Applied Science

I cut open a cathode ray tube (picture tube, or CRT) and explain the internal parts and their function.

Link to the instructables article (not written by me): http://www.instructables.com/id/How-to-make-air-muscles!/ Silicone tubing - McMaster 51135K281 Braided wire loom (polyester) - McMaster 9284K413 http://benkrasnow.blogspot.com/2011/02/how-to-build-air-muscle-and-use-it-in.html

Today, I finally produced an image with my DIY scanning electron microscope. I've spent the last few months working on this project, and am encouraged by today's success. There is still a lot of work left to do in making the image higher resolution, and eliminating sources of noise, however this image proves that all parts of the microscope are operating as designed. I will be showing this project at Maker Faire 2011 in San Mateo. Come see it for yourself in person! http://benkrasnow.blogspot.com/2011/03/diy-scanning-electron-microscope.html Search my blog for "microscope" for additional images and info: http://benkrasnow.blogspot.com/

Please visit my blog post to see the references and sources for this project: http://benkrasnow.blogspot.com/2011/03/diy-scanning-electron-microscope_26.html

Vote for me here: http://mytektronixscope.com/videos/ I am using my Tektronix 2246 analog oscilloscope to show the image generated by my DIY electron microscope. The 2246 is operating in X-Y mode, with the channels connected to a raster scan generator. The vertical scanning frequency is about 30Hz and the horizontal frequency is about 10KHz. The trace brightness (Z axis) is modulated with the secondary electron signal from the microscope.

Here's another project similar the the fiberoptic joystick that I built. It uses the same 62.5 micron telecom fiber to sense X/Y velocity as well as two buttons in a standard computer mouse. This mouse is designed to be used in environments were electrical signals cannot be tolerated.

I explain the detailed operation of the electron gun in my DIY scanning electron microscope project.

Here's a project that makes use of these electronic Braille characters: http://www.metec-ag.de/braille%20cell%20p16.html I built a bunch of transistor amplifiers and use two 74hc373 chips driven by the parallel port to control the state of both Braille characters. Excellent resource for PC parallel port control: http://www.beyondlogic.org/spp/parallel.htm

I describe how to design a simple transistor circuit that will allow microcontrollers or other small signal sources to control low-power actuators such as solenoid valves, motors, etc.

I built a simple working model of a 3D printer for demonstration at a school. My intention is to show the students how 3D printers work at their most basic level. The model provides a hands-on activity and can create alphabetic letters or other small souvenirs that the kids can take with them.

I am in the process of upgrading the lighting in my shop. It currently has a number of 4-lamp and 2-lamp T12 4-foot fluorescent fixtures. The best solution is to replace the ballast in each of these fixtures with high-efficiency electronic ballast ($15), and replace the lamps with T8 high-CRI bulbs. This will save energy, and greatly improve the quality of the light. LEDs and T5 fluorescent are MUCH more expensive to install, and their energy savings are not nearly enough to justify the cost. Remember that running a T8 with an electronic ballast will provide more light than it's nominal rating, which is for magnetic ballasts. T5 are always rated for electronic ballasts, so it is not a fair comparison. For new fixtures in my shop, the cheapest/best solution is to buy $10 "shop lights" and replace the ballast. The total fixture cost is $25, and efficiency is 96 lumens/watt for a total output of almost 6000 lumens. It can't be beat! Commercially-available T8 fixtures with electronic ballasts are more expensive, and the quality of the ballast is suspect.

I recently bought a Grizzly 4003G lathe, which has proven to be a very useful tool in my shop and a major upgrade from my previous lathe. The 4003G is a great value, and I would definitely recommend it for anyone looking for a 12x36 lathe for hobby or semi-pro work.

After getting back from Maker Faire (which is always a hugely enjoyable and inspiring event), I thought that my microscope might need some repairs. As it turned out, I only had to change the filament and tighten some screws that came loose during the trip back from the Faire. The microscope works just as well as it ever has -- I didn't even need to move my alignment magnets. I made this video to show everyone what using it is really like. Also, if you haven't been able to attend Maker Faire yet, it really is as amazing and epic as you have heard. The intelligent and inspiring people who make it happen are a large part of the motivation that I had to build and display this microscope. In turn, I hope my project inspires others to create things and share their ideas with everyone. There's no better way to have fun and celebrate accomplishment at the same time!

