrum as a bar with a maximum height of 30 pixels for each one of the 95 channels.
Click here for complete how-to construction instructions in pdf format.
Click here for a pdf of the schematic diagram for the front-end of the MCA
