Introduction
This project combines a throwie, a simple LED circuit, with a bit of 3D modeling.
Materials
- Rare earth magnet
- An LED
- CR2032 3V lithium coin cell
- 220Ω resistor
- Tape (strapping tape is recommended, but not required)
- Caliper or other measuring instrument
Software used
- 3D modeler of your choice
- Netfabb Studio Basic
- ReplicatorG
A Throwie
A throwie is a very simple circuit where an LED is illuminated by connecting it across the terminal of a small lithium coin cell. The first LED Throwie was a piece of electronic urban graffiti invented by Graffiti Research Labs in New York City in 2006.
Why is it called a throwie?
It's called a throwie because the circuit is connected to a magnet, which allows you to throw the circuit at any ferromagnetic surface, like a locker, and it'll stick to the surface.
LEDs are cool because they're tiny and long lasting (up to 10 years). Unlike incandescent bulbs, LEDs don't get hot. They also don't consume a lot of power.
LEDs come in many colors, brightnesses, sizes and shapes.
LEDs are polarized. The positive side (the side connected with the + side of the battery) is the longer leg and is referred to as the anode. The shorter leg is called the cathode. If you take your finger and feel around the edge of the plastic casing, you might feel a chipped edge, this is also a way to determine the cathode.
You won't hurt the LED if you accidentally plug it in backwards. It just won't turn on.
The color of an LED is determined by the semiconductor material and not by the package (plastic body). Different colored LEDs require different amounts of voltage to light up. Red, green, and yellow LEDs typically require 2.2V-2.4V. Super-bright white and blue LEDs can require up to 3.4V.The optimum voltage is referred to as forward voltage (VF).
Most LEDs require 20mAh of current flowing from the battery, and most batteries supply more than 20mAh, so you need to use a resistor to limit the flow of current to each LED so it won't burn out.
VF Forward Voltage is also referred to as Voltage Drop. It is the minimum amount of voltage needed to light up an LED.
lV Luminous Intensity is the amount of light emitted from an LED in a particular direction. It is measured in millicandela (mcd). It might be helpful to think of this property as brightess. The greater the millicandelas the brighter the LED.
IF Forward Current is the amount of current the LED uses.
Viewing Angle is the spatial distribution or spread of light. It is expressed in degrees that measure the width of the light beam. LEDs with a small viewing angle produce a more focused beam, and LEDs with larger viewing angles produce a softer more dispersed beam.
| Type | Color | IF | VF Typ | VF Max | Luminous Intensity | Viewing Angle | Wavelength |
|---|---|---|---|---|---|---|---|
| Standard | Red | 30mA | 1.7V | 2.1V | 5mcd@10mA | 60° | 660nm |
| Standard | Yellow | 30mA | 2.1V | 2.5V | 32mcd@20mA | 60° | 565nm |
| Super bright | Red | 30mA | 1.85V | 2.5V | 500mcd@20mA | 60° | 660nm |
Back to the Throwie Circuit
www.evilmadscientist.com
www.evilmadscientist.com
Here's the Schematic
- You can either solder (better) the resistor to the anode lead or you can twist it together.
- Cut off a piece of tape. Tape the cathode lead of the LED to negative terminal of your battery and the resistor lead to the positive terminal of your battery. Keep the tape very tight as you wrap.
- Place the magnet on the positive terminal of the battery and continue to tightly wrap the tape. The magnet should be held firmly to the battery. Keep the magnet away from conventional hardrives, credit cards and other data storage devices.
Challenge
Your task is to create an aesthetic housing for the electronics. One that will hide the electronics, but show the light. Use a 3D modeler of your choice to build your model.
- Make measurements of your circuit and keep in mind that the model will shrink a little bit when printed.