This is the first video of a short series in which I discuss the basics of electrical impedance from a practical standpoint. In this video, I show how a simple LED power supply circuit can be made more efficient by replacing a resistor with a capacitor. I describe the difference between resistance, reactance, and impedance.

This is the second video of a short series in which I discuss the basics of electrical impedance from a practical standpoint. In this video, I explain the importance of knowing the magnitude and angle of impedance, as well as how this affects the power factor of a given electrical circuit.

My first youtube videos were made with my camera's on-board stereo microphone. The camera is a Lumix GH1, and the mics are fairly good as far as prosumer video DSLR cameras go. One problem is that the camera's automatic gain control cannot be turned off, and having unexpected gain changes during an audio recording is not preferable. Another problem is that the audio preamplifiers in the camera are somewhat noisy, and lead to a lot of hiss (high noise floor) in the recording. Finally, it's impossible to get good sound when the microphone is positioned far away from the sound source when room tone and echoes are present. The solution to all of these problems is to make use of a lavalier or lapel microphone and use a low-noise dedicated recording device. I use a Zoom Handy H4 recorder. The H4's on-board mics are really nice, but it is still preferable to have a microphone very close to the subject's mouth to capture detailed, high-quality sound. I started using an Audio Technica ATR-3350, which is only $20 or $30 new, and the mic is OK, but has very little high-frequency response. This can be corrected with equalizer settings in post-production fairly well. I recently upgraded to a Sony ECM-55B, which sounds better, but I am not sure it was worth the expense. I was really expecting the mic to have a much higher output level than the ATR-3350, thus allowing me to turn down the gain on my recorder and have a much lower noise floor. As it happens, the mic requires even more gain than the ATR-3350. Overall, I am pretty satisfied with my sound recording setup -- the only addition I might make is a low-noise preamp to try boosting the lavalier mic signal while adding less noise than the H4 adds during the high pre-amp gain stage.

I bought six 2600F 2.5V ultracapacitors from Electronic Goldmine. They were on sale a couple weeks ago, and this was one of my rare impulse purchases. I am thinking of building a portable capacitive discharge welder, or perhaps conventional spot welder. What are your ideas?

One of my ongoing projects is to develop a low-cost thermal imaging camera. In this video, I take apart an Extech IR250 infrared thermometer with the intention of grabbing an analog or digital signal so that I can record temperature measurements while using a scanning or image processing device to select portions of the scene being examined. Unfortunately, it looks like the analog circuitry is completely sealed inside a custom IC that is hidden under a blob of potting material. I'll remove the IR sensor from the board and build my own analog amplification and digitization hardware. Common digital output IR thermometer sensor: http://www.melexis.com/Infrared-Thermometer-Sensors/Infrared-Thermometer-Sensors/MLX90614-615.aspx TPS334 sensor datasheet: http://www.datasheetcatalog.org/datasheet/perkinelmer/TPS334.pdf Analog Devices app note regarding thermopile sensors: http://www.analog.com/en/all-operational-amplifiers-op-amps/operational-amplifiers-op-amps/products/technical-articles/using_thermopile_sensor_in_ir_digital_thermometers/resources/fca.html Servo pan/tilt IR imaging scanner project: http://www.cheap-thermocam.tk/ Redshift thermal imaging: http://redshiftsystems.com/site

Here's a project that I built to feed my cat when I am away for short trips. It uses a commercial dry cereal dispenser, stepper motor that was hacked into an old HP Laserjet gearbox, ATMega8 AVR microcontroller, and standard mechanical AC lamp timer. http://benkrasnow.blogspot.com/2009/02/automatic-cat-feeder.html http://benkrasnow.blogspot.com/2009/08/improved-automatic-cat-feeder.html

