DIY littleBits

Let's make DIY littleBits!  For original circuits, visit littleBits.cc . 

I will be adding more steps to this instructable every time I manage to make another DIY littleBit.  So come back often and follow this instructable  to see new bits tutorials.  *Added since initial publication: light trigger*  I change the original circuits based on parts availability and my own preferences and ability.  I volunteer for the Fresh Air Fund, and my hope is that I can learn enough to offer a free afternoon workshop this summer for the children who visit my town just 45 minutes north of NYC.

The connection method I currently use between bits involves 3 header pins on both the left and right sides and female to female jumper wires.  There is no kanban mechanism to prevent miswiring, so the user must be careful when connecting DIY bits.  One idea is to use alternating male and female pins on alternating sides with male to female color coded jumper wires (red=+VCC, green=signal, black = GND).  If you decide do use alternating male and female pins and jumpers, then the male header pins should be on the left of the bits; this is to prevent dangling live male jumper wires from crossing each other and creating a short circuit. 

PARTS:  If not stated in each individual step, you will need solder, hot glue, 22 gauge stranded insulated wires, perfboard, male (maybe also female as you like) pins, jumper wires, heat shrink tubing (electrical tape is ugly but will suffice), and a method for labeling your DIY bits.  Many bits require an op amp chip, which can get pricey if you are buying them individually from the store.  I recommend buying larger quantities of chips from www.digikey.com.  The Digikey part number for the LM741 op amp chip is LM741CNNS/NOPB-ND ; at publication time, I was able to buy this chip for $0.70.  For labeling bits, I use #6 plastic from the recycling bin (also sold as shrink film by www.grafixarts.com). 

Tools required include wire stripper, soldering gun, helping hands, needle nose plyers, hot glue gun, and a method for cutting perfboard (I scored it with a sharp knife and snapped it over a straight edge ruler, but some prefer to use a dremel).  The most important tool is a good book; I recommend Timer, Op Amp & Optoelectronic Circuits & Projects by Forrest M. Mims III http://www.forrestmims.com/engineers_mini_notebook.html 

Step 2: POWER!

The first thing we need is POWER!!!  The original "p1 power" circuit requires a power regulator that Radio Shack does not sell, so instead I bought the 5V regulator which is most commonly used by hobbyists - the LM7805.

Parts list:
1) 9V battery
2) 9V battery snap with red and black wires
3) Perf board cut to 9 x 12 full holes
4) LM7805
5) Capacitors: 0.1uF ceramic disk (code 104), 1.0uF (maybe dipped tantalum), 10uF electrolytic ... Pay attention to polarity and substitute as risk will allow.
6) Resistor: one 330 ohm
7) one small red LED
8) spdt slide switch - a single throw switch may suffice
9) 3 header pins
10) 3 jumper wires

Procedure:
1) Breadboard and test that V and S output 5V.
2) Arrange on perfboard & solder.
3) Test that V and S output 5V.
4) Hot glue any weak connections, including the output pins to the perfboard.  I hot glued this bit to a blue 4x6 lego plate, as power is coded blue in littleBits.
5) Great job!  You can use this bit to power any projects that require 5V. 

Step 3: RGB LED - light sensitive!

Parts list:
1) Perf board cut to 9 x 12 full holes
2) LED: 5mm tricolor (red/blue/green) - Radio Shack part #2760028
3) Resistors: 3 x 330 ohm (220 ohm may suffice - test it on a breadboard first), 3 x Cds photocells (photoresistors) - Radio Shack part #276-1657.  I used the 2 large photoresistors that come in this pack for Red and Blue and the medium for green.
4) LM741 op amp - Radio Shack part #276-0007 or Digikey part #LM741CNNS/NOPB-ND ...  The output pins on the 741 differ from the LV321, which is used in the original littleBits.cc schematic for this bit.  Please note the difference!
5) connection pins (3 on left side and 3 on right side)
6) heat shrink tubing
7) 3 jumper wires

Optional:
If you are not interested in making your RGB LED light sensitive, then you will need 3 10K potentiometers instead of the 3 photoresistors.

Procedure:
1) Breadboard and test that your LED can make the 3 main colors and a variety of other colors in between.  You can do that by either covering over the photoresistors with different opacities (black electrical tape is almost totally opaque, while your fingertip is probably 1/2 opaque) or, if you used 10K potentiometers,  use a flat head screwdriver to dial in your colors.
2) Arrange on perfboard & solder.
3) Test that V and S output 5V against G.
4) Hot glue any weak connections, including the pins to the perfboard.  
5) Make a label and consider color coding this bit according to the littleBits code.  LED's are an output, so this would be green.  Lego's anyone?
6) Great job!  I put in front of the TV to make a mood lamp.  Imagine placing the photoresistors beneath a motorized device that blocks the light from another LED in a dynamic intermittent manner.

Step 4: Long AND Bright LED

Parts list
1) Perf board cut to 9 x 12 full holes
2) LED: 5mm high brightness white - Radio Shack part #2760017
3) Resistor: one 220 Ohm
4) LM741 op amp - Radio Shack part #276-0007 or Digikey part #LM741CNNS/NOPB-ND ...  The output pins on the 741 differ from the LV321, which is used in the original littleBits.cc schematic for this bit.  Please note the difference!
5) connection pins (3 on left side and 3 on right side)
6) heat shrink tubing
7) 3 jumper wires

Procedure:
1) Breadboard and test that your LED is bright.  Make your LED a few inches long by soldering stranded insulated wire to the leads, but not so long that it gets snagged on things.  You can solder your resistor directly to a lead and cover that with heat shrink tubing or electrical tape, or you can display the resistor on the perfboard. 
2) Arrange on perfboard & solder.
3) Test that V and S output 5V against G.
4) Hot glue any weak connections, including the pins to the perfboard. 
5) Make a label and consider color coding this bit according to the littleBits code.  LED's are an output, so this would be green; that is why I hot glued green legos to my bit.  You could use anything green, really.
6) Connect to your existing DIY bits.  If you did not use the 741 op amp chip, your bright LED may be dim depending on how many bits you have connected together.  If you want a bright LED, an op amp chip is a must.

Step 5: button

Parts list:
1) Perf board cut to 9 x 12 full holes
2) SPST momentary button - I took mine from an old broken toy.  These will vary in sizes and shapes.
3) Capacitor: one 0.1uF either ceramic disk or polyester film will do just fine
4) Resistor: one 1M Ohm (a.k.a. 1,000K Ohm)
5) connection pins (3 on left side and 3 on right side)
6) 3 jumper wires

Procedure:
1) Breadboard and test that your button is working with a DIY LED bit plugged into your breadboard.  Use separate rails on your breadboard for Signal in and Signal out (refer to image).  If you find your LED is fading in and out, you may have used too large of a capacitor.  If your LED is skittering on and off, your old used button may be poor.
2) Arrange on perfboard & solder.
3) Test that V and S output 5V against G.
4) Hot glue any weak connections, including the pins to the perfboard.
5) Make a label and color code this input bit pink.
6) Connect to your existing DIY bits.

Note:  I made no changes to the littleBits.cc circuit, so please refer to their original design as found on their website.

Step 6: inverter

Parts list:
1) perf board cut to a size that will accommodate the size of your inverter chip. I happened to have 74AC240N, so I used a pre-printed circuit board that can take up to a 20 dip chip.
2) capacitor: 0.1uF
3) resistor: 1M Ohm (a.k.a. 1,000K Ohm)
4) inverter chip - the original design calls for 74AHC1G04DCK.  Please refer to your inverter chip's datasheet for the correct pinout.  The diagram I show here refers to the 74AC240N.
5) connection pins (3 on left side and 3 on right side).  I ripped mine out of a computer the neighbor put out for trash. 
6) 3 jumper wires

Procedure:
1) Breadboard and test that your inverter is working.  In order to test, you will need DIY Power + DIY button + breadboarded inverter +DIY LED bit plugged into your breadboard.  Use separate rails on your breadboard for Signal in and Signal out (refer to breadboard image).  This setup will yield an LED normally on; when you press the button, the LED will turn off.
2) Arrange on perfboard & solder.
3) Test that V and S output 5V against G.
4) Hot glue any weak connections, including the pins to the perfboard.
5) Make a label and color coding this bit according to the littleBits code.  Inverter is coded orange.
6) Connect to your existing DIY bits.  This bit is a lot of fun with a pulse bit and a couple LED's.

Step 7: pulse

This is my absolutely favorite bit!  My pulse runs fast at a 50% duty cycle, because that's the way I like it.  If you want longer pulses, you can breadboard different variations of the same circuit.  Please refer to the original design at littleBits.cc and to Forrest Mim's "LED flasher" design in his book (refer to intro step in this instructable for full reference).

Parts list:
1) Perf board cut to 9 x 12 full holes can accommodate the quick and dirty pulse, but make the chip at least 9 x 16 if you want to really do your homework and include the op amp chip.
2) 555 chip
3) LM741 op amp chip (optional?)
4) Capacitors: 10uF, 0.01uF  Please pay attention to polarity! 
5) Resistors: 100 Ohm, 1K, 10K, 10K micro potentiometer
6) Transistor: NPN - I used a 2N2222
7) one LED - I kept this on my final bit, but you may want to simply use it for breadboard testing.
8) 3 header pins
9) 3 jumper wires

Procedure:
Using the 555 can be overwhelming to a new user, so take it slowly.  If you have access to Snap Circuits and the 8-Pin IC Socket # 6SC ?U8, then try building some 555 circuits by KRA5H.  I built several designs by this instructable member, http://www.instructables.com/member/KRA5H/ , like this one:http://www.instructables.com/id/Install-an-LED-in-a-Tone-Generator-Circu... ...  That is one way to learn about the 555, but you can also simply use a breadboard.

1) Breadboard and test that V and S output 5V.  Take your time on this step, and really consider what capacitors and resistors you want to use.
2) Arrange on perfboard & solder.
3) Test that V and S output 5V.  Test that the pulse duration changes when you dial the potentiometer with a flathead screwdriver.
4) Hot glue any weak connections, including the output pins to the perfboard.
5) Label pulse and color code it as a pink bit.
6) Great job!  With the following circuit, you can now make flashing police lights:  Power, pulse set to a short duration, RGB led, inverter, long/bright led.  You will need either a red or a blue pen cap to cover the long/bright led, and the RGB led should be set to either blue or red.

Step 8: lever (roller) switch

Step 9: label your bits!

As mentioned in the introduction, you can use the #6 clear plastic from your recycling bin to make labels. 

Procedure:
1) Hand write the bit name on #6 plastic (or Shrink Film made by www.grafixarts.com ) with a black sharpie marker.
2) Sand the back side of your plastic with medium weight (300 - 400 grit) sandpaper.
3) Color the sanded side with white colored pencil.  Maybe you will use this step to color code your bits - use a different color besides white.
4) Preheat oven between 300 and 350 degrees.
5) Cut out words and place them on "medium weight cardboard, teflon sheet, parchment paper or vellum (do not bake on bare metal or on stoneware)." - according to Shrink Film package directions.  Do the same thing for your #6 plastic.  It's the same stuff.
6) Bake for 2-3 minutes or heat with an embossing tool.  Do not remove from oven until piece is flat.  If still curled, flatten with a spatula while still hot.  Do not touch with your hands until fully cooled.
7) Glue label to bit wherever you like.  I used Elmer's white glue for this.

Step 10: light trigger

This is one of the more challenging bits to make. 

Parts list:
1) Perf board...  I try to keep all my DIY littleBits small, but this one has a lot of big elements.  I cut mine to 9 x 17 full holes, which was not enough to accommodate the AND gate.  My solution at the time was to insulate the AND gate wires with black electrical tape and fold it over the top.  A better solution would have been to start with a larger perf board. 
2) two LM741 op amp chips
3) Capacitors: 0.01uF  - You can cheat and go without this, but it is good form to keep it in your circuit.  Google "bypass capacitors" to learn more.
4) Resistors: 4 x 100K, one 100K micro potentiometer, one (large?) Cds photoresistor.  More resistors in an AND gate...
5) one AND gate - Two good options are either the 74LