So I recently had the idea of asking folks for a book recommendation. The way I phrased it was, 

1. Since I was providing a bunch of Amazon links, I took it as an opportunity to embed a Amazon Affiliates tag. If you click and buy, I get a kick-back. I hope everyone believes that this is not the main motivation behind the list. I’ll be happy if I get $10 or $20 out of it. Enough to buy one of the books on the list
2. I’ve tried to make everyone’s name identifiable yet not have it show up on a google search. If you know the individual, you’ll probably recognize the name I attached.

Dawn’s Early Light Elswyth Thane

32. Silvija
The synagogue of Satan – Andrew Hitchcock

During the school year, I volunteer on Saturday mornings wit Mind Matter helping local underadvantaged high school kids prepare to take the SAT. One of my students will be going to Wellesley college next year. I’m very excited for her and it brought back lots of awkward, but very fond old memories. I felt inspired to pass some wisdom on to her and I wrote down some words of advice.

This post is dedicated to some of the wonderful MIT and Wellesley women I’ve known (by initials): CT, JW, LG, JB, KR, DC, KB, and CO (though I only met you after graduation)

1) College is one of the best times of life for many many people. It’s a time to explore who you are, have some fun, experiment, and enrich your mind in a way you’ve never done before.

2) Academics is the main reason for college, but it’s not the only reason. Do other stuff. Explore the area where you’re going to school, take a ballroom dancing class, participate in athletics (intramurals in particular). Meet people.

3) If you choose to drink, know how much your body can handle. Take notes. X beers == buzzed. Y beers is too much. The only differences between drunk and really drunk are:

a. The hangover you have in the morning

b. You embarrass yourself by being sloppy drunk.

4) I recommend you stay away from other drugs. You have plenty of time in life for that. Most colleges have pot, lsd, and coke available. I know plenty who tried these and were still ok. I also know people who struggled with these. I did without and I don’t regret it.

a. A lot of people pick up smoking in school. It’s a gross habit.

5) Get to know your professors. People don’t become profs if they’re not passionate about their subject. If you take an interest in their field, they will take an interest in you.

a. Go to office hours. I did and it never counted against me. I saw it as free tutoring from top notch teachers.

6) Find study partners. People who approach things differently from you are particularly valuable. Talking through assignments really helped me.

7) Read your assignments they day you get them. This usually only takes five minutes. Read your assignments every day to remind yourself. This enables you to think about the work before you actually do it. With this method, when it came time to actually do the work, I often had to just write down the answer.

Set aside times on the weekends to study. College classes require more work than what you’re used to in high school. As an example, I had a study group of three of us. We worked on the homework on Sunday after one of the guys in my group got out of church. We alternated between the three fraternity houses that we were in.

9) College classes should be hard and require a lot of work. If this is not true about the classes you’re taking, you should consider finding something more challenging. Remember this when you’re frustrated. You should not take this as a sign that you’re not smart enough. If you got into the school you’re most likely totally capable of succeeding. A large part of college is persevering when it’s not easy. For example, the math classes I took had homework consisting of no more than 10 questions. Problem 10 was more difficult than 9 and so on down. Sometimes I just had to sit there and stare at that one problem for a while. Try different angles. This is why it’s important to read the assignments early. Gives you a chance to digest the problems. But always remember that “hard” is not the same as “can’t”. Just keep poking at it.

Wellesley specific advice.

1. I was not a student there, so I am not the final authority, but I’ve known and loved people who were (dating and as friends). Also, I’ve been out of college for just about 18 years now. Of course, generalities often don’t always apply to individuals.
2. Wellesley encourages you to find your strength. Feminism is very strong there and that’s a wonderful thing. One mistake I saw many women there make is to equate that with giving up your womanliness. It is possible to be a strong professional woman AND still be sexy, feminine, gentle, beautiful, caring, sensitive, passionate, and all those other things.
3. I encourage you to spend time off campus. The Boston area has so much to offer. Visit both MIT and Harvard.
4. I encourage you to reach out to the women of MIT. This will be difficult at times. There’s a bit of rivalry between the two groups. I’ve seen Wellesley friends of my fraternity feel like they were competing with our MIT women friends. This doesn’t have to be the case.
5. MIT women have a lot to offer that is different from what Wellesley women give.
6. Wellesley women and MIT men come together in some conflicting circumstances. Wellesley students are busy finding their strength and discovering who they are. Many of them come from protective environments and are making their way out from under that. MIT men are often less socially mature and they’re also trying to figure things out. The combination can be awkward and I encourage you to keep this in mind. Be understanding of the insecurities around you. Be aware of your own insecurities. Don’t let these things pull you in a negative direction. Use this to temper your reaction when others are behaving irrationally.

