I somehow sold the idea of having a gadget design class in high school this year.  I designed a relatively loose curriculum centered around the arduino platform and bought a bunch of parts to help get certain skill sets learned quickly (LCD’s, shift registers, servos, motors, etc).  Over the last week, I challenged my class to design their own final exam projects.  Here’s a summary of what is submitted so far:

1. Two students are taking an Arduino MEGA 2560, a 20×4 character display, ethernet shield (mostly for the SD slot), and a PS/2 keyboard and are building a basic computer.
2. Two students are building a controllable (via Playstation2 controller) robot that drives around and launches marshmallows.
3. One student is building an alarm clock with a handful of shift registers, 7 segment displays, and an RTC (DS1307).  The main control is a soft potentiometers (looks like and will be designed to be used like an iPod click wheel) and a couple buttons.

As for me?  I finally soldered together my video game shield kit I picked up a while back and am going to dive into some audio spectrum analysis and have some possible manipulation via wii nunchuck controller.

I can’t wait for presentation day — just over one month from now!

I’m hoping to write posts like this every month or two (depending on how active I am) as an update on what I’m working on and what I want to work on.

Practice Amp for Guitar

I’ve played guitar since I was 12 and have steadily built up my abilities and my collection of guitars, amps, and effects.  Some have come and gone over the years for various reasons. The big death was my Marshall Valvestate 8080 Combo that I’d had since I was 14.  Still one of the best sounding amps I’ve ever played.  I blew out part of the last amp stage as well as the 75W Celestion speaker in high school trying to use it as a bass amp (live and learn).  Repaired that blunder and it played great for many more years.  I picked up a Digitech RP-14D one summer and it has been the preamp for all of my guitar recordings since.  The line out of that board did blow out the input stage of my guitar amp over time.  The amp then sat in a garage for three years and is now more-or-less destroyed.  I might try to salvage some parts from it but my interest in bringing it back up to 100% again is definitely low.

I started thinking about buying guitar amp kits. The prices always kept me from trying and the idea would fade.  Then I stumbled across runoffgroove and beavis audio.  I ended up building Beavis’ Noisy Cricket (based on runoffgroove’s ruby).

Like a good hobbyist/engineer, I started with my trusty breadboard.  The circuit was relatively simple — a JFET preamp with an LM386 power amp.  I love that it’s called a power amp — it maxes out at 0.6 W.  I guess that’s powerful for some.  I’ll elaborate on that later.

The next part was tricky and annoying.  I had all panel-mount parts for the switches, jacks, and potentiometers.  These are problematic with a breadboard and the wire-hell that you can see forming in this picture was exactly that.

Here is the final-ish product (the one that worked at least — it’s the second build as the first one definitely did not work).  The amp is powered by a 12VDC supply and sounds VERY decent for an amp that cost next to nothing in parts to build.  I’m using an old stereo speaker right now as my output and plan to build a full cabinet for this thing in the near future.

Guitar Amp MK II

Still in what I might call the alpha planning stages is a 2x20W stereo guitar amplifier.  It will borrow the pre-amp from the noisy cricket and have an effects loop consisting of a few of the pedals on the right.  I plan on having them be physically a part of the amp as opposed to a plug-in module (as guitar effects tend to be).  The amplifier stage will end up being a kit from somewhere as I have little interest in designing that from scratch.  I’m also designing the amplifier to be run off of +5VDC and +12VDC (meaning I will use an ATX PSU) and also will be mostly digitally controlled via arduino and digital potentiometers.  This is a big project that I have yet to find the time to really draft up a plan of attack for.

DX Radio

I’ve always been fascinated with radio dx-ing (listening to stations/frequencies from far away) — caught the bug in high school when I picked up a radio station from Montreal while sitting in a parking lot in Virginia.  This project is also in a bit of an alpha stage and/or holding pattern for a wide range of reasons (the biggest one being that I’m really struggling with antenna design).  I discovered a Silicon Labs chip (Si4735) that is remarkably bad-ass in this space.  It’ll do all the heavy lifting for AM/FM/SW/LW radio and is a serial-controlled device.  I searched off and on for the chip or some sort of eval board with little success.  Then Sparkfun built something that I finally picked up.  I’ve definitely had it (almost) tune an FM station and have it output something that proved to me that I might succeed with this thing.  Again, my biggest hurdle with this is the antenna that is needed. I’m still working on that

Home WX/Sensor Network

We had the pipes to our washer freeze a few times this past winter.  I discovered pipe heat tape at that time and immediately started thinking of ways to have the power to the tape be controlled by a thermostat.  In parallel, I’ve been wanting to build a home weather station for a while and started turning both of these projects into one large network of weather-esque data.  This project is planned and I’ve done some proof-of-concept work and research so that I know certain things will eventually be possible.  The outdoor weather station will be complete with all gauges.  I also will place two more outdoor temperature sensors in different locations.

The temperature outside does not concern me much when the pipes are freezing.  The temperature in the basement where the pipes are located is what concerns me.  I will have two (or three, depending on my level of motivation) more temperature sensors in the basement along with humidity sensors to help monitor the basement space in our house.

When planned out, this system includes three separate micro-controllers — one master device and two slave devices.  The master will be directly connected with the main weather station (probably a sanguino or an arduino mega).  The slave micros (probably RBBB’s from ModernDevice) will handle the additional outdoor temp sensors as well as all basement data collection and control.  There will be a relay to toggle the state of the pipe tape based on the temperatures reported in that area.  I’m hoping to have this be an automatic process.

The devices will be connected via an I2C network with range extenders (can’t remember the chip I found — got it written down somewhere) that help with wire capacitance issues.  The display of the data will either be done by an LCD connected to the master controller or to a web page.

That’s all I’ve got for now.  I’m hoping the weather/sensor project happens this coming summer.  I keep wanting to work on the DX project but I tend to get frustrated quickly with that one and let it go. The guitar amp is definitely a back-burner project.

More coming soon — going to write up a few of my recent projects.  On the list are my attempts to build a small guitar practice amp, designing a whole-house sensor network, and miscellaneous furniture-ish things I built over the last week or two.

Soon… right now I’m going to sleep