I can't believe it's been over a year since I first mentioned my sous vide project! Ugh; I'm so discouraged.
I actually have made some progress on this project. In the past year I've prototyped the circuit, I've written the software, and verified that it does, in fact, work. I haven't documented any of that on my blog, though. I've been wanting to do some tutorial-style posts on this project and have drafted three or four posts in the series but I need to get in the workshop and take some pictures to go along with those posts, and the workshop has been a mess. (There's progress on that front, too, but that's a separate post.)
Yesterday, I ordered parts from Mouser for my sous vide controller. I'll lay out a circuit board with those parts and order boards, then build a real, actual board. Hopefully that'll take less than a year!
As I've mentioned here before, I'm the father of two young boys. Today, they're 3 and 4 years old, so not quite old enough to participate in making/hacking.
But that's going to change in a hurry. In fact, just yesterday my older son asked me to help him build some birdhouses. Now, I don't know why my son wants to build birdhouses (I'm assuming he saw it in one of the children's shows he watches), but you'd better believe that my son and I are going to build birdhouses together. And soon.
My dad always had a garage full of tools. He didn't often do much with them, but they were there. And he taught me how to use them. I worked mainly with wood, but as far back as I can remember, I was always confident that if I wanted something that could be made of wood, dad and I could make it.
I've done some reading recently that makes me think that this is not typical in today's era. I read in Make magazine today that a college professor teaching a freshman level engineering class this year asked how many of his students had ever used a drill press. Nobody raised their hands.
Nobody.
That absolutely shocks me! I can't imagine not knowing how to use a drill press. And I can't imagine raising my sons to not know how to use a drill press.
Though dad had plenty of woodworking tools, that was about the only medium that I felt comfortable working with. My father-in-law is planning on building himself a "Bucket T" car. As a teenager, if you'd talked to me about building a car, I would have thought that you needed a car factory to build a car. You know, only Ford or Chrysler or GM can do that kind of thing.
One of the burning desires I have is that I want my kids to grow up believing that they can make anything. I don't want their imaginations or ambitions to be crippled by thinking that something can't be done. And that is a large part of why I'm finally going to build the workshop I promised myself this time last year. (It's not the only reason, but it's an important one.)
Then I'm going to have to stock it with tools. I have some basic woodworking tools. I have a stick welder. I'll need to add a lathe/mill and learn to use them so that I can teach my kids. I'll have to pick up fiberglass skills somewhere. I'm going to have to build that CNC router I keep dreaming about. And of course add a 3D printer and a laser cutter.
When my son is 14 and comes to me with a great idea of building a go-cart with a lawn mower engine, my son and I are going to be able to head out to the garage and build one. He's not going to be left with a dream and no opportunity to realize it. We may fail in building the go-cart, but we'll have fun trying, and we'll learn something in the process.
He's going to go to high school one day (or maybe even junior high) and show off the Stirling engine that he built on dad's lathe. When the physics teacher assigns a group project to his class to build some contraption, his project group is going to meet at our house, because his dad has the workshop and the tools needed to build the best contraption in the physics class competition.
That's what I want to provide to my children. And that's why I need a garage workshop.
I've been pretty lax in updating my blog lately. Part of that is that I haven't had a whole lot of time to tinker in the workshop. Let me give an outline of some of the projects on my plate right now.
First, I want to finish my sous vide cooking controller. I've developed the schematic and am in the process of selecting parts. Then I'll lay out the PCB and either etch one myself or get one fabbed. With the low prices offered by Seeed Studios and iTead, I may opt to get a board fabbed. I want to design this with mostly SMT parts. The industry is headed that way and most of the newer and cooler chips are only available in SMT packages. I might as well jump on the bandwagon now. There will be some through-hole parts on this project; notably the power transformer, the LCD display, and the TRIAC. Maybe some others as well. We'll see what it looks like when parts selection is finished but it's going to be mostly SMT with some through hole stuff in there.