I recently happened up this article about making a sous vide immersion controller. I peaked my curiosity since I’ve had difficulty in properly cooking steaks. Once I got to reading, I found a pretty good website on cooking sous vide. So I decided to try it myself. I got a PID controller off ebay (~$20) and a solid state relay (~$6.50), wired em up to controll my crock pot and gave it a try with some chuck roast. The results were quite tender, but I need to do better on the finish. I seared it on my BBQ but I think I need to let it sit there longer.

Some implementation notes. The PID controller claims to control an SSR, but the ebay ad lied. The seller claimed to be ignorant on the products they sell, but I think it’s BS. I recommend against them. Women of the world should feel ashamed at this person (I’m just a dumb woman, hee hee) (jinpengcart2011).:

Not all was lost though. I figured out a way to wired it up for SSR control. I patched into the control signal to the relay (the red and black wires. click on the image for a larger shot):

Here are some addition photos. I still need to add wall plates.

 I’ve recently had two people ask me the same question about how I took some recent pictures. I sent them mail about it, but I figure I’d share with the two people that are subscribed to this blog

e 

I used a white sheet as the background and two 4×8 vinyl bathroom surround sheets from homedepot. probably $20 each. Note that this is easier if you have a two flashes.  I’ve considered getting a third.

Also this one:

This one I took with a black sheet:

To take the pictures with the white background, you need to flashes, but you can get a good start with just one:

$21 lightstand  http://cgi.ebay.com/200CM-Light-Stands-Photo-studio-/110694199117?pt=LH_DefaultDomain_0&hash=item19c5e36f4d
$14 bracket http://www.amazon.com/Mounting-Bracket-Strobist-Umbrella-Fancier/dp/B003TY6GWU/ref=sr_1_4?s=electronics&ie=UTF8&qid=1306780897&sr=1-4
  $5  umbrella http://cgi.ebay.com/33-Studio-Flash-Translucent-White-soft-Umbrella-83cm-/170644198871?pt=LH_DefaultDomain_0&hash=item27bb2fd5d7

$28 wireless trigger http://cgi.ebay.com/RF-602-2-4GHz-Wireless-Remote-Flash-Trigger-CANON-/250775783838?pt=Camera_Camcorder_Remotes&hash=item3a6366c99e

$68 total.

To learn how to do this, read this series of blog entries: http://strobist.blogspot.com/2006/03/lighting-101.html

This group has great discussion: http://www.flickr.com/groups/strobist Lot’s of examples of what you can do.

White background http://www.zarias.com/white-seamless-tutorial-part-1-gear-space/

while you’re at it, this blog is very interesting as well.
http://petavoxel.wordpress.com/category/megapixel-madness/ The explanation of the physics of megapixels vs sensor size.

my next flash purchase will be one of these:

he flash is this one

As part of my photography hobby, I use NiMh AA batteries in my flashes. Occasionally, it happens that my flash won’t recharge very quickly, if at all. I’d always believed this to be caused by having one or two dead/weak batteries. Most flashes use 4 cells in series. If one is no good, nothing works. Most sites I’ve read recommend always using batteries as a set. Always use the same four together. I wasn’t doing this and that’s probably a large part of my problem.

But now I have ~20 batteries of unknown condition. How to test?

After googling around a bit, I came across some Arduino based testers. The ones I found had some great features, like the ability to handle battery packs, identify batter type and more. I just needed a AA NiMh tester that could handle multiple cells. In the end, I brewed my own.

My design is pretty basic. I discharge a cell through a 1 ohm resistor. Since these batteries typically run at about 1.2v while loaded, this translates into approximately 2 hours to discharge. Since I am discharging each cell independently, I don’t need to worry about over-discharge.

The green wires measure the voltage drop across the resister which is used to track the current flowing. The code checks the current every 10 seconds and displays the milli-amp-hours. The lcd displays the four values.

The software considers a cell discharged when the voltage drops below .6v. After this when it sees a voltage above .8v it resets the data for that channel. These are probably not the best values to use, but they work.