Transcranial Magnetic Stimulation (TMS) is a technique to stimulate brain tissue directly through the skull. It works by sending a very high current pulse through a coil that is located on the subject's scalp. The fast-rising edge of the pulse induces a current in the brain tissue, causing neuron stimulation. This device uses a capacitor bank, high current SCR, trigger circuit, figure-8 (or butterfly) coil, and high voltage charging circuit. Link to the SCR datasheet: http://www.5scomponents.com/pdf/5STH_30J4501.pdf Some good technical information: http://www.abovesobelow.com/TMS/cTMS.pdf Wikipedia: http://en.wikipedia.org/wiki/Transcranial_magnetic_stimulation

I bought this bargain basement clamp-on current probe on eBay. It doesn't even seem to have a manufacturer (shamed out of existence?), but the model number is CP06. It's $70 shipped, and is probably worth it, especially if you plan to measure DC and 50/60Hz AC waveforms. It will not do high-frequency measurements. The DC accuracy seems good enough for many different applications where cutting into the test wire is not preferable. Note: Hold down the "zero" button for a couple seconds, then release.

I am testing the frequency response of the TPS334 IR sensor. My very crude tests agree with the datasheet, which means that the image scan time will be very long for high contrast images. Many low-cost microbolometer-based thermal imaging cameras have 80x80 sensors (6400 pixels). At a 10Hz pixel clock (-3dB sensitivity from datasheet), the frame scan time would be 640 seconds, or nearly 11 minutes. Yikes! At 100Hz, the sensor would only produce an output level of %10 of its DC capability, and still require just over a minute to scan the whole frame. Obviously, this will not be a "live video" system, but might still produce some interesting still image thermographs. I am working on other methods of sensing long-wave IR too. More later.

I ignited four pounds of thermite made with aluminum / iron (III) oxide in a flower pot. The thermite reaction quickly formed liquid iron which dripped down out of the pot, and into a ceramic pan. I put a beef kebab directly onto the liquid iron, which cooked the food in under a minute. It was delicious!

I achieved neuronal stimulation of my primary motor cortex by using a single 15-turn coil and 1700 volt charge on the capacitor bank of about 190uF. The exact position of the coil on my scalp makes a very big difference in how much stimulation is achieved in the motor cortex. I would have suspected the single coil would produce much more diffuse stimulation and positioning would not be so critical. I never got any decent neuronal stimulation with the butterfly coil.

The 5V fixed output on my Shenzhen Mastech HY3005D-3 power supply died the other day, and so I took the device apart to investigate. The 5V regulator board had a bad solder joint where the bridge rectifier attaches to the PCB. I used a soldering gun to reflow the joints, and all seems good.

I built this project a few years ago with a friend to help get him interested in mechanical design. Later, the project was adapted for display at a "tech and art" exhibition at San Jose City Hall. After 8 months, the painted steel impeller began to rust and discolor the water in the tube. I took the device back to my shop and replaced the original aluminum shaft with a stainless steel shaft, replaced the shaft seal, and changed the impeller to an all-plastic design. If I were designing the device again, I would opt for a spring-loaded PTFE (Teflon) shaft seal, which I have used with great success in other applications. Drill motor control: http://www.youtube.com/watch?v=7yEABsNyRfo Original video showing the WiFi-controlled watering can and vortex tube: http://www.youtube.com/watch?v=XKrlRJ-GJms

I am not sure of the chemistry involved, but I have found that acetone and isopropanol vapor will darken the ink in thermal printer paper. There is also a strange reversible blanking effect, where continued vapor application will cause the dye to temporarily become colorless. Do you know the chemistry involved?