-
Design your model using millimeters
The table below can be used to convert between fractional and/or decimal inches and metric millimeters.Inches Metric Fractional Decimal mm . 0.0039 0.1000 . 0.0079 0.2000 . 0.0118 0.3000 1/64 0.0156 0.3969 . 0.0157 0.4000 . 0.0197 0.5000 . 0.0236 0.6000 . 0.0276 0.7000 1/32 0.0313 0.7938 . 0.0315 0.8000 . 0.0354 0.9000 . 0.0394 1.0000 . 0.0433 1.1000 3/64 0.0469 1.1906 . 0.0472 1.2000 . 0.0512 1.3000 . 0.0551 1.4000 . 0.0591 1.5000 1/16 0.0625 1.5875 . 0.0630 1.6000 . 0.0669 1.7000 . 0.0709 1.8000 . 0.0748 1.9000 5/64 0.0781 1.9844 . 0.0787 2.0000 . 0.0827 2.1000 . 0.0866 2.2000 . 0.0906 2.3000 3/32 0.0938 2.3813 . 0.0945 2.4000 . 0.0984 2.5000 7/64 0.1094 2.7781 . 0.1181 3.0000 1/8 0.1250 3.1750 . 0.1378 3.5000 9/64 0.1406 3.5719 5/32 0.1563 3.9688 . 0.1575 4.0000 11/64 0.1719 4.3656 . 0.1772 4.5000 3/16 0.1875 4.7625 . 0.1969 5.0000 13/64 0.2031 5.1594 . 0.2165 5.5000 7/32 0.2188 5.5563 15/64 0.2344 5.9531 . 0.2362 6.0000 1/4 0.2500 6.3500 . 0.2559 6.5000 17/64 0.2656 6.7469 . 0.2756 7.0000 9/32 0.2813 7.1438 . 0.2953 7.5000 19/64 0.2969 7.5406 5/16 0.3125 7.9375 . 0.3150 8.0000 21/64 0.3281 8.3344 . 0.3346 8.5000 11/32 0.3438 8.7313 . 0.3543 9.0000 23/64 0.3594 9.1281 . 0.3740 9.5000 3/8 0.3750 9.5250 25/64 0.3906 9.9219 . 0.3937 10.0000 13/32 0.4063 10.3188 . 0.4134 10.5000 27/64 0.4219 10.7156 . 0.4331 11.0000 7/16 0.4375 11.1125 . 0.4528 11.5000 29/64 0.4531 11.5094 15/32 0.4688 11.9063 . 0.4724 12.0000 31/64 0.4844 12.3031 . 0.4921 12.5000 1/2 0.5000 12.7000 . 0.5118 13.0000 33/64 0.5156 13.0969 17/32 0.5313 13.4938 . 0.5315 13.5000 35/64 0.5469 13.8906 . 0.5512 14.0000 9/16 0.5625 14.2875 . 0.5709 14.5000 37/64 0.5781 14.6844 . 0.5906 15.0000 19/32 0.5938 15.0813 39/64 0.6094 15.4781 . 0.6102 15.5000 5/8 0.6250 15.8750 . 0.6299 16.0000 41/64 0.6406 16.2719 . 0.6496 16.5000 21/32 0.6563 16.6688 . 0.6693 17.0000 43/64 0.6719 17.0656 11/16 0.6875 17.4625 . 0.6890 17.5000 45/64 0.7031 17.8594 . 0.7087 18.0000 23/32 0.7188 18.2563 . 0.7283 18.5000 47/64 0.7344 18.6531 . 0.7480 19.0000 3/4 0.7500 19.0500 49/64 0.7656 19.4469 . 0.7677 19.5000 25/32 0.7813 19.8438 . 0.7874 20.0000 51/64 0.7969 20.2406 . 0.8071 20.5000 13/16 0.8125 20.6375 . 0.8268 21.0000 53/64 0.8281 21.0344 27/32 0.8438 21.4313 . 0.8465 21.5000 55/64 0.8594 21.8281 . 0.8661 22.0000 7/8 0.8750 22.2250 . .8858 22.5000 57/64 .89063 22.6219 . .9055 23.0000 29/32 .90625 23.0188 59/64 .92188 23.4156 . .9252 23.5000 15/16 .93750 23.8125 . .9449 24.0000 61/64 .95313 24.2094 . .9646 24.5000 31/32 .96875 24.6063 . .9843 25.0000 63/64 .98438 25.0031 1 1.000 25.40 . 1.0039 25.5000 . 