As a voltage reference, I use 4 1kohm resisters in series and tap off of one of them. This yielded a ref voltage of 1,237 when measured with my voltmeter. I’m not too concerned about accuracy. I just want consistency to enable me to pair cells into sets of four.

Here’s the source code

#include "Streaming.h"
#include <LiquidCrystal.h>

float aref = 1.237;
int interval = 10;

// Connections:
// rs (LCD pin 4) to Arduino pin 12
// rw (LCD pin 5) to Arduino pin 11
// enable (LCD pin 6) to Arduino pin 10
// LCD pin 15 to Arduino pin 13
// LCD pins d4, d5, d6, d7 to Arduino pins 5, 4, 3, 2
LiquidCrystal lcd(12, 11, 10, 5, 4, 3, 2);

void setup()
{
  analogReference(EXTERNAL);
 
  // start serial port at 9600 bps:
  Serial.begin(9600);
  
  lcd.begin(16, 2);
  
  lcd.clear();                  // start with a blank screen
 
}

class Battery {
  public:
  enum States { EndDischarge, Discharging };
  Battery(int pinin, float res) {
    pin = pinin;
    resistance = res;
    reset();
  };

  void reset() {
    state = EndDischarge;
    as = 0;
    elapsed = 0;
  }; 
 
  float getmAh() {
    return float(as*interval)/3600.0*1000.0;
  };
 
  States getstate() {
     return state;
  }
 
  int getpin() {
     return pin;
  }
 
  void tick() {
    int val = analogRead(pin);
    float volts = float(val)/1024.0*aref;
    float current = volts/resistance;
   
    switch (state) {
     case EndDischarge:
      if (volts > .8) {
        reset();
        state = Discharging;
       
        Serial << pin << " battery connected\n";
        break;
      } 
      return;
      break;
    
     case Discharging:
      if (volts < .6) {
         Serial << pin << " battery discharged with " << getmAh() << " mAh\n";
         state = EndDischarge;
         return;
      }
      break;
     
    }
   
    elapsed += interval;
    as += current;
   
   
    Serial << pin << " volts " << volts << " current " << current << " mAh " << getmAh() << "\n";
  };
 
  private:
  int pin;
  float as;
  long elapsed;
  float resistance;
  States state;
};

Battery batteries[] = {
    Battery(0, 1.0),
    Battery(1, 1.0),
    Battery(2, 1.0),
    Battery(3, 1.0)
};

void loop()
{
  delay(interval*1000);
 
  lcd.clear();
  for(int i=0; i<sizeof(batteries)/sizeof(Battery); i++) {
    batteries[i].tick();
    lcd.setCursor((batteries[i].getpin()%2)*5, batteries[i].getpin()/2);
    lcd.print(int(batteries[i].getmAh()));
    if (batteries[i].getstate() == Battery::EndDischarge) {
      lcd.print("d");
    }
  }
}

So I’ve been wanting to build the Gingery series of metal working tools, starting with the lathe. As part of that, I’d need some v-belt pulleys. I could buy them, but that seems a bit expensive.

Why buy, when you can build?

So I built a jig for cutting the v-groove and and it’s turned out pretty good.

The inside angle of is 40 degree, so the jig hold the material at 110 degree relative to the table, giving the required 20 degrees on either side.

Operation is just like cutting a circle on the tablesaw, but with a different angle.

When I attach the pulley to the shaft, note that I’ve drilled and tapped a hole. I have a 1″ 1/4-20 screw on either side. One of them is visible and the other is hidden.

I’ve been wanting to do some metal casting ever since I came across thisseries of books which teaches how to build ones own metalworking machinery. Metalworking is not something I’ve tried before and I don’t really have a need for it (yet, perhaps), but the projects seem cool.

In order to build said machinery, you have to first learn how to cast metal and there’s actually a fair amount of interest in this one out there. My favorite link isthis one andthis page in particular.

So I got some old broken down lawnmowers from a friend who was moving out of her house and I got an old toyota tranmission from someone off craigslist. Thankfully, I’ve got my big rocket stove to get the larger pieces hot enough to break them into more manageable bits.

Aluminum melts at 1220 degrees fahrenheit. That seems pretty hot, but it’s actually not. If you take a wood fire and blow air on it, you can reach that. If it sounds like an airplane is about to take off, you’re in good shape.

My furnace is made out of an old piece of wood stove venting.

The inner space was filled with a simple mix of concrete, fireclay, sand, and perlite. I filled the outer space with just perlite to act as insulation.

