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The Music of the Protons

Paul Horowitz performing the nuclear procession experiment.

I just stumbled across this gem of an old video from MIT. It was made between 1983 and 1984, and stars Sidney Coleman, Ed Purcell, Paul Horowitz, and Isaac Silvera.

I’m a huge fan of Paul Horowitz, his Art of Electronics books have taught me much of what I know about electrical engineering. There isn’t a lot of info about him online, he seems to mainly keep to himself despite being a celebrity among electronics nerds.

The experiment they are performing is described in more detail at the bottom of this page: http://hyperphysics.phy-astr.gsu.edu/hbase/Nuclear/nmr.html

A large magnetic field is applied to a sample of hexane (a straight chain hydrocarbon with 6 carbon atoms and 14 hydrogen atoms) which causes 1 in $latex 10^{7}$ of the protons to align with this strong magnetic field. Once the field is turned off, the protons precess around the earth’s magnetic field. They do this at the Larmor frequency of approximately 2-3kHz (https://en.wikipedia.org/wiki/Earth%27s_field_NMR).

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Dusting off my Radio Telescope

Got out my little radio telescope that I built but never used.

I’m using a raspberry pi 4 now. For testing, using RealVNC is very nice. It let’s you view the desktop remotely. Eventually I’ll probably want automated collection/pointing/recording data for which a Python script would be best. But for now just logging in with RealVNC works well.

To install the rtl-sdr stuff, it is actually really easy. I started building from source, then realized you just need to do $ sudo apt-get install rtl-sdr

pi@raspberrypi-tx:~ $ rtl_test
Found 1 device(s):
Using device 0: Generic RTL2832U OEM
usb_open error -3
Please fix the device permissions, e.g. by installing the udev rules file rtl-sdr.rules
Failed to open rtlsdr device #0.

Likewise to install GQRX you can just just go to add/remove software and search for it.

You can search packages by name with

pi@raspberrypi-tx:~ $ apt-cache search gqrx
gqrx-sdr – Software defined radio receiver

The driver from Adafruit has changed for the accelerometer. I’m still using the old depreciated one.

I installed Cheese, then could hook up a USB webcam to verify the dish pointing.

Would be cool to allow other people access, need to figure out a safe way to do that. VPN?

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Bauch & Lomb 7×35 Binocular Repair

Click on this image gallery to follow along with the exciting repair saga. I bought these old binoculars for $12 years ago. One of the eyepiece double lenses had become impossible to see through. It was held together with Canada Balsam that had yellowed, and I took it apart by placing it in boiling water for a few minutes then sliding the two pieces apart. I almost gave up and threw the binoculars away, but then on a whim I bought a bottle of Norland optical adhesive #63 from Edmund optics for like $35 to glue the two halves of the lens back together. With that much money invested, I now felt like I HAD to get these things working again. Everything went smoothly, except losing some of the tiny set screws, and forgetting which side of the lenses was front and back (found out yes this does matter). Put it back together and everything looked terrible, very distorted. Switched all the lenses front to back and reassembled and viola! Now the image looked good. Note to future self, keep track of lens orientation and don’t drop the little set screws!

This is what I started with. I wasn’t sure I was going to remember how it went back together.
First step, clean the prisims.
A screwdriver that fit better would have helped. The slot was very narrow, and made of soft brass metal. I broke at least one screw.
Noticed one of the prisims had a chip missing, but the chip was still held in place by the mount.
Decided to try gluing the chip back on with my Norland Optical Adhesive #63 and curing with UV.
Not too bad.
Before cleaning the prisims.
After cleaning.
Now to this lens. I put dry erase marker on the surfaces to check the fit (they only fit one way)
Then I put a big gob of Norland #63 and pressed them together, wiping the excess off.
Apply the UV light to let it cure!
Put the prisims back in (they have little positioning posts that stick down)
Screw the tube in.
Retaining screw goes in first…
Then this focus wheel…
Lastly the moving eyepiece holders.
Eyepiece goes together. Ignore the lens, it is backwards and the other eyepiece lens isn’t shown.
And front lenses.
Doesn’t look too good. Very distorted.
Some random diagram from the internet. Let me try orienting the lenses as it shows. The eyepiece needs to have the more curved faces pointing inward, and the object lens has the more curved face pointing to the target.
Ahh, much better.
Done! I lost two tiny set screws, so I left all them out. Just means eyepieces can come unscrewed.

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The Effects of Nuclear War

http://www.princeton.edu/~ota/disk3/1979/7906/7906.PDF

The_effects_of_nuclear_warDownload

This study was made in 1979 in response to a request from the Senate Committee on Foreign Relations. They wanted to understand what the effects of a nuclear war would be on the United States and the Soviet Union. What I found interesting is the Appendix C. It contains a fictional account written by Nan Randall of what would happen in Charlottesville, VA in the aftermath of all out nuclear war. Pretty crazy stuff. I can’t help but feel the outcome would be even more grim today, forty-one years after this was written, because of our increased reliance on technology.

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Mapping Radiation with a Raspberry Pi GPS Scintillation Detector

I just posted a new YouTube video about I project I’ve been working on for some time. It’s a scintillation detector coupled to a Raspberry Pi that lets you make maps of background radiation levels. You can leave it in your car as you drive around town and then upload the data over WiFi when you get home.

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How Gas Regulators Work

I just posted a new video to YouTube that talks about how gas regulators work.

I’m still figuring out the whole process of making a video. In particular, I’m trying to figure out the best way of doing the audio. I tried using a microphone that connects to my phone and lets me record my voice, but if the phone’s screen turns on while recording it starts picking up a lot of electronic noise.

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Bob Wildar’s Introduction to Semiconductor Devices

I recently came across the PDFs of Bob Wildar’s Introduction to Semiconductor Devices in the Computer History Museum’s digital archive. I haven’t read them yet, but from glancing through chapters 1 and 2 I’m really excited. I’ve been looking for a text that explains how transistors work, not just how to use a model to predict their behavior. While having a model is important for designing circuits, I really want to have an intuitive understanding of what happens inside of a transistor that allows it to act as an amplifier. I love “The Art of Electronics”, and while it tells you pretty much everything you need to use a transistor, it doesn’t really get into what is happening inside of a transistor (other than the famous transistor man).

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Interesting Answers to Quantum Mechanics Questions

Why are Operators Used in Quantum Mechanics?

This post can be found here: http://physics.stackexchange.com/questions/77275/why-do-we-use-operators-in-quantum-mechanics

 Q:
In classical mechanics, physical quantities, such as, e.g. the coordinates of position, velocity, momentum, energy, etc, are real numbers, but in quantum mechanics they become operators. Why is this so?

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