I've been cutting glass plates and mirrors with my CNC milling machine machine for years. In this video, I describe a few tips and the general technique that I use. Clamping the glass plate to the table is the critical part of the process, and so I built a jig that allows the glass to be held laterally with shims, but does not require a high clamping force, which would crack the glass. Cutting parameters: .085" dia diamond burr 3000 RPM 1-3 inches per minute feed Cut depth .130" (full material thickness) Flood coolant with soluble oil cutting fluid http://benkrasnow.blogspot.com/2011/08/cnc-milling-glass-plates-and-mirrors.html http://benkrasnow.blogspot.com/2008/08/cnc-milling-glass-plates-and-mirrors.html

This is my first experience with FPGA programming, and so I made this video to show how easy it is to get started. Many of the tutorials on the web and the DE1 manual make the process seem more difficult than it actually is (as usual). http://benkrasnow.blogspot.com/2011/08/getting-started-with-altera-de1-fpga.html

This has been done many times, but is still fun and easy. This is the first time that I have tried it myself. The reaction produces Magnesium Oxide and Carbon 2 Mg(s) + CO2 yields 2 MgO(s) + C(s)

I built a pressure vessel from aluminum and acrylic, and filled it by placing pieces of dry ice inside. The dry ice melts under high pressure, and forms a liquid and gas phase. When the vessel is heated, the CO2 becomes supercritical -- meaning the liquid and gas phases merge together into a new phase that has properties of a gas, but the density of a liquid. Supercritical CO2 is a good solvent, and is used for decaffeinating coffee, dry cleaning clothes, and other situations where avoiding a hydrocarbon solvent is desirable for environmental or health reasons. If you have a suggestion for what I should do with the supercritical CO2, please leave a comment. CO2 can be liquefied in plastic bottle preforms: http://www.youtube.com/watch?v=8AN_XMcD3yI It may be important to open the container before all of the solid melts. When there is still some solid CO2 present, the pressure will be close to the triple point. Once the solid completely melts, the pressure will increase quickly to about 750 psi depending on the ambient temp. I really doubt those plastic containers could hold 750 psi. My first look at supercritical fluids: http://www.youtube.com/watch?v=yBRdBrnIlTQ Another youtuber interested in supercritical CO2: http://www.youtube.com/watch?v=GEr3NxsPTOA Added engineering recap and formulas: http://benkrasnow.blogspot.com/2011/09/close-look-at-supercritical-carbon.html

I will be adding a valve to the chamber so that I can release pressure in a more controlled way.

Most beer is carbonated with 100% CO2. Some beers, notably Guinness and some other porter/stouts, contain a mixture of nitrogen and CO2 in a ratio commonly 75/25 N2/CO2. The nitrogen is less soluble in water, and allows the beer to be served at a higher pressure without dissolving too much gas into the beer itself. The higher serving pressure churns up the beer as it exits the spout, and creates a creamy head that is the signature of a good Guinness pour. Some pubs use 75/25 gas to push normally carbonated beers out of the tap, but the beers themselves contain only CO2. In this video I wondered what would happen if I used argon instead of nitrogen. I started by using %100 argon since the solubility of Ar is between that of N2 and CO2. As it turns out, the Ar is not soluble enough to produce a decent head on the beer. Additionally, the complete lack of CO2 makes the beer taste sweet (like it's flat) since the CO2 is necessary to form carbonic acid in water, and this is an important flavor component of beer. Xenon has anesthetic properties at atmospheric pressure, while the other noble gasses can become anesthetic at higher pressures. Does anyone want to explore xenon beer, or have any experience with xenon used as an anesthetic?

I tried to extract caffeine from green coffee beans using supercritical CO2, but I had no success. The beans underwent a strange transformation, becoming white and rubbery after 6 hours at 80*C in supercritical CO2. I also used water and ethanol as a cosolvent, thinking that the caffeine would end up in solution in the water/ethanol mix after the CO2 became subcritical. Do you have any advice about how this process is supposed to work?

I left my supercritical CO2 chamber charged up with 750 psi liquid CO2 (not supercritical) for about a week. I then depressurized the chamber, and opened it. At first, the acrylic seemed fine with just minor surface crazing. After a few hours, I was surprised to find the acrylic had deformed in a major way and was full of CO2 bubbles. Weird!

