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Arduino Project – Temp / Humidity

In preparation for my first “real” arduino project — a bathroom lights/vent fan controller using humidity and motion sensors — I’ve whipped up this temporary rig:



Inside the box there’s an Arduino Nano, 16×2 LCD and some glue components.  5V comes in from the black wire on the right.  Sticking out the top-left (short wires) there’s a WiFi module and the at the end of the longer wire are two temperature / humidity sensors (blue and white thingies).

The goal of this thing is to capture some data about how the humidity changes in a bathroom.  I want to figure out whether the cheaper blue sensor is worth using (spoiler: it’s not), when to turn on the bathroom vent fan and later turn it off, and in general I’m just curious about stuff like how much difference does the fan make, etc.

The rig takes a sensor reading every few seconds and sends it over WiFi to my computer.  For a quick test I ran it for a bit this morning, then I dangled the sensors inside that water bottle on the right for awhile, waited for things to stabilize and took it back out again.  The test ran for an hour:


Here are the results: solid lines are temperatures (degrees Celsius on the left Y axis) while dotted lines are relative humidity (%, right Y axis).  Green lines from the white sensor (a.k.a. the good one) and red lines from the blue sensor (a.k.a. the crap one).  At 08h14 I moved the sensors into the bottle and took them out again at 08h45.

The first thing I learn from this is that the cheaper blue DHT11 sensor (plotted in red) is terrible.  Within 20 seconds the good one jumps to 80% RH while the crap one takes 3 minutes to rise up 20% from 35% to 55% RH and takes more than 15 minutes to approach a stable value while the good one reaches stability within a minute.  Both return to baseline more quickly after being removed but again the crap one takes longer.  Interesting that it comes down much faster than it goes up.

The crap one’s precision is +/- 1 degree while the good one is tenths, in case you were wondering why the temperature from the red sensor looks wacky.  Both show a slight temperature increase right after being exposed to the high humidity chamber and both show a slight temperature decrease after coming back out (although this is harder to see with only 1 degree precision on the crappy one).

The DHT11 (crappy blue sensor) costs around $1.50 on eBay free shipping from China while the DHT22 (good one) is around $4.50.  The Arduino Nano board is around $3.25, the WiFi module is around $3.50.  Because the WiFi module runs on 3.3V and will die if it gets the 5V that the Nano runs on, I needed a logic level converter ($1.50) and I used freecycled diodes to drop the 5V supply voltage to around 3.3V.

2002 Toyota Corolla CE

Manual transmission (manual everything!)

175k kms on the odometer




Extra stuff:

  • Clarion stereo w/ CD & 3.5mm AUX input for your music player
  • Upgraded speakers, external amp. and trunk sub-woofer
  • Auto-start, because winter sucks
  • All-season tires on non-rusty aluminum alloy rims (winter tires on original rims are on the car)
  • “Hidden Hitch” tow package (ball and bar included)

Extra words:

If you want a shiny brand new car in great condition with all the bells and whistles look elsewhere.  This baby features old-school windows that you roll down with your muscles.  If you want the door unlocked you pull a mechanical lever, no fancy buttons or remotes with this classy beast.  Power steering and power brakes, yes, but none of that fancy anti-lock brake stuff or traction control.

She is 14 years old and has spent all that time on Ottawa roads, so yeah, there are some rust spots.  If you want a shiny brand new car in great condition with all the bells and whistles look elsewhere.

If you want a cheap car that runs well and saves you gas money, come see this one.  Corollas are well known for being tough little beasts that need little.  That said she has been well cared for with regular maintenance.

She has great fuel economy: I usually get 550km before I fill up.  She has a 50L tank but I fill at 1/4 or so, say 35L fill-up, so that’s around 6 L/100km.  On a trip to Windsor I went over 700km on a tank.




Why I sell?

I am from the “own the car and drive it ’til it’s dead, Jim” camp.  That said, I like trailer camping and the camper I have needs a bigger beast to tow it, so I went and got a truck.  Now I have a Corolla in the driveway taking up space and insurance money.  It needs a home.