Second, I'm building a combination-lock solving robot. I have this combination lock on my desk to which I've forgotten the combination. Rather than doing what a normal person would do (throw it out and buy a replacement lock for $6), I'm designing a rig with an Arduino and a setpper motor to try all possible combinations until the right one is found. I bought most of the parts with my Free Day coupon from Sparkfun. The code is written and the motor turns as expected, I now have to build the physical structure to hold the lock, mount the motor over the lock's shaft, and pull on the shackle. There are other projects that have done this before, but I enjoy the process of making so I'm going to build one myself.
Third, I've been inspired by a project by Markus Gritsch. He built a digital music box that plays beautiful, music-box-like sounds from a PIC32 and no analog parts whatsoever. He uses the PWM peripheral as a DAC to drive the speaker. I want to expand upon his project.
Fourth, I bought some thumbwheel switches from eBay that have digits 0-9. I want to build a cheap resistance decade box from those.
Fifth, I have a superprobe board that I got from the Dangerous Prototypes free PCB drawer. I need to order parts and populate that board.
Sixth, I want to work on a timer for the low voltage lights outside my house.
The main cause of delay is that I want to submit one parts order and order all the parts for all the projects to save on shipping costs. I've found that sitting down and doing parts selection can be an incredibly time consuming chore and I just haven't found the time to do finish that. I'm working on it.
Open source advocate Phillip Torrone has just written a piece for Make's website regarding the ethos of open source hardware. It's very well written, and worth the read.
Wow, I just realized that it's been a long, long time since I've posted any content.
I promise that I'm not neglecting my hacking/making! In fact, I've been spending vast amounts of time on a project that I hope to release shortly. Surprisingly, it's a software project, but it's definitely hardware related. In short, I recently realized how hard it can be to write sketches for the Gameduino platform and I want to remedy that.
I'm not ready to release any details yet, but I'm spending tens of hours per week on this project (which my wife and sons aren't too thrilled about) and am making steady, measurable progress.
I'm very excited about the project and can't wait to get it out to the world. It's just not ready yet. I just wanted to stop by here and assure you (that is, the two people who read my blog) that I am indeed hard at work on a worthy hacking project and the lack of posts on my blog doesn't indicate a lack of interest on my part.
The sous vide controller project is not dead. I have prototyped my circuit and have done a quick test. I have several WordPress articles queued up for publication but I have to make some final tweaks and take some photographs before I can publish them. Now that we're back from a family vacation, the wife is healthy, and Christmas is over, I'm hoping I can clear out some space in the garage to set up some example circuits and take some pics of the 'scope and get those articles published.
Well, somehow some vandals managed to take control of my website and replace my content with their own. I don't know how it happened and because it took a while for me to discover the issue, my ISP wasn't much help determining the root cause.
The good news is that the WordPress database was intact, and that I had a backup of my theme files. I was able to restore (for the most part) with little difficulty. I lost a custom table in one of my posts, and I'll have to replace a few graphics files. All in all, not a terrible spot to be in. I mentioned a while back that I wanted to invest some time in automated backups of my site. Guess what I never got around to. Maybe this will motivate me.
ST Micro just announced the STM32F4 series of processors and the STM32F4DISCOVERY kit. In fact, as I write this, ST is having a giveaway promo for the new discovery board. I have been thinking of an audio effects processor project for which this series of chips would be perfect. They have floating point processors, I2S interfaces, external memory interfaces, and high clock rates. (Yes, this is the same project idea I had for the Renesas RX600 contest. The two chips both have features that make them candidates for the project; I'll discuss the pros and cons of each in a later post.)
So, of course, I ordered one right away. (Especially when I found out it was free!) It was shipped remarkably quickly. Digi-Key is clearly the fulfillment house for ST based on the return address on the package. The board comes in clamshell packaging with little to no documentation.
I have 2 or 3 projects in my queue right now (and still have a wife, a job, and two kids) so it may be a while before I get to use this.
Although I'm an avid electronics enthusiast, my dirty little secret is that I haven't actually done any hobbyist electronics in quite a while. (It's been over a decade, I'm afraid, since I actually built a project.) I still pick up Circuit Cellar magazine each month and read the articles, but I've allowed life to take me away from actual blinkylights work. I've finally decided to press on with a project, any project, to get back into this hobby that I enjoy so much.
Sous vide cooking has apparently taken the maker/hacker community by storm. And I'm curious enough about it that I want to try it, too!