I show how to weld aluminum cans together with a cheap import TIG welder. I am not a professional welder, so some of my advice may be unconventional or even wrong, but these methods work well for me. With a 3/32" electrode and large gas lens, I don't have to change the torch setup for nearly any kind of common welding. Let me know if you have any questions or would like me to make more welding videos. Some things that I have learned: Don't use pure tungsten electrodes. The new rare-earth blends work very well on nearly all metals. Sharpen the electrode to a very fine point for low-current welding, and sharpen it like a pencil for higher (eg over 100A) welding. Keep the electrode balance control electrode negative ("weld") and only shift toward electrode positive ("clean") when absolutely necessary. The welder's pulse feature turned out to be not as useful as I originally thought. It just seems to complicate things. It's definitely possible to make great welds without it. Use fat electrodes. Some people claim that using an electrode that is "too large" for the weld current will cause the arc to wander. Nope. Just grind it to a sharp point. Thin electrodes 1/16" and .040" overheat much too easily, and provide no apparent benefit. .040" electrodes are very frustrating. Use thin filler rod. It's much easier to feed thin rod quickly than feed fat rod slowly. As I mentioned in the video, it's easier to sneak a thin filler rod into the puddle while keeping the torch close to the surface.

This proves that proper technique is more important than brute strength if even I can rip a phone book in half. There are many tutorials, eg http://www.youtube.com/watch?v=gYTpTPOSbd0

http://www.techkits.com/kits/index.htm#sla7062 Stepper motors can be made to rotate more smoothly by providing simulated sine waves. The SLA7062 chip uses internal PWM to provide sinusoidal current waveforms to unipolar stepper motors. I have this working fairly well, but the PWM frequency is acoustically apparent and annoying.

This is a project that I built a few years ago when I learned about liquid lenses. They are quite useful for optical paths with small diameters. http://www.supertex.com/pdf/datasheets/HV892.pdf http://varioptic.com/en/products.html http://benkrasnow.blogspot.com/2009/07/experimenting-with-liquid-lens.html

I built a pressure chamber from 2" pipe fittings and 1/8" brass valves to contain supercritical CO2 for drying applications. One project is to try aerogel production which generally requires that solvent be removed via supercritical drying. Normal evaporation would deform the aerogel structure as the surface tension of the solvent pulls the gel's structure tighter together and makes it dense. Since supercritical fluids have gaseous properties, they can diffuse out through the gel without affecting the structure the way that a liquid would.

I tried to build a cloud chamber with supercritical CO2, thinking that ionizing radiation (alpha particles) would cause localized condensation of the CO2 at the point where the fluid is coming out of the supercritical state. It didn't work, unfortunately. I tested this idea with the americium-241 source from a smoke detector. I will continue experimenting with CO2 ionization chambers, and it might be possible to visualize the particles with superheated liquid CO2. A helpful commenter pointed out that alpha particles will not travel very far in a fluid as dense as liquid CO2, so I will try again with a beta emitter.

In a previous video, I used a stainless steel water bottle as a pressure chamber to add argon and carbon dioxide to beer. This time, I used pure CO2 to carbonate some apple slices. They're very tasty! http://www.evilmadscientist.com/article.php/co2inator

I followed instructions in the silica TMOS recipe from http://www.aerogel.org and successfully produced some small pieces of aerogel in my home shop. The two main difficulties are: 1. Getting TMOS or TEOS (the key chemical ingredient), and 2. Building a supercritical drying chamber. The components for the chamber can be bought from http://www.mcmaster.com or another source of industrial pipe fittings. You'll also need a supply of liquid carbon dioxide. I used a 20-lbs cylinder, which I bought from a local welding store. Most of the cost is in the cylinder itself, since a refill costs only $20 to $30. You may find a welding supply shop that will rent the cylinder. Getting the TMOS is difficult since chemical suppliers are generally unwilling to sell to individuals. The process to make aerogel is: 1. Mix TMOS, methanol, and ammonium hydroxide. Pour this mixture into molds, and wait for a gel to form. 2. Submerge the gel in methanol, and wait a day for the remaining water in the gel to diffuse into the methanol. 3. Discard the methanol, and replace with fresh methanol. Wait a day, and repeat. Repeat this process a few times over three days. 4. Transfer the gel into the supercritical drying chamber, and fill the chamber with methanol. 5. Add liquid CO2, then open the chamber's bottom valve to remove the methanol. Make sure the gels are always covered with liquid CO2. 6. Wait a day for methanol to diffuse into the liquid CO2. 7. Open the bottom valve and remove more methanol. 8. Repeat the methanol draining procedure while making sure the gels stay submerged in liquid CO2. Repeat the CO2 draining/exchange a couple times over 2-3 days. 9. Raise the chamber temperature to cause the CO2 to become supercritical. Slowly vent the chamber while applying heat to ensure the CO2 moves from the supercritical phase to the gas phase. Continue venting the chamber slowly, then remove the finished aerogels.