1.0236 26.0000 . 1.0433 26.5000 . 1.0630 27.0000 . 1.0827 27.5000 . 1.1024 28.0000 . 1.1220 28.5000 . 1.1417 29.0000 . 1.1614 29.5000 . 1.1811 30.0000 . 1.2205 31.0000 1 1/4 1.2500 31.7500 . 1.2598 32.0000 . 1.2992 33.0000 . 1.3386 34.0000 . 1.3780 35.0000 . 1.4173 36.0000 . 1.4567 37.0000 . 1.4961 38.0000 1 1/2 1.5000 38.1000 . 1.5354 39.0000 . 1.5748 40.0000 . 1.6142 41.0000 . 1.6535 42.0000 . 1.6929 43.0000 . 1.7323 44.0000 1 3/4 1.7500 44.4500 . 1.7717 45.0000 . 1.8110 46.0000 . 1.8504 47.0000 . 1.8898 48.0000 . 1.9291 49.0000 . 1.9685 50.0000 2 2.0000 50.8000 . 2.0079 51.0000 . 2.0472 52.0000 . 2.0866 53.0000 . 2.1260 54.0000 . 2.1654 55.0000 . 2.2047 56.0000 . 2.2441 57.0000 2 1/4 2.2500 57.1500 . 2.2835 58.0000 . 2.3228 59.0000 . 2.3622 60.0000 . 2.4016 61.0000 . 2.4409 62.0000 . 2.4803 63.0000 2 1/2 2.5000 63.5000 . 2.5197 64.0000 . 2.5591 65.0000 . 2.5984 66.0000 . 2.6378 67.0000 . 2.6772 68.0000 . 2.7165 69.0000 2 3/4 2.7500 69.8500 . 2.7559 70.0000 . 2.7953 71.0000 . 2.8346 72.0000 . 2.8740 73.0000 . 2.9134 74.0000 . 2.9528 75.0000 . 2.9921 76.0000 3 3.0000 76.2000 . 3.0315 77.0000 . 3.0709 78.0000 . 3.1102 79.0000 . 3.1496 80.0000 . 3.1890 81.0000 . 3.2283 82.0000 . 3.2677 83.0000 . 3.3071 84.0000 . 3.3465 85.0000 . 3.3858 86.0000 . 3.4252 87.0000 . 3.4646 88.0000 3 1/2 3.5000 88.9000 . 3.5039 89.0000 . 3.5433 90.0000 . 3.5827 91.0000 . 3.6220 92.0000 . 3.6614 93.0000 . 3.7008 94.0000 . 3.7402 95.0000 . 3.7795 96.0000 . 3.8189 97.0000 . 3.8583 98.0000 . 3.8976 99.0000 . 3.9370 100.0000 4 4.0000 101.6000 . 4.3307 110.0000 4 1/2 4.5000 114.3000 . 4.7244 120.0000 5 5.0000 127.0000 . 5.1181 130.0000 . 5.5118 140.0000 . 5.9055 150.0000 6 6.0000 152.4000 . 6.2992 160.0000 . 6.6929 170.0000 . 7.0866 180.0000 . 7.4803 190.0000 . 7.8740 200.0000 8 8.0000 203.2000 . 9.8425 250.0000 10 10.0000 254.0000 20 20.0000 508.0000 30 30.0000 762.0000 40 40.0000 1016.000 60 60.0000 1524.000 80 80.0000 2032.000 100 100.0000 2540.000 - After you have made your design, check it in netfabb and repair if necessary.
- Export part and open file in ReplicatorG
- Print
- Embed
- Throw
A Better Circuit
Throwies are great, but they won't last forever.
Add a switch to your circuit so that you can turn it on and off.
$("p:not(p:eq(2))").css("border","2px solid pink").css("padding", ".5em");
Sources:http://www.evilmadscientist.com/article.php/throw
http://mtifall09.wordpress.com/2009/12/12/assignment-11-personal-public-computing-throwies/
http://graffitiresearchlab.com/
http://mtifall09.wordpress.com/2009/12/12/assignment-11-personal-public-computing-throwies/
http://graffitiresearchlab.com/