What do I use for fuel? Used motor oil of course. I had some "laying around" from the last couple times I changed the oil in my truck. The link above as well as this one prompted me to try it.

As always, click the pictures below for larger images.

The basic idea is to blow air into whatever it is you’re burning. In my case, I start with some charcoal, maybe 10 or 15 pieces. If you look closely at the picture on the right, you’ll notice a length of 1/4" copper tubing sticking out both ends. The two bolts you see and one that you don’t hold the tubing centered. The left end is connected to some plastic tubing, through a valve to the kitty litter bucket on the chopping rounds. To connect to the kitty litter bucket, I simple drilled a hold a little smaller than the 3/8" nipple (I wrote nipple, huh huh)

Also notice the small fireplace rack looking thing in the upper right corner of the picture on the right. That’s to give the flame some room to combust. It’s just rebar bent and welded.

To lift the "crucible" (AKA the 5" tubing) I used pliers. While this works, I need to rig up a better way to maneuver the thing.

Here’s setup again fully assembled. This one has the valve I used at first. The adjustment is very sensitive. I quickly go from not much action to full liftoff. I now have a metal ball valve. still very sensitive, but less sticky.

Also, note the first ingots.

Here are some shot of the foundry running.

It’s been a while since my last posting, but I have been working on my rocket stove and I’d say it’s just about done. My first stove was pretty small, measuring 6″ in diamater inside and 10″ outside. Well, the new one is made from a 55 gallon drum.

One of the big lessons from the other stove is that airflow is key. I recently had the furnace in my house replaced and I had the guys leave the old one behing so I could scavenge for parts. One of these parts is a blower fan.

Next, I needed a way to distribute the air into the combustion chamber (how’s that for technical jargon?) If you look closely or click on the image for a larger view, you’ll see that I’ve drilled holes on one side of each of the tubes. This is also to cause a swirling. I want the air to move around as much as possible before leaving.

Here are some shots of the barrel from below. This should give you a better idea of what’s going on.

next

And here’re a couple inside shots.

Next, I created some forms so I could line the inside with a cement, sand, perlite mix. The perlite is to make it a bit insulating.

Instead of removing the forms, I just burned them out.

Here are some shots of the stove in action.

A last optimization on the stove is a lid. I haven’t tried it yet, but I think it will help it burn even better.

Stove performance

So far, I’ve been very pleased with how the stove operates. I’ve been able to burn sawdust, woodchips, firewood and construction scraps. The main issue is with the sawdust. The problem there is that as the upper layers of sawdust turn to ash, it seals away the unburned sawdust. The fire dies down a bit and then when I stir it a bit, it fires back up. Figuring out a way to make it into blocks would be neccessary to really make it work with that kind of fuel.

Wood and woodchips burn pretty good though. I’m looking forward to seeing how the lid does.

As always, click for larger images.

I’ve been wanting to put in some rainbarrels for a while now. Dan, a friend of ours from Robie’s job, has rain water collection at his house and I’ve thought of it ever since. Dan has two 275 gallon liquid “Totes” but I opted for regular 55 gallon barrels because they fit under the deck/porch.

First I build some racks to hold and stabilize the barrels. As you can see in the pictures, I made a simple tramel for my jigsaw. It required a bit of adjustment for blade drift. What this means is the the blade of the saw has a certain direction it wants to go and after a while of following a certain trajectory, the blade will curve to the left or right. I”m not talking about the curve of the cut, but a curve in the blade itself. To compensate, I rotated the saw a little bit in the same direction of the blade curve and the blade stayed vertical.

Note that Frankie was very helpful.

To connect to the downspouts, I used 2″ ABS (drain) pipes.

Because it’s inevitable, the crud comes down the gutters along with the water, I put in some features similar to a septic tank.

First, I extented the downspout well into the barrel. I epoxied a 1.5″ length of ABS inside the 2″ I was using. It extends to about 8″ from the bottom.

Second, for the exit, I make the water level be a little higher than the exit point. The overall exit is higher than the end of the 1.5″ pipe.

What this means is that water and crud are delivered directly to the bottom of the barrel and the crud will either sink or float. If it floats, I don’t want it to be channeled directly to the water exit and that’s why the corner is there.

That’s an awful explanation, but hopefully the pics help clear it up.

Here are some of the barrels before I dragged them under the porch.

Today is Jovan’s birthday so we went out last night to celebrate. A fun time was had. I’ve got a boatload more pics on my website. 25 years. getting old.