Clay Cross Car Crisis

Here’s a story from when the family and I visited the UK earlier this year:

Visited the UK in July, took a rental car from London to a cottage we rented in Ashover, Derbyshire. Rained hard on the way there.

Evening came, we needed supplies. Google told me about a Tesco in nearby Clay Cross. Got in the car. Brought eldest daughter (3) with me. Bam, windscreen immediately misted up. Warm rainy day, cool rainy evening, all that humidity everywhere.

Turned on A/C, that defrosted the inside but caused a pile of condensation on the outside. Wipers took care of that. Headed for Clay Cross.

Inside started misting up again. Buzzed the windows down, tried the heater instead, that made it worse, switched back to A/C on high.

That kept things clear, but I had to do the whole trip that way. Close the windows, turn off A/C, or stop the wipers: any of these resulted in windscreen misting up.

On top of all this, Google Maps wasn’t quite clued in about Clay Cross and tried to make me drive the wrong way down a one-way bus pull-in. A kind lady warned me. She called me “duck”. As in, “Ya can’t go that way, duck, it’s for buses. You’d best turn around, quick.”

Turned around, drove away taking left turns until Google reticulated splines recalculated route and got me there in a more legal fashion.

TL;DR LHS driver in RHS car, first day in a new town, fighting mad humidity inside and out, after dusk with bad sat-nav directions. Windows down, A/C blasting, wipers going, rear defrost on. My daughter learned some new curses.

For all you salt lovers

If you want to decrease your salt intake and increase your salt enjoyment, or if your loved ones badger you about how much salt you eat, read on!

Powdered vs. Regular Salt

Powdered vs. regular table salt

Taste is your reaction to chemicals on your tongue. More surface area means a faster reaction which means a more intense burst of flavour. SCIENCE!

Here’s a silly diagram:

Flavour increases with surface area

Flavour increases with surface area

My opening photo is a macro shot of regular Windsor brand iodized table salt on the right, and the same salt finely powdered on the left. How do you accomplish this?

Etchd glass mortar and pestle

Etched glass mortar and pestle

Any mortar and pestle should work. Mine looks like this, a glass one with chemically etched grinding surfaces. Just add elbow grease until it looks, feels and acts like white all-purpose flour.


Using salt this way results in a more intense flavour but it also results in using a lot less salt, and not just because you don’t need as much to achieve that yummy salty taste. Since it’s a fine powder, there’s lots more airspace between particles. A third of a shaker of regular salt makes a full shaker of powdered salt. As well, when you dispense it on your food it looks like you’ve put lots on when you really haven’t. Your built-in “that looks like enough” instinct actually results in lots less than you’d get with more coarsely ground regular table salt — yet the yummy salty taste is stronger and your shaker stays full longer.


A final note: don’t add your salt when you cook; sprinkle it on just before you eat. First of all, not everybody likes the salt so anyone sharing your meal will appreciate your light-handedness. More importantly, though, you want to make good use of every little bit of salt that goes into your body. A lot of salt dispersed throughout your food has nowhere near the concentration that just a little bit on the surface does, so don’t waste your daily allocation of sodium; put that powdered good stuff right on the top where it will have the most impact.

(even for something like a broccoli cheese soup where the salt dissolves, it will stay near the surface since osmosis takes time)

Cucumber slices sprinkled with powdered salt

Cucumber slices sprinkled with powdered salt

When I nom these delicious cucumber slices I flip ‘em on the way in so the salty side hits my tongue first.


At home I keep my powdered salt in a shot glass. At my office I just have a regular old salt shaker — if you tap the bottom of it, it sounds hollow! A sign that I have ground it finely enough. Flour sounds the same if you put it in a shaker (we keep a shaker of flour at home to easily sprinkle our rolling surface).

