Halloween 2022

This year, we had a small turnout: only 22 kids, which is even less than last year’s small number.  We were not very ambitious in our decorations either.

I put the old packing-tape head sculpture on top of a pumpkin with 42 holes drilled in it (using 3 different sizes of Forstner bits).

The same 4-board strobe light that I used last year was inside the pumpkin lighting up the holes and the head, for a somewhat sci-fi look. I had the idea of putting the head on the pumpkin, but my wife was the one who suggested doing an abstract theme for the pumpkin itself. (The picture is a bit shaky, because I was too lazy to get out a tripod.)

My wife went with a more conventional carving.

She also had the carving conventionally lit with candles.

Our skeleton (Kyle) has been in the dining-room window since last year, but I put in the flashing lights again and gave him a cap.

I tied a rather random web this year and lit it with a UV LED strip. I apologize for using a non-web-spinning tarantula as the spider, but it was the only big spider toy I had.

My wife put all her Halloween effort this year into her costume as Puss in Boots. She works at an elementary school, so is almost required to wear a costume. They are not permitted to have weapons or gore as part of their costumes, so she substituted a feathered cat toy for the sword that Puss in Boots would usually have.

Halloween 2021

This year, we had a fairly modest Halloween, after not celebrating it all last year.  We had only 36 trick-or-treaters, about the pre-COVID normal number, but way down from the glory days 15–20 years ago, when we could get 120.  We harvested over 30 volunteer decorative gourds from the area around our compost heap, and we added two purchased pumpkins that we carved.  I also bought an anatomically correct PVC skeleton this year (if we’re going to have a skeleton in our closet, it should at least be a good one).  I did not make a spiderweb on the porch railing this year, nor did I get out the UV LED strip—just too lazy.

Here is a small pile of a few of the gourds.

This frowning pumpkin is the one I carved. I went for a minimalist look—cutting off one side of the pumpkin, drilling 2 1″ holes with a brace and bit, and 5 cuts to make the mouth.

Another view of the frowning pumpkin.

The frowning pumpkin with the stroboscope inside. The strobe worked quite well—it helped that I had sloped the drill holes for the eyes somewhat.

My wife carved a thinner-walled pumpkin. It turned out to have a soft spot, so she had to make the eyes quite large—the lemon slices made quite effective irises.

A candle in the lemon pumpkin lit the eyes well.

I liked this gourd best—I called it the Harry Potter pumpkin.

The porch showed off the two carved pumpkins and the gourds.

Once it got dark, the porch light lit up the skeleton and the gourds, without detracting from the strobe and candles.

The mini-strobe that I used is the same hardware as in the 2016 Halloween strobe, but with only 4 of the LED boards, instead of 20. I bent some solid copper wire to hold the boards, with the wires just held by the screw connector.

The skeleton, which my wife named Kyle, hung in our breakfast room window for most of the week before Halloween, but was moved to the dining room for Halloween itself. The male name is appropriate, as Kyle’s pelvic bone has a male conformation.

Here is Kyle from the side on his rolling stand (rather than hanging by a thread). You can see the black USB cable coming out of the foramen magnum just behind the atlas (C1) and axis (C2) vertebrae.

A closer view of Kyle’s skull, with a KitKat between his teeth and the hanging cord and USB cable both visible.

Kyle on his stand in the dining room window—not very clear during the day because of reflection, though his red eyes are somewhat visible.

Inside Kyle’s head, showing his “brains”: a Teensy 3.1 board, a couple of 150Ω resistors, and a board with two LEDs behind the eye sockets. The board was program to alternate blinking the eyes every couple of seconds, alternating that with a random action (winking left, winking right, blinking, … ).

The LED board wedged in firmly in the sella turcica between the anterior and posterior clinoid processes.

I had to cut away a lot of board to get the LEDs to sit directly behind the superior orbital fissures. The LEDs themselves are LTL307E LEDs, which take about 20mA at 2V, and the 150Ω resistors limited the current to about 9mA, which is what the Teensy board can supply on each pin.

Now that we have this fine skeleton, we’ll probably keep it on display in the living room, but only light up the eyes for Halloween.

Dropping old LED lighting project

About 4 years ago, I started a project to replace the breakfast room ceiling fan (which my wife has always hated) with an LED fixture of my own design.  In order to do this, I designed some custom LED boards that could work over a range of voltages with PWM control of the brightness and I made some desk and table lamps using the boards, as well as a stroboscope (Summer project, LED board I-vs-V curve, Summer project 2, Desk lamp, Newer dimmer software, LED strobe using dimmer board, Halloween 2016, … ).

Although I have had the electronics done for the breakfast room fixture for about 3 years, I’ve not been able to come up with a mechanical design that I think will look good.  Also, the task of cutting the conduit in the attic to install an outlet for the wall-wart power supply did not appeal to me, so I kept putting off the project.

