I figure the computer controlled part of that setup could be built using an arduino and one of the many cheap and small touch screen LCDs available today.

http://www.ghielectronics.com/products/dotnet-gadgeteer

There are lots of handy modules like Relays, Touch screens etc that can make putting simple things like that together a breeze

http://www.ghielectronics.com/catalog/category/274/ 

http://www.ghielectronics.com/catalog/product/327

http://www.ghielectronics.com/catalog/product/364

http://www.ghielectronics.com/catalog/product/376

 A selection of the above parts will be living under my Christmas tree for the next month, make all the lights flash

If you have stronger electronics skills there are many, many other options out there these days.

One of my projects was replacing the microcontroller on this automatic cat litter box. I renamed it the "TurdMaster 2000".

The original problem was that my cats don't quite uhm, cover up when they are done, and the original design called for the feline to cover up before leaving the litter box. It would then sit for 7 minutes until the product was "baked" and then go into its roll action that would dump it out at the bottom.

My updated design changed it from Bake 'n Roll to Shake, Bake 'n Roll, which resolved the design flaw in my case. So after sensing the cat has left, it would go into a Shake mode where it would perform a few roll motions so that said product gets covered up, then lets it Bake for the required 7 minutes before dumping out.

Unfortunately one of the cats never got used to the noise it made and ultimately I had to get rid of it. Pity as I was rather fond of the TurdMaster 2000 after all the time and effort I put into it...

14 hours ago, BitFlipper wrote

[TurdMaster 2000 story]

Awesome.

I have a netduino lying around. I wanted to get into that sort of stuff but I quickly found that I don't have enough knowledge of electronics. I then bought this book to learn the basics, but found that there's quite a steep learning curve between really basic stuff like Ohm's law and more advanced things. Also, I then realised that if I bought all the things I needed for the experiments in the book I'd have to spend hundreds of euro's.

Also I was blowing up LED's like crazy for some reason.

It's too bad, I still have a bunch of ideas I want to try out. There's something fun about the idea of seeing your stuff work "for real" instead of just on a computer screen.

It should give you enough confidence to start tinkering or, at least, it should make reading more complex textbooks a lot simpler.

2 days ago, Bas wrote

Also I was blowing up LED's like crazy for some reason.

2v LED + 9v battery = Firecrackers

Complete projects are nice, and there's a cartload of precooked modules and shields out there, but trying to make your own hardware can be frustrating at first (and smelly).

3 days ago, Bas wrote

I have a netduino lying around. I wanted to get into that sort of stuff but I quickly found that I don't have enough knowledge of electronics. I then bought this book to learn the basics, but found that there's quite a steep learning curve between really basic stuff like Ohm's law and more advanced things. Also, I then realised that if I bought all the things I needed for the experiments in the book I'd have to spend hundreds of euro's.

If you need anything, I have a community college and a bachelors degree in electronics

Also I was blowing up LED's like crazy for some reason.

Too much current,.

Say you have 5V output, a LED (which is basically a diode) takes 0,6V. You are left with 4,4V. Your LED probably needs about 20mA. So you need a resistor to limit the current.

4.4V / 20mA = 220 Ohm resistor would do the trick.

It's too bad, I still have a bunch of ideas I want to try out. There's something fun about the idea of seeing your stuff work "for real" instead of just on a computer screen.

Run them by me, always fun to tinker!

Digital electronics is not that hard, it's either 0, 1 or an illegal value.

Analog electronics is HARD.

Agree with what you said, other than LED forward voltages are typically closer to 2V - 3V, much higher than the forward voltage of regular diodes.

I also have a BS in electronics and used to be heavily into all sorts of electronic circuits. I've since switched to software development but my dream job is one that combines electronics with software. Unfortunately every time I look into those kinds of jobs, I find them to be few and far between, and they don't seem to pay anywhere near what a software development job pays.

Actually I used to love analog electronics, and designed and built all sorts of weird and wonderful things. I had a ZX Spectrum 48 and designed and built an 8-bit successive approximation ADC out of resistors and transistors, no ICs. It basically uses a series of transistors biased to turn on/off based on a threshold voltage, and subtract half the voltage if "on" and passes the remaining voltage to the next stage.

Another project was designing and building a class-D amplifier (this was long before they became somewhat common). This is basically a powerful binary switching amplifier that can only be in one of 2 states: High or Low voltage (+50V or -50V). Then using pulse width modulation at a high switching frequency (250KHz in my case), and passing the square wave through a lowpass filter, you can get an analog signal out that can power a speaker. The beauty is that since the output transistors (mosfets) are either fully on (0V across them) or fully off (0 current through them), the theoretical power loss is 0 Watts (since power is volts x current). This means you can have a very powerful amplifier using no or very small heatsinks, and have it be very compact.

My 1st microcontroller project was an 8051 driving a bunch of large 7 segment LEDs allowing you to feed MIDI into it where it would show you the song position in realtime. The idea was to mount it somewhere in a recording studio and then everyone can see exactly where in the song the current recording was at.

Ah, those were the days...

I hear you, I've moved to software development as well since there are few jobs in electronics.

1 day ago, Maddus Mattus wrote

@Blue Ink:

Digital electronics is not that hard, it's either 0, 1 or an illegal value.

Analog electronics is HARD.

Yes, digital electronics is easy and fun, on paper. Physical circuits will never miss the opportunity to remind you that there's a difference between abstractions and reality. To the uninitiated even a using a simple voltage regulator or a transistor can be a challenge. The internet made a difference, with the availability of datasheets and reference designs, but the first steps are still hard.

8 hours ago, Maddus Mattus wrote

@BitFlipper:

I hear you, I've moved to software development as well since there are few jobs in electronics.

Funny, I did the opposite. I started off as a Software Engineer and then went to the "hard side". Firmware is still software, just a lot more interesting as you cannot get closer to the metal than that.

Decades later I'm still caught as a software developer at heart, though: apparently I use too may LEDs in my circuits (it's for debugging purposes, I swear) and my firmware tends to abstract the hardware away too much. Still plenty of time to learn how to do it right.

This example controls two relays from a PC software application: http://startingelectronics.com/projects/arduino-projects/arduino-tiny-relay-shield/

And this one reads a temperature sensor (maybe you can switch the machine off when the ice cream is cold enough?): http://startingelectronics.com/projects/arduino-projects/arduino-tiny-temperature-shield/

They both use the Processing language for the PC application and an Arduino.

Just my 2c worth