Powdered salt is more susceptible to caking than regular table salt. It’s not as “free running”. If you keep it in a shaker you can just tap the side against your table a couple of times and it will come good right away. If you keep it in a shot glass or bowl you’ll want a salt spoon.

Homemade Salt Spoon

Homemade Salt Spoon

I’m too cheap to buy a proper fancy salt spoon so I made this one for my office. It’s the underside of a fork, with the main body and tines ground off on a bench grinder, the edges filed and polished up. This particular fork is made of stainless Japan. I didn’t know Japanese were stainless?!

Use your salt spoon for stirring your powdered salt and also as a classy way to sprinkle the delicious powder onto your food. Be sure to raise your pinky finger and adjust your monocle as you lightly tap the side at a medium pace from a respectable height, wot?


Your body needs a small amount of salt to operate properly. Unless you have an unusual diet your everyday food already has enough in without you having to ever add any at all. Your loved ones are right: you could and probably should just give it up entirely. That way you can live to be two hundred years old without ever enjoying another meal. (I joke, I joke!)

They say that diet drinks like Coze Zero aren’t good for you because even though you aren’t getting sugar from them you’re still satisfying your sugar craving which empowers that craving, which means that you take more sugar overall to keep yourself satisfied. If my technique means less salt but more salt taste then maybe you will end up empowering your salt craving and take more salt overall, so be a mature and responsible adult.

Be aware of this trap, use this new tool I have given you wisely and promise to use this new power to drastically lower your salt intake and live a longer and healthier life. All things in moderation.

This is the part of the article you share with your loved ones to keep them from getting mad at you. Or worse, ME!

This article is not sponsored in any way by Windsor salt or the Canadian Salt Company or Salty Salt Salt Traders, Inc. or anyone else. If you want to be a sponsor please send me a giant salt lick like what livestock have on farms. I have always wanted to have one in my living room that I can just walk up and lick whenever I want, just like a cow.


Evening Ritual

I stand before the door to the basement. The main floor is reasonably cool and dry, considering our aging air conditioner has been struggling all day.

The basement is colder, naturally, but there is when I open the door a pocket of warm, humid air that neither realm can claim. Strange.

Artemis and Psyche impatiently remind me of the business at hand.

The cats are hungry.

I turn around and slide the lock on the cat door. Into the basement, then a handful of cat food for Artemis tossed in his dish and not a second passes before he’s into his evening meal.

Upstairs I bend down and awkwardly pour the other handful into Psyche’s dinner bowl, strategically placed where it’s hard (for humans) to reach so she can eat in peace from the rambunctious young child.

She dunks her head in there to start scarfing down before I even finish pouring and ends up taking a dry food shower behind the ears.

The time it takes Psyche to finish could be measured in wavelengths of cesium, and then she’s lurking by the basement door.

She can’t get past the cat door but she knows that Artemis is down there and he hasn’t finished his food yet. There is only one place to wait.

The minute hand sweeps a leisurely radian and I hear the sound of Artemis at the cat door. The second hand traces the same path and then he’s defeated the sliding lock.

His evening meal finished, the lord hath come to keep watch over his domain. He suffers the humans to live in this place, but they bear watching.

Meanwhile, the cat door hasn’t finished swinging ‘fore Psyche has dashed downstairs to see if Artemis left anything unfinished.

23 hours and two pi minus one rad minutes later, then repeat.

Got Stir Sticks?

Take a couple of extra paint stir sticks …
… you never know when they’ll come in handy.

The Painnier

Do you loathe loaves crushed in panniers?
Relieve that pain (haha) today with a Painnier!


This is just a cardboard box I crafted to protect a loaf of bread, because we all know what happens if you try to squish a loaf into your pannier.

Here’s what my bicycle looked like for this morning’s commute:


I had to stop mid-ride and waste several minutes adjusting this monstrosity so it didn’t spill my groceries across Greenbank. This problem needed a solution.