Last weekend, my wife, my son, and I went to the local Habitat for Humanity ReStore, ostensibly to look for cabinet handles and doors, but mainly just to browse. While there, we saw a used drum light ceiling fixture that was on sale for only about $16 (it is one that normally sells for around $120 new from Home Depot).  Since I had pretty much given up on coming up with a design using my LED boards that would look good, and my wife liked the drum fixture, we bought it and my son helped me install it.

The hardest part of the installation was probably pulling new wire through the conduit, since I did not want to use the old cloth-covered solid copper wire that was there.  I also added a grounding screw to the junction box for the lamp, since the old ceiling lamp had no ground connection.

Here is the “new” ceiling lamp in daylight.

Here is the ceiling lamp with 3 2700K LED bulbs.

Lining up the screw holes of the fixture with the screw holes of the junction box was also a bit tricky—my son’s holding the fixture while I fussed with that was a big help.

The whole project cost under $30: $16 for the fixture, <$3 for screws and wire, $7.50 for 3 LED bulbs. The new lamp is not dimmable (because of the cheap bulbs I chose), but that feature was not really needed for the breakfast room anyway.

So I now have a lot of spare LED boards that I need to find a project for—I’ve used a few of the boards for the desk lamp and stroboscope projects, but I don’t really need another desk lamp or stroboscope.  Anyone have any ideas?

Halloween 2016

Halloween was a bit of an impromptu arrangement this year. I was at the iGEM Jamboree all weekend, and my wife and I only got home from Boston a little before 7 p.m. on Halloween, so we did not have time to carve a pumpkin this year.  Instead, I decided to improvise a very fast pumpkin surrogate:

First, I found a cardboard box large enough to hold the LED stroboscope that I had made for the mini Maker Faire.

Then I cut out a stencil pattern from a piece of heavy paper.

I made one mistake when cutting the stencil, cutting away the opaque center for the lower part of the B. I just used blue painter’s tape on the back of the paper to stick the piece back on, and recut the B.

Initially, I tried taping the stencil over the opening in the box, but the light was not diffuse enough—the individual LEDs were visible and the stencil pattern unclear. I then tried taping the stencil to the cutting mat and taping the cutting mat to the front of the box. It wasn’t very secure (painter’s tape is not very sticky—by design), but it worked for the evening.

The final result looked much better in the window than a 20-minute project had any right to.

First week’s grading done

I spent all day Sunday grading the first set of lab reports.  I was expecting 24 reports of about 3 pages each, but I got 25 averaging about 5 pages each.  I think that the reports were a bit better this year than at corresponding times in previous years, but I did not get my grading done until almost midnight Sunday night, keeping me from getting much else done this weekend.

(I did manage to get my hair cut and to build a new strobe stand with room for 20 of my LED boards, which should give 1800 lumens during the flash. With a duty cycle of only 1/65, I don’t think that I need heat sinks on the boards for the strobe, as the average current should be only 40mA, though the peak current will be about 2.6A.)

In class on Monday, I gave students some group feedback on their writing, plus a couple of pointers, then took questions, some of which were about writing, but most were about the optimization of the fixed resistor in the voltage divider for the resistance-to-voltage converter in the thermistor lab.  I showed them how to set that up, but did not try to solve it in class.

After class, when I was making up the key (redoing all the problems—I don’t like just looking up results—refreshing my memory on how to solve the problems by resolving them is best), I ran into a little trouble doing the optimization. I used to be able to just ask Wolfram Alpha to solve the differential equation, but their newer parser seems to be much harder to convince to do anything.  I eventually gave up and used a cruder tool to just take the second derivative and solved for the resistance by hand.  That was faster than the time I wasted trying to get Wolfram Alpha to do anything useful.  (I suspect that they have deliberately crippled it, to make people pay for Mathematica.)

Monday afternoon and evening (from about 1:30 to 7:45) was spent grading the first pre-lab homework.  Again the results are a little better than previous years, but there were 9 prelabs fewer than I expected (3 students have dropped already and 6 did not do the prelab).  I hope that those who did not do the prelab were just confused about when it was due, and not starting a trend towards coming to class and lab unprepared. I also hope that no more students drop—this class is not a weed-out class, though it is a lot of work.

Back in January, Mike wanted to know where I ended up doing my grading. Sunday I did my grading in my breakfast room, with the laptop on the floor where I could get to it if I really needed to look something up, but where it was not a constant temptation to goof off.  On Monday, I worked in my office on campus, where the e-mail was a minor distraction that I checked between problems.  (For the prelabs, I graded the entire stack for problem 1, then the entire stack for problem 2, and so forth.  This makes for more consistent and faster grading than grading a student at a time, but it would be faster still if the students didn’t put their answers in random order on what they turned in.) I’ll probably continue with weekend grading in the breakfast room and prelab grading in my office until the distractions get to be too much—then I’ll look for a coffeeshop to grade in.