Wednesday, December 13, 2017

Online circuit schematic design and simulation

This is pretty cool, although I haven't actually had a chance to use it since most of my circuits don't involve much signal processing and are quite simple DC circuits. However, LushProjects has this circuit simulator that is completely online and free to use (unlike SPICE). The neat thing is that you should be able to embed your own circuit onto any web page using this tool and iframe.

Tuesday, December 12, 2017

Hard puzzle with an easy solution

I've been keeping this tab open on my browser because I wanted to work out the solution myself. I finally figured it out (2 years later). Don't give in and look at the solution without giving it a good try. Hint, you can do it without any trigonometric functions and without Pythagoras' help.

This is known as Langley's Adventitious Angles. And a good visual solution can be seen here (warning Flash required).

Monday, December 11, 2017

Boolean Arithmetic

I had to explain Boolean arithmetic the other day to non-makers. These guys didn't have any real experience with electric logic circuits, but the pictures here seemed to help.

Friday, December 8, 2017

Prusa's ColorPrint tool

When 3D printing, there's usually a jump in cost and complexity for printers that can print multiple colors. As a workaround, you can pause the printer, switch the filament to a different color, print a few layers with that different color, then pause, switch filament, then resume printing. This can be a very tricky thing to do manually, so obviously, there is a tool to do it.  Here are some prints by a buddy of mine that utilized this tool for these prints. He prints a black surface with a cutout for the image, prints a few layers of a different color (glow in the dark in this case), then resumes printing in black. He didn't have to design the model with any major modifications, just the first few layers cut out so that the glow in the dark layer can shine through.

Thursday, December 7, 2017

PiVPN

Rolling your on VPN can have various benefits. The biggest of which is that when you're on an unsecured network (i.e. any wifi network that you don't own yourself) your traffic is encrypted back to your home and then goes out to the internet. This means that you don't have to trust that the WiFi owner (think Starbucks or McDonald's) isn't snooping on your packets. It doesn't matter if they do snoop it because you're packets are encrypted and nobody can understand it unless they are you or your RaspberryPi at home.

Before you contest, yes, I know that any form of encryption can eventually be beaten. If you're that paranoid about someone decrypting your packets (which would take years by the way) you should be off the grid.

That said, I looked into setting up a VPN option for myself and eventually found PiVPN. This little one line installer sets everything up on your RPi so that it becomes a VPN endpoint. Use it to generate a certificate which you can load on your device (I've tested on iOS and Windows 10) into the freely available OpenVPN client.

I have since found, but not installed/tried a web GUI that should let me manage PiVPN through a browser. I hope to try this eventually after I have some free time. So, probably next year!

Wednesday, December 6, 2017

Sense HAT Data Logger, my version

I ran across this project and decided to give it a try. Without actually trying it out on a physical SenseHAT, I simplified the code down to this:

Tuesday, December 5, 2017

PressPi

I wanted to figure out the best way to put WordPress on a RaspberryPi. Turns out the best way is an image called PressPi. Load this up, lock down all the security, load CertBot so it's all running over https and you're good to go.

In case you're interested, here's a good set of instructions for installing Wordpress on Ubuntu 16.04. So many instructions! You might need phpMyAdmin as well.

Monday, December 4, 2017

HTML Maps

I recently needed to overlay a bunch of links on top of an image. This is done one of two ways, CSS being the more modern way. Essentially, you create a div with a bunch of elements inside it, which elements are all positioned absolutely.

<div style="position:relative; height:786px; width:537px; background:url(myimage.png) 0 0 no-repeat;">
     <a style="position:absolute; top:393px; left:147px; width:87px; height:69px;" title="asdf" alt="asdf" href="asdf" target="_self"></a>
</div>

Instead of mapping out all the positions manually, there's a really neat tool that will let you do it right on top of your own image and then generate both the HTML map code as well as the more simple CSS code to render it on a webpage.


Friday, December 1, 2017

W3Schools and their incredible CSS Library

Anyone who has built a website in recent history knows the importance of good CSS. I myself have been compiling a master CSS sheet that I use on most of the web development projects I'm involved with. I realized that I was trying to accomplish the same set of outcomes over and over, so a standard library of CSS styles was a natural shortcut to a good end.

I know some have been critical of W3Schools.com and their no nonsense way of explaining web development concepts, citing technical inaccuracies and nuances. I've found that those perceived inadequacies either can't be discerned by "normal" people or don't have a discernible impact on the end product. As such, I've been a fan for a couple years now. I've built their site into my Google searches so that I know I'll end up going to the answer that I'm sure they've provided straightaway.

I've used a few of their tools from the CSS section over the last few years, particularly pleased with their tooltip implementation. That's when I discovered that the CSS sheet that they use for their own site, which has all of the CSS needed to implement all of the cool, modern utilities is free to use. They even encourage it!

