Servos!!

I just received my servos! I can't wait to try them out!

Shower head awesomeness!!

Kerry and I take showers together. Only one of us can be fully in the stream of water from the shower head, while the other endures coldness! First-world problems, I know. But no longer!!!!! Today I bought two shower heads and $15 worth of pipe and installed an additional shower head!!

I knew it would be novel, but I didn't expect it to feel like we were in a luxury resort. It's so incredible! The shower heads were a little pricey because I wanted "rain" ones, but the pipe was super cheap PVC! I'm sharing this because I'm really really happy about it.

Arduino + temp sensor!

I took another step toward actually building this, which was to start using the temperature sensor and the arduino! You can see in the picture below that the sensor is sticking out of the arduino. It's super easy to use - just plug the outer two pins into 5V and Ground, and the middle pin into an analog input. 

Arduino sitting on my bed because I have no desk.

Then I downloaded some simple code from adafruit.com, from which I bought the sensor. If you don't know who Ladyada (Limor Fried) is, you should read about her. She was instrumental in bringing about the arduino revolution, which put easy-to-use microcontrollers and electronics within reach of non-engineers like me and allowed millions of people to make LEDs blink.

As you can see, it's reading the temperature! Super awesome! Now I need to embed the sensor in a coupler that will go between my shower head and the pipe coming from the wall. Annoyingly, Home Depot doesn't have something as basic as a 1/2-inch coupler, nor a 1/2-inch splitter (I have plans to put in an additional shower head that runs to the other side of the shower so Kerry and I can each have water!). Looks like I should have just gone to Orchard Supply yet again, because they have like every kind of pipe you could want.

Now I just need to get my servos!! The Hong Kong mail doesn't have the same level of tracking that we do. All they can tell me is that the package left Hong Kong about a week ago. Hopefully it'll come soon!!

Waiting for servos

I've been wondering where my servos are because I'm excited to get going! It turns out that they've been in the process of getting to the Hong Kong post office. But I'm happy to know that they officially shipped today. In the meantime, I have an idea of how to logistically control the temperature.

To start the shower, the hot knob will be turned up all the way. As it gets hotter, the cold will be turned up to compensate. If hot water starts to run out, cold will be reduced until it's all the way off. In a situation where the cold water in the pipes isn't very cold, it will turn up all the way. If the temperature is still too hot, the hot water will be turned down until it's all the way off. Once one of the knobs is all the way off and the water isn't the right temperature, it will make some kind of signal. Here's a graphic that I made!

So lots of great ideas. I just have to stay strong once the parts arrive this week and I actually start to build this thing and run into problems!

Servos after all

I thought I'd found a good solution, but it looks like the cheap gearmotors I'd found have a clutch that limits torque to about 60 oz-in, which is almost half what I need. So instead I kept looking and discovered ServoDatabase.com, which appears to have every servo on the market! I narrowed down the list to servos with over 100 oz-in of torque. I've actually found what look like some great deals. After narrowing it down to five of them, I've decided to go with the TowerPro MG945.

It's got 166 oz-in of torque, metal gears, and costs $8.99!!! Unless it turns out to be a piece of crap, this is going to be awesome. Including tax and shipping, two of them cost $26. An arduino knockoff costs about $30, so the total so far is $56. I still need some kind of housing, seeing as it's gonna be in the shower. I also need something a coupler to put the temp sensor in, and something to hold the servos steady. Thank goodness this is a prototype! They always cost more than what people end up actually buying. I've just been trying to do it cheaply so I can build them for friends.

Well, now I can get started actually making the thing work. I should be able to read the temperature myself, but I'll need help making the servos compensate for temperature changes. I'm really excited. I don't even care that someone else may have done it (although a quick Google search didn't find anything), because I just want to actually build something fully. We'll see how I feel once the parts come and I actually start putting everything together, but I'm very hopeful. Yay!

Less expensive motors?

Two posts ago, I had found a servo that exceeded the torque I need. However, it costs $31. I'll need two (one for each shower knob), which will bring the price too high for a novelty-buy. So I've been looking for alternatives. My first thought was gears, which can increase the torque to essentially any amount. Adding gears and buying a cheaper motor should drop the price significantly, I thought.

Annoyingly, gears are really expensive! I found one for $3.60, but in order to increase the torque, the cheapest complimentary gear I could find was like $14! So almost $18 worth of gears, and I still need a motor. And I don't actually know how to set gears in place. While I may still be able to get help from people who know how to use gears, I think I've found an alternate solution: a cheapy gearmotor!

These gearmotors cost about $6 each, and can be retrofitted with a $2 motor to double the torque, which would bring it to about 100 oz-in, which is what I need! Look here for more info. Ok, gots to go to work :(

Temperature sensor!!

My TMP36 analog temperature sensor has arrived! It cost $2 and can measure from well below freezing to well above boiling with 1/10 degree accuracy! You just plug it into an analog input in your arduino and it's awesome. This is a great component.

Also, I mentioned this project to my friends Aaron and Brad, both of whom are engineers. They both got really excited and offered to help, which felt really good. Aaron actually has a degree or something in electrical engineering, which is awesome. I'm hoping to learn how to use gears instead of expensive servos to turn my shower knobs, and he may be able to help. Yay!

Gathering Information

While my plan involves several stages, I'm doing some extra work at the beginning to gather information about all the stages. This will allow me to save time later, because if it's not going to work to turn my shower knobs with servos, I'd like to know before I order servos and hook them up to my knobs.