I bounced a laser beam off of a window in my house and recovered the audio from inside the room via the beam deflection. I used a Hamamatsu S7815 amplified photodiode and connected it with a 9V battery to my stereo's microphone input jack. The audio quality was very low -- probably due to the double-pane windows in my house. Speech was just barely intelligible. I also tested the procedure of bouncing a laser beam off of a framed picture that is hanging on the wall inside the room to be monitored. The reflected beam will hit a wall somewhere else in the room, and the dot can be monitored by a telescope from remote. The goal would be to measure the beam wobble via the telescope and recover the audio without needing a stringent geometric relation to the target room. This didn't work at all, but I think with a sensitive detector, it has potential. More about laser microphones: http://www.williamson-labs.com/laser-mic.htm

In an earlier video, I tried to visualize alpha particles in supercritical CO2, similar to an isopropanol vapor cloud chamber. Someone commented that the alpha particles will not travel very far (maybe 10 microns) in liquid or supercritical CO2, and recommended that I try beta particles, which should have a path length of almost 10mm. Unfortunately, I still don't see any bubble or droplet trails using strontium-90 and thallium-204 sources. It's possible that the ionizing effect of the radiation particles does not interact with the CO2 phase change as it does by condensing droplets in a cloud chamber. Also, cloud chambers are very finicky, and if this CO2 visualization method is as finicky or worse, it may take some more time to figure out the right combination of environmental variables.

This is a description of a simple opamp circuit that will translate the variable resistance of a Flexi-Force sensor into an analog voltage and maintain linearity across the sensor's measurement range. http://www.tekscan.com/flexiforce.html http://www.national.com/ds/LM/LM124.pdf Your feedback and topic suggestions for future tutorials are welcome.

Every so often, internet news aggregator sites run a story about a research group that put an LED into a contact lens, then inserted it into a rabbit's eye. I figured that I would try the same thing, but put the lens into my own eye. I accomplished this by laminating a coil of wire and an 0402 surface-mount LED between two ordinary soft contact lenses. I was hoping the lenses would stick to each other, but they did not, so I ended up fixing the edges together by pinching the plastic together with hot tweezers. This held well enough to capture a minute of video with the LED illuminated in my eye. For video purposes, I mounted the LED facing outward. An actual VR/AR display would have the LED facing inward. I powered the LED by using a very primitive spark-gap transmitter built from a mechanical relay to send RF energy into a larger coil held near my eye. The large coil coupled the energy into the contact lens coil and pulsed the LED. http://nextbigfuture.com/2011/11/single-pixel-contact-lens-display.html http://www.cs.uic.edu/~kenyon/Papers/Soft%20Contact%20Search%20Coil.Vision%20Research.Kenyon.pdf

I finally succeeded in extracting caffeine from green coffee beans by using supercritical CO2. I built a high pressure chamber from 2" steel pipe fittings, and poured in 200mL of water. There is an aluminum screen above the water line, which held 0.75 lbs of moisturized green coffee beans in the upper part of the chamber. I added liquid CO2 to the chamber, then closed all valves and raised the temperature, making the CO2 pass into the supercritical phase. I left the system overnight at about 60*C, 3000 psi, then drained the water. It was very black due to impurities and some bean burning that occurred where my electric strip heater caused localized overheated zones in the chamber. The water was highly caffeinated, and tasted somewhat like coffee. I used a typical hydrocarbon extraction process to isolate the caffeine from the water (will show this in a later video).