There are a couple things I like about it:

  1. All their examples use this single sheet. I don't have to understand a concept, then look up a different place to find out how to use the W3.CSS framework to implement it. 
  2. It uses pure CSS. I only include one CSS reference and I'm good to go. There's no need to import a jQuery/javascript library as well to make it all work.
  3. It treats responsiveness and mobile first as the highest priorities. This is what makes simple websites look like websites developed my multi-billion dollar corporations.
  4. Templates!
I used one of the templates here. It's one page. I don't host any javascript nor CSS files. Even the icons are used from frameworks referenced and explained by W3Schools.

Thursday, November 30, 2017

Installing LAMP in one step

Go educate yourself on LAMP.

Installing LAMP has been getting easier over the years. Now you can install it with a single command line:

sudo apt-get install lamp-server^

More information here.

Encryption Everywhere

Anybody who has stood up a web server knows the importance of securing that connection. Watch this video:


While I don't yet use the HTTPS Everywhere add-on, I do make use of Certbot. You can see an example here. This website runs on a LAMP server on AWS (the free tier). From beginning to end, except the coding of the site itself, I had the secured site running in about 15 minutes. Several cool things happen when using Certbot:

  1. It's aware of the multiple hosts you may have configured in your web server and lets you run for specific hosts.
  2. It automatically configures http redirect. This means that even if a user accidentally left of the https:// from the address to your site, they'll get redirected to the https version automatically. When I first did this manually, it took me several days to get it working right. 
  3. The certificates are free because they have a short life span. So, Certbot has to be run regularly to get a new certificate. You don't have to pay attention to that cycle though because you can run the checker daily or weekly and it won't do anything unless the existing certificate is close to expiration.

Mini blog posts

Since I don't really have the time anymore to do long, in-depth blog posts, I've decided that I'll start doing mini posts with tidbits of information. When I started this blog, it started out as a place for me to post stuff I needed to remember and/or have a place to right stuff down that I could recall easily. This is a continuation of those efforts. I'll be picking suspended Chrome tabs and detailing why I've kept that particular tab around.

Tuesday, September 12, 2017

Hurricane Harvey - Our Story

Hurricane Harvey started affecting us Friday, 25 AUG 2017.  It was my Friday off, and we were preparing for the next Monday when the twins would enter kindergarten. As such, Friday was "Meet the Teacher" at their school. The sky was dark and there was light rain. It felt like a good day to cuddle up and watch a movie. Friday evening, I was in touch with our ward leadership as we coordinated our response teams.
Our band is to perform on 9 SEP, so the next morning (Sat 26 AUG), Christy and I got together with the rest of the band and had practice over near Black Horse Ranch. We were finishing up with the first set as the bottom fell out so we decided to break. We were across Cypress creek from our kids and we wanted to make sure we got back to them before any flooding started. We had identified some friends of ours who were in a neighborhood near us that was likely to flood. They were preparing to move out the following Thursday (31 AUG) so they had most of their stuff in boxes already. She (Kelia) is almost 9 months pregnant so it was agreed that they would preemptively evacuate to our home. On the way home, we went over and helped him (Kris) lift some of their furniture onto blocks and 2x4's. They had a few other things to finish and he has a large pickup truck, so we left them to finish expecting them to come over later in the day. They could get out even if the flooding started. It's important to note that their neighborhood usually floods before anything else in the area and when the flooding is really bad, their neighborhood dumps out into our neighborhood. As long as they are not flooding into us, we don't have a problem draining our neighborhood.
They came over later that afternoon and the kids started playing. We got them setup in our spare bedroom with bunk bed cots for the kids (4 total people in that family). Kris and I went back over to his neighborhood. He went back over to the house to get a few things they had forgotten and I went to help another friend attempt to waterproof his garage door. We jammed some tarps into the hinges of the garage door and weighted it down with landscaping bricks. This turned out to be a pretty good barrier against the water that eventually rose a couple feet above the bottom of the garage door. When we returned, there was only water in the street gutters. A few hours later, water had risen to cover the street. We started keeping an eye on things. The reservoir we drain into was well below us, so I wasn't worried that flooding would get to dangerous levels for us. The last two major floods had not produced enough water quickly enough to have it come up more than halfway up the driveway.

