Stuff for the Make to Learn Youth Contest:
What did you make?
I made a sonic screwdriver TV-B-Gone combo as a birthday present for a friend. It started out as a crazy idea that I had one day, but transformed into the awesome finished product you see above. In preparation for this, I learned all about how the TV-B-Gone circuit worked so I could modify it to use the least amount of parts possible. In order to build it, I ordered parts off of Digikey, Amazon and Sparkfun, then I assembled everything according to my plans. I used my Raspberry Pi, a breadboard, my trusty soldering iron, wire cutters, needle nose pliers, an exacto knife, solder, and desoldering wick.
How did you make it?
The idea came to me one day while I was browsing around online, I was looking for potential ideas for a birthday present, and I came across several homemade Sonic Screwdrivers online, and thought, "Hey! I can do something like that!" and it worked out perfectly because my friend is a huge Doctor Who fan. I ended up using my dad's help to split it open and his clamps and plastic cement to seal it back up. My initial design called for a capacitor to help smooth out the current, but in the end it ended up not fitting, so I had to leave it out. I could probably have left out the resonator too, but I had already bought it, so there was no point in wasting it if it fit.
Where did you make it?
I made this at home, upstairs in the room with all of my dad's model trains. He has a small work area up there that I'm allowed to solder at, and it's got this really comfortable chair to sit in, which definitely helps with my ADHD. I had to balance this with homework because the last day of the term was today, and I had to make sure I had all my grades in order.
What did you learn?
Honestly, this turned out amazing! I only had two gripes, and those were the range and the fact that I had to leave out the capacitor. It functions just fine, but you can see the UV LED flicker ever so slightly when in use. I feel the most proud about programming the microcontroller, it was a first., that combined with this being my first complex circuit made me really happy. All in all, it was a project full of firsts for me, and considering I designed the whole thing myself, and it actually works, made me a really happy person the last week or two. It doesn't hurt that my friend loves it either!
Step 1: Designing
Once the idea came to me, I had to design the blasted thing. I started initially by researching the schematics for the TV-B-Gone. I knew this was what I needed to use, but there was no way I could fit all of that inside any Sonic Screwdriver. Meanwhile, I started looking at various Sonic Screwdrivers available online, and at first, I wanted to use this, but not only was it too small, but it didn't make noise, and had multiple inaccuracies from the one on the show. Ultimately, I settled for this instead, a bit pricier, but altogether worth the extra money. The added price meant that I had to bring in extra friends, and luckily they were willing to chip in as long as they got credit too. With the Sonic Screwdriver picked out, I had to get back to designing the circuit that would flash the codes. Mine is heavily based off of Ladyada's TV-B-Gone, but with fewer parts in order to fit inside of the Screwdriver. After a quite lengthy conversation with JeonLab, I concluded that the only parts that I had to order were a microcontroller, a resonator, an LED, a transistor, and two resistors. I also ordered a capacitor as you will see in the pictures I took, but ultimately left it out due to size restrictions. Another help was Panik, from the Raspberry Pi forums. As you can see here, he helped me learn how to program an Attiny with my Pi. Once I had the parts figured out, I drew up a set of schematics shown above using SchemeIt, a free online schematics designer provided by Digikey.
Step 2: Parts List
Okay, enough of me droning on, let's make this thing!
Items you will need:
Max Power IR LED Kit from Sparkfun (could be replaced with appropriate transistor, LED, and resistors to save money, we won't use the circuit board anyways)
10th Doctor's Sonic Screwdriver (I got mine off of Amazon because Thinkgeek was out of stock)
220uF Capacitor (Helps smooth out power, but makes it an extremely tight fit)
Raspberry Pi (Or any other avr programmer. I will provide instructions for a Raspberry Pi though)
Desoldering Wick (Useful if you make mistakes, and helps clean up the circuit board if you decide to rewire everything)
Step 3: Program the Microcontroller
You can skip this step if you either purchased a preprogrammed Attiny from Adafruit, or you have another programmer you can use that instead.
To start, I'm going to assume you have a Raspberry Pi and you know how to run commands and connect the GPIO pins to a breadboard. Before you can program the Attiny, you need to first install a patched version of Gordon's AVRdude. Run the following commands:
sudo dpkg -i avrdude_5.10-4_armhf.deb
sudo chmod 4755 /usr/bin/avrdude
After you have completed that, you may now make the connections from the Raspberry pi to the Attiny. I have included a pinout of the GPIO and the Attiny. Ensure to power off your Pi.
(Raspberry Pi --> attiny85)
MOSI --> MOSI (PB0)
MISO --> MISO (PB1)
SCLK --> SCK (PB2)
CE0 --> RESET (PB5)
3V3 --> VCC (pin 8)
GND --> GND (pin 4)
When you are done, turn your Pi back on and run the following commands:
Avrdude -c gpio -p t85 -U lfuse:w:0xfe:m -U hfuse:w:0xdf:m -U efuse:w:0xff:m
Then, make sure you have your oscillator connected, because the Attiny won't run without it. The outer pins go to pin 2 and 3 on the Attiny, and the middle pin goes to ground.
After that, run this command:
avrdude -p t85 -c gpio -v -U flash:w:tvbgone.hex
Congratulations! As long as AVRDude didn't spit out any errors, everything probably went fine!
Step 4: Assembly
I'd like to apologize up front for a lack of documentation on my part. This was hurriedly built in time for a birthday, and so I forgot to take pictures for most of it. I'll show you what I have, and do my best to draw the rest. Start by unscrewing the slide and removing the batteries. Then split it down the side with an exacto knife or similar. Remove the black column in the middle of the clear section, and remove the cap at the top. Inside, you will find a button, some wires, a circuit board, and an LED. Assemble your circuit as compact as possible, and remember to put the leads on the LED through the silver column on top, and make sure you insulate things properly as you go. Connect the power leads that would go to the battery in the schematic to the positive side of the switch as shown on the included drawing. Insert the batteries and go test it out. To use, get very close to a TV, point, and hold down the button until it turns off. This may take up to 70 seconds. If it works, you should be able to see the UV LED light up, as well as the Sonic Screwdriver making sounds, followed by the TV turning off. As a confirmation, you can also look at the LED's through a camera. If everything is properly working, you should see both of the LED's light up. If everything works, very carefully fold and compact the circuit until it fits again. You may have to move some things in order for everything to fit. When you are done squishing everything back inside, test it again. Second to lastly, ensure that the both LED's will fit by removing plastic from the blue piece on the top. And finally, seal it shut with plastic cement, and clamp it overnight to ensure it won't break open again.
Step 5: Final Word
If you enjoyed my instructable, please vote, rate, and comment. It really makes my day when I open up my email and see that people enjoyed my work, and I tend to post more often as well! I might be willing to make these for $100 labor. If you're interested, shoot me a message.