In case you haven't heard, sous vide (French for "under vacuum") cooking is a method of cooking food at a lower temperature, for a longer period of time, than traditional cooking methods. Food is placed into a vacuum sealed plastic bag, and the bag is placed into a temperature-controlled water bath. By cooking for a longer period of time, the heat gradient in the food is reduced so that food has an even 'doneness' throughout. By using a lower than normal temperature, the chemical reactions that take place during cooking can be better controlled, which allows for textures and tastes that cannot be achieved using traditional cooking methods. The combination of lower temperature but longer cooking time ensures that food is safe to eat.
Professional sous vide cooking apparatus can cost several thousands of dollars. Even a commercial unit intended for home use, the Sous Vide Supreme, sells for several hundred dollars.
So I've decided to build a sous vide cooking controller of my own design. I could, of course, clone one of the many DIY projects that others have documented on the web, but that deprives me of what, to me, is the most fun part of being an electronics hobbyist: the challenge of designing and creating a new circuit.
I also want to document the entire design and build process here on the blog so that those new to this hobby can get a glimpse into how projects go from idea to reality. So let's start!
At the most fundamental level, I need a controller that will maintain a constant temperature water bath. What design features are implied by that statement? Well, I'll need a container for water, for starters. I'll also need some way to add heat to the water, and a way to measure that heat.
After considering several options, I decided to use an off-the-shelf slow cooker ("Crock Pot") as the main part of the project. This takes care of both the container and the heating element.
To measure the temperature, I've decided to use a Dallas Semiconductor (since acquired by Maxim) DS18B20 digital temperature sensor. There are many electronics devices that can measure temperature. I chose the DS1820 because it requires no analog circuitry at all and gives a reading that's already calibrated in the real-world unit of degrees Celsius.
To control the heating element, I'm going to use use a TRIAC driven by an optoisolator. This is a fairly common application and there are examples of this circuit in many corners of the web.
To bridge the gap between the input (temperature measurement) and output (control of the heating element), I'm going to use a microcontroller. Of course, it is possible to design a circuit like this using only analog parts, but I'm a digital guy and my passion is microcontrollers. Besides, a microcontroller will allow me to add features that I couldn't get with an analog-only system.
The user interface will consist of a two-line character LCD and a few buttons. This will allow the user to program the temperature setpoint and desired cooking time, and will provide feedback to the user as the unit operates.
Lastly, I'll throw in some kind of audible alarm so the system can alert the user when the water bath is at the desired temperature (and cooking is ready to start), and when the cooking time has elapsed and the food is completely cooked.
At this point, a block diagram can be drawn to represent the entire system. Block diagrams like this are HUGELY useful in the design stages of an electronics project. In this stage, the details of each subsystem don't have to be known; only a general idea of the subsystems that will make up the final project and how they relate to each other. My block diagram looks like this (click for larger version):
Block Diagram of the Sous Vide Controller
That sums up the high-level design of this project. In the next installment, we'll select actual hardware and do some more detailed planning, and arrive at the first iteration of our project's schematic.
If you've been on any of the hardware hacking sites lately, you've surely seen the announcement of a new website, www.circuitbee.com.
I ignored the announcement for a few days, but it's made the rounds enough, and I've seen it enough, that I decided to check it out.
Although I haven't used the site yet, I have to admit the premise (and, from all appearances, the execution) is very cool and very much fills a need in the hacker community.
The issue is that of sharing schematics. When we hackers create a project, we almost always create a schematic in some kind of electronics design software, such as EAGLE. These programs store the schematic data in a proprietary format and allow display and editing of the schematic. Sharing that schematic, however, is problematic. Either we have to share the proprietary file, which means our users have to have the same software installed and load the file for themselves, or we have to export the schematic (generally as a .pdf or .jpg), and in my experience that always results in a poor quality image.
CircuitBee aims to solve that. By uploding your schematic files, CircuitBee generates a web-enabled view of the schematic that can be panned and zoomed onscreen. Having played with the site for all of 2 minutes, it looks like this site is a guaranteed success.
I'm currently working on a project; I certainly plan on uploading the files to CircuitBee when they're available.