Sunday morning (27 AUG) dawned with some water covering the streets, but less than the highest point overnight. The other friend in the same neighborhood that always floods first had not yet evacuated. The overnight rise of water had not receded so they were looking at evacuation options. Kris and I rode in his big truck and started to prepare their house for flooding and to convince them to evacuate. It became evident that the water was going to keep rising. Last year, this family had waited until it was too late to evacuate during the 2016 tax day flood and had to be evacuated by canoe. We emphasized how important it was to avoid getting to that point again. The father wanted to wait it out, so we took the mother and kids to another ward member's two story home which was serving as a dispatch location for the emergency crews. The father was left to his own devices to get out (which he eventually did on his own).
A large number of ward members had congregated at that two story home for a previously scheduled baptism. Since extended family had flown in for the event, it was decided that the baptism would be performed not at the presently closed Eldridge building, but in the pool in the rain (pretty memorable!). Since there was a large group and the Bishop was present, it was decided that the sacrament would be administered since all other church meetings were cancelled. Shortly afterward, the rain lightened up and most of our street drained.
Sunday afternoon, a rescue request came in for a family in Enchanted Valley. It was outside our area of responsibility, so our dispatch tried to find resources in the area. Unfruitful, he dispatched Scott with his big Yukon. They made it to the family and loaded everyone up. There wasn’t room for two of the four rescuers, so they stayed behind to be retrieved after dropping off the family at a safe location. Upon returning, Scott decided to splash around a little and stalled his Yukon. They pushed it up onto dry land and notified our dispatch. I saw that call come in and reached out to a few Jeeper groups who had been offering help and making rescues since the rain started. Allan and Z responded and we headed out toward Telge and 290. I made it past the Sheriff station before the water started getting deeper. I gave Allan and Z my tow strap and they continued on (they have a few inches more clearance than I do). Their two door jeep would only hold two of the four rescuers, so Scott and his nephew stayed with his truck while the two who had originally stayed behind were brought back to me. I had backtracked and waited under the 290 bridge at Telge. Upon returning, the water had risen. Allan commented that he could probably make it back in, but he was worried about getting out while the water was still rising. We decided to attempt to rescue via Huffmeister. It was dark by this time. In my lower Jeep, I led the charge. The streets were clear of water until about a half mile north of Cypress North Houston. I was cruising at about 40mph when we hit the water. Needless to say, it was a pucker moment. We were all fine, but it was one of those moments where everything went into slow motion. The water started getting deeper, so again Allan in his swamp thing went ahead to see what they could see. The water ended up being too deep (reportedly about 6’) so, we weren’t getting to Scott and his nephew any time soon. They would have to ride it out. The rain started coming down harder and we had just received news that the Addicks and Barker reservoirs would be opened up at 2am. Not yet knowing how this would affect the current water levels, we decided to break for the night.  We went to bed late Sunday night as we watched the waters begin to slowly creep over the street in front of our house.

Monday morning (28 AUG) when Christy got up, Kelia told her the water outside, which was up to the sidewalk, was no longer draining away.  Christy insisted that we start making plans to raise our important possessions and make an evacuation plan. I was hesitant because of past experience with extreme flooding had never given us any problems. I reluctantly conceded though and we figured out what we would do if we decided to evacuate.
We found out that the neighborhood that always floods first had breached the main road and was spilling into our neighborhood. It wasn't going to get any worse for them, but it was coming in quickly enough that our drainage system wouldn't be able to keep up for long. I went for a hike in my chest waders and saw our main drainage creek rising. This meant that what we were draining into was full and it was only going to get worse from here. This had never happened before. It turns out that the Addicks reservoir had filled up. <a href="https://www.usatoday.com/story/news/nation-now/2017/08/28/controlled-release-water-houston-reservoirs/607594001/">The Army corps of engineers had already opened it up to drain it</a> (which would send the water south toward the ocean) but the water leaving was less than what was coming in. I broadcasted my hike live over Facebook (https://youtu.be/-XQDWJn-1Tw). Upon returning home, I had decided it was time to get out while the water was low enough for my Jeep and Kris' truck. Our neighbors (4 adults and one infant) also needed to evacuate. We rallied everyone into motion and started implementing our plan. We got everything that we could think of up a as high as we could. Kris and I loaded our vehicles with the essentials we would be taking with us. I got my family loaded up in my Jeep and Kris got his and the neighbors loaded up in his truck. My neighbor got 3 videos of our escape (part 1, part 2, part 3) from the back of Kris’ truck.
My Jeep dove into the water and got us to a high point right before the exit of the neighborhood onto Barker Cypress (which was the spillover point for the first neighborhood that flooded). I parked there and we made sure the boys had their life jackets on and seatbelts off (in case we had to ditch the Jeep). About 8 minutes later (which seemed like an eternity) Kris' truck caught up with us and we pushed forward into the deeper water right before the exit onto Barker Cypress. It's at this point that I think I got water in my differential, more on that later. With no option but to push forward, we got water up to top of the Jeep tires before making it out onto the shallows of Barker Cypress. We turned south away from Cypress Creek and away from 290 where the water was coming from. We made it down to Tuckerton without any real issues except for some water up to the middle of the Jeep tires. It was dry from there on out. My plan was to head Southwest until we found a place to land. While en route, James, a fellow Cub Master, texted me offering to let us come to his place indefinitely, which we did. His neighborhood was wet but didn't have any water on the streets. I realized later that we were living out the story of the three little pigs, Kris' family fleeing the straw house from the big bad Harvey to our house of sticks, which we eventually fled to James' house of brick.
I spent most of Monday afternoon coordinating rescues, surveying potentially flooded/closed streets, and making various runs to the Longenbaugh Mormon church, which had been turned into a shelter. There was a ton of food and other donations to be received and sorted as well as families to take care of. I got a call later in the day asking to help with evacuation of a family of 13 near the intersection of Queenston and Tuckerton. I made it to the Shell station there, which had turned into a staging point for various high clearance vehicles that were going in to make rescues. I arranged for an ATV with a flatbed trailer to make the run into the house where the family was. They would bring them out to me and I would take them to a shelter. After the ATV was dispatched, they family called and cancelled. I still feel bad for the driver of the ATV. I got signed up to do a shift on Tuesday from 4-8pm at the Longenbaugh building. The shelter required two Elders or High Priests present at all times.