(*) Double-walled including alternated corrugation “grain” for strength++;

(*) Angled braces at the vertices for rigidity++;

(*) A layer of packing tape for water-resistance++;

(*) Duct tape carry handle for portability++;

(*) Strap down points on the bottom — just like the carry handle only smaller, flatter, and there are two of them that line up with the straps already on my bike to hold my laptop bag.


(*) A strap to keep the last end-flap closed. I have a plan for this involving duct tape and coat hanger wire.



I hope my new minimalist shoes (see previous post) will reduce the need for this thing, but I made it it today and wanted to show it off somewhere.

The short version: it’s a shoe dryer! The two fans fit perfectly into the right side of the … cardboard duct contraption. The two tubes on the left go into shoes. Air blasts through the ducts and dries the shoes.



The fan assembly isn’t new. I made it because temperature regulation in my office is a fiasco. In the winter my space gets really warm — 28 °C occurs several times a week — while the rest of the space varies wildly.

(on some days the number of people walking by to adjust the thermostat at different times is practically a parade)

I built the fan to fight those heat spikes. I also do exercises in the morning and it’s nice to cool off quickly after.

It was just the bottom fan for the first version but that was just barely adequate and I wanted more so I lashed a second one on there to make the beast you see.

Here’s a picture from a desperate day in late November when I put a cup full of ice-water behind it.


Since I spend much of my day delivering presentations by phone it’s important that my desk fan run quietly. I power these 12V fans from a 9V power supply which balances plenty of airflow with very low noise.


When it comes to shoe drying, however, more airflow is better and never mind the noise, so I use a 12V power supply. The cardboard duct contraption adds to the noise so it basically sounds like a small vacuum when it’s running.


All of this stuff is re-used. The fans come from old computers, as do the brackets supporting the fans at the perfect angle — they’re slot covers. The top fan is lashed to the bottom using old wire. The screws holding the wire and the brackets are the ones that originally held the fans. Even the wiring and plugs are re-used.

Both the quiet 9V desk- and screaming 12V shoe- power supplies are re-used wall warts who lost their original poweree in the war on dead office equipment.

The cardboard shoe-dryer duct is from an old box; the tubes are from a paper towel roll hewn in two. Not a flimsy one like you get at home — our office bathrooms have thick, industrial strength paper towel rolls.


The 12V power supply I use is rated for 2A. The two fans use about 0.5A together. I’d like to make a heating element to go inside the duct. (what fire hazard? no see fire hazard!) A couple of big power resistors, maybe? I have a USB coffee cup warmer (which almost completely fails to warm coffee) and when I took it apart, that was all that’s inside — a big power resistor stuck with thermal paste to the warming plate.


These three things happened:

  1. The only shoes I have — steel toed winter boots — are about dead with busted seams;
  2. My sister sent me a Sears gift card for my birthday; (thanks sis!)
  3. I found these “Body Glove 3T Barefoot” shoes on Sears’ site for exactly the right amount.

Clicky clicky, waity waity and then I have shoes from the internet! YAY! No more mostly dead winter boots!

What I like:

Biking in rain

These are designed for water — kayaking, surfboarding, swimming near rocky shores, etc. The soles have mesh-covered drain holes. The metal mesh protects from pokey things stabbing into your foot but allows water to escape. More importantly, less material compared to other shoes plus vent holes equals faster drying time.

I’ve already soaked my other shoes twice this month from riding in the rain, so I’m especially appreciative.

(In case you’re wondering, you can put soaked boots over an air vent when you get home from work and they will be dry by next morning, IF your fan runs 24/7)

3 Toes

The “3 toes” is a double entendre as there are 3 toe compartments: big toe, next toe over, and smallest 3 toes in one.

I haven’t tried the 5 toe variety of minimalist shoe, but one supposed advantage is that these are easier to put on. I believe it. I have accidentally put 4 toes in the 3 toe area a couple of times. You learn how to slide these on so that big-toe and next-toe-over slide into the right slots. I imagine that’s more tricky with the 5 toe ones (though I’m sure 5T fans have it down pat also).