I first started with a temperature sensor. I chose the TMP36 from Adafruit, which is an analog sensor that costs $2 and measures from -50C to 125C with 1/10 degree precision! Awesome. Wonderfully, it comes with all the code and instructions you'll need in order to use it with an Arduino. I consider this to be feasible.

Next, I'm gathering information about the servos. This document describes in a general way how to size a servo motor to your application. Brush or brushless motor? This site seems awesome, and it tells me useful stuff about servo motors! Ok, so I think I'd actually prefer a stepper motor, and once again Adafruit has one that might work. But how do I know? The motor is rated for 28 oz-in of torque. Will that be enough to twist my shower knobs? Let's find out...

I've got a little scale that measures up to 24 oz. The knob on the shower is a cross with arms about an inch long. So if I press the scale against one of the arms and it turns with 24 oz or less, that means the motor should work!

After testing, the answer is... nope. Rats. Next, I've found an awesome video describing the characteristics and differences between steppers and servos! It sounds like a servo is what I want, because they are designed to operate within a single rotation. I tested my shower knobs, and I only need to go between 0-180 degrees, so a servo should work great! They also are much easier to operate than steppers because you don't need a stepper driver, and you can just hook them directly up to an Arduino. Ok, so I'm looking for a servo after all.

I found one servo that's rated for 70 oz-in. That seemed like a lot, but I wanted to be sure. So I had an idea! I'd tie a ruler to my shower knob and push it with my little scale. Then I'd multiply the distance from the pivot point by the number of ounces of pressure on the scale needed to move the knob. So I did it! Unfortunately, twisting the knob from the off position took about 100 oz-in, and moving it while on took about 70. So it looks like I'll need a pretty strong servo. They're often rated in kg-cm, so I need one that's about 7 kg-cm. Hopefully it'll be less than $30.

I've found one rated for a whopping 24 kg-cm, but it's $79. I found a few others that either were too expensive or too cheaply made or otherwise questionable. Finally, I found this one for $31, which is acceptable but still a little too expensive if I want to sell this idea as a product. I'll need two of them, and with the addition of the Arduino it'll cost over $80 in parts. I may just go with this to save time, but I'd ultimately like to use an inexpensive motor but with additional gears, which would provide the same torque at a much lower cost. If I could get the total cost close to $20, I think I'd have a product that at least a few people would buy. I remember Kelsey saying she wanted one at the party last night.

Stay tuned!

Owen the Inventor

All my life I've known what I wanted to be: an inventor. But I've wanted it so desperately, and been so afraid that I couldn't have it, that I've created a funny kind of ambivalence over the years. I would get excited and start pursuing an idea, only to abandon it and stop all activity for months when I ran into an obstacle. In my earlier years, this didn't bother me too much because I was young, and I was sure I'd figure everything out sometime later. Now I'm 27 and still working in a field other than inventing, and I'm enjoying it less and less every day. It's very clear to me that unless I do something in a consistent, intentional way, there's no way my life is magically going to change course.

So what do I have? I never went to engineering school, product design school, or business school. I don't have much spare cash to pay for engineers, designers, or business people, although I do have a little. I have a degree in film, lots of experience in IT and the SF corporate video industry, and lots of ideas. I have a good amount of experience in construction and building things, and have very basic experience with soldering circuits. I also have a wonderful girlfriend, Kerry, who loves me and wants me to be the best I can be, and I have a number of friends and acquaintances in various fields that could help me on my quest.

What do I want? I ultimately want to have a team of intelligent and talented designers and engineers who create awesome products. I want a "bat cave" like Bruce Wayne where the sky is the limit as far as what can be created. And I want to make things that allow people to be happier, feel better, enjoy life more, and experience less frustration and discomfort. I want more love, connection, happiness, and abundance for myself and for the world. And I want to make a ton of money.

What am I going to do right now? I'm going to start from square one and make a consistent effort to progress. I have a bunch of ideas, from perforated hamburger wrappers to traffic jam drones to vibrating smoothie pitchers, but as long as they remain as ideas, they're worthless. To move forward, I need to actually make something, but it needs to be both interesting enough to be worth doing and simple enough to do myself or with limited help. No modeling in SolidWorks, calculating fluid dynamics, or getting UL certified. After unhappily putting the vibrating pitcher on hold because of those very issues, I arrived at an idea I think I can do: an automatic shower controller.

I live in a house with several people, and when I take a shower, I always run the risk of getting doused with cold or hot water if someone turns on a sink or another shower. When that happens, I have to frantically mess with the hot and cold knobs until I can get the temperature back to what I want. Then when they turn off the sink, I have to do it again. Sometimes it happens several times in a row. Not a world-ending phenomenon, but something that would be great to take on as an inventor. I'm pretty sure I can do this with an Arduino, a temperature sensor, and some servo motors.

Now, to avoid taking on too much at once, I'm breaking this into several parts. The first part will just be to sense the temperature of the water. Pretty simple. I've already got an Arduino and my $2 sensor is coming in the mail any day now. I'll get a coupler to fit between the pipe and the shower head, and I'll embed the sensor into it.

I've also started reading inventor blogs! One of the first things I read was to do a lot of work in the early stages to determine how feasible your idea is - before you invest a lot of time and money. I made the mistake of not doing this with the last idea I tried to build. My dad and I invested a couple thousand dollars into patents, only to realize once I started testing it that my idea wasn't going to work. That sucked. I'm not going to make that mistake this time. However, that means that I have to find out if I can use servos to twist my shower knobs. I'll report back once I have some kind of answer.