Tuesday morning (29 AUG), Christy and I ventured out in the Jeep to try to make it back to the house. Several reports on our neighborhood Facebook page indicated that the waters were receding. We found high water on Red Rugosa, but not too much covering the street in front of our house. We discovered that the water seems to have entered the garage and gotten to the front porch, but didn't come into the house. We also found a telephone/electrical pole which had been parked at the end of the street waiting to be installed that had floated into our front yard. This was surprising, but not unreasonable. It was wood and the water was high and apparently thrashing towards the three storm drains in front of our house. Some neighbors saw it churning around and lashed it to one of my trees. Christy and I elevated a few more things in case the water came up some more. I built a couple of impromptu sandbags out of wet towels, garbage bags, and landscaping bricks to put at the front and back doors. I spent the afternoon at the Longenbaugh building. The clouds moved off, the sun shone. It felt like a good sign that the storm was over. There was a rumor about a kicked in door across Barker Cypress, so I decided that I would spend the night at the house with my shotgun. It also gave me a chance to watch Guardians of the Galaxy 2.

Wednesday morning (30 AUG), our roads were dry and we had decided that we could probably come back to our house from James'. The sun had started to shine and only the lowest intersections still had water. Harvey had moved on to east Houston, so while we were technically still in the storm, we were now on the dry side. We came back home and started to put things back down on the ground. I spent the afternoon loading up small items from Kris’ house and being a shuttle driver for the ward team that was gutting a home. I eventually got some food brought in for the teams in both locations.

Thursday (1 SEP) we spent most of the day moving Kris and his family into their new home. The roads were dry, so it was a simple matter of loading up the U-Haul twice. Their new home is less than a mile away, but on our side of Barker Cypress (less chance of flooding).

Friday (2 SEP) I spent the morning getting some things back in place around the house until my brother, John, came in from Dallas. When he got here, we got together with the ward team to work on removing some wood flooring from a flooded house. That took the rest of the night and we only got the main living room (150/1200 sq. ft.).

Saturday (3 SEP) I dropped my brother off with the team that would continue for the next six hours working on that wood floor. I had arranged to attend a differential fluid changing party hosted by a shop owner on Clay road just inside the beltway. They were changing fluids for free, so it was a good opportunity to make sure everything was in working order and also make sure I got the water out of my gears. They also gave me some pointers which made installing the wiring harness for my trailer hitch dead simple. I got done with that around 1pm and went to act as a coordinator for the team that was finishing the wood floor removal and the other team that had begun gutting another house.

Sunday (4 SEP) began with gutting a few houses in our neighborhood. We had abbreviated church meetings at 1pm during which a new Bishopric was called and we were notified that we would be meeting back in the West road building for the foreseeable future.

Monday (5 SEP) was Labor day and our crew chief had advised that those of us who had been working for several days straight take some time off to recover. I heeded that advice and played with the kids. I brought out the slot car track and we raced. In the evening, grandpa invited us over to go fishing. He had just bought three new kids fishing poles (Star Wars themed, of course). Luke caught a baby brim and a baby bass. I caught a turtle and Grandpa caught a brim and another turtle. We let the first one go, but decided to relocate the second one since the turtles have a tendency to kill the ducklings. Cole became an expert caster, sometimes throwing his practice weight 25 feet from the shore.

Tuesday (6 SEP) meant a return to work; the Chevron offices had been closed since the storm. It appears the tunnels were flooded since the demo work had already been done and there were dozens of fans and dehumidifiers.