Closer to barefoot

They don’t call these “minimalist shoes” for nothing. We humans evolved to walk on feet, not in shoes. People adapt to shoes well, but protecting your feet with conventional shoes costs some agility (balance, terrain grip). Usually not a problem, so you don’t miss what you don’t really need. The idea behind minimalist shoes is to recover some of that monkey-style agility while still protecting your feet.

While 3 toes isn’t quite 5 toes, it is (supposedly, yet I believe) easier to put these on and your three smallest toes don’t operate as independently as your biggest two do, so it’s a fair compromise.

Sock option!

I wasn’t planning to write a review or anything at all until I discovered this just today: you can wear socks with these!

To me this is a huge win.


I experienced an example of the agility win yesterday while mowing the lawn. My yard has a hill which is pretty steep in places. It’s a pain to operate a lawn mower across it for various reasons, one of which is keeping your grip and balance while wrangling a lawn mower across the slope.

(On the down-side, the holes on the bottom get clogged with cut grass, but once the shoes and grass bits are dry the crud disappears pretty easily)


A big downfall of wearing any shoe directly against your foot is that the sole of the shoe itself (a) wears out much more quickly; and (b) gets smelly faster. If only there were a layer between foot and shoe that you could remove and wash separately and much more often.

Before I discovered these shoes work with socks I was planning to get slippers for my office. You can imagine what wearing shoes like this for 8 hours might end up like, especially your ride to work damp.

With 5 toe shoes this isn’t an option unless (a) you have toe socks (I don’t); and (b) they fit in your shoes. I imagine that a 5 toe shoe which fits you nicely without socks won’t fit well even if you do own toe socks.

Recall where I noted above that I managed to put 4 toes in the 3 toe area accidentally a couple of times. With socks, you just karate chop a divot between your big toe and the others, and take advantage of that happy accident.

This opens the door to wearing this kind of shoe for long periods of time without worrying about stinkification. WIN!

I love it when I can solve a “this thing is great, if only this one little detail” type problem.

Here is my 2013 CN Cycle for CHEO trip log:

07h20 / 0.00 km — Left home to ride to CN Cycle start.

07h29 / 2.96 km — Felt repetitive bumping from the rear. Pulled over to investigate:


If you look closely at my rear tire, you might notice it’s a little out of whack:


You can see where the rubber has ripped away, exposing structural weave underneath. I drew some red lines to help demonstrate how the whole tire has gotten misaligned.

At this point I let some air out of the tire and turned back home in disappointment.

07h35 / 4.25 km — BANG! Rear tire asploderates. Start walking.

07h58 / 5.90 km — Home again.


That white spot on my rear tire is the shredded remains of the cloth that’s supposed to be underneath a layer of rubber, blown outwards when the tube inside exploded.

On the plus side, at least it became apparent early on. It really would have sucked if it had failed while I was downtown. Or if it had asploderated without my noticing first, making me walk several km home instead of just 1.5.

EDIT: Later that day…

For me, the day was still pretty awesome. I spent the day with my daughter, we went shopping and got a new tire and tube and some supplies to have a barbeque. A bunch of friends came over, we fired up the grill and enjoyed the weather in the back yard. Even had enough time left in the day to get the new tube and tire installed so I could ride to work on Monday. No worries.

The really great news is that this year was an EPIC YEAR for team US. Together we raised $741 bucks, which is FANTASTIC! Overall the event total was $726,410. Go ahead, feel proud. You earned it.

You may have noticed that I didn’t send out a follow-up email this year whinging at you (no, not YOU) for procrastinating. That’s because this year’s response was so AWESOME!

Unfortunately that means this year sets the bar for the future, so if you could all just set a side a little tray by the front door for your spare change to save up for next year’s CN Cycle for CHEO, that’d be great, m’kay?

All joking aside, thanks again to everybody who helped out this year. Look at what we did. Just look at it. Would you look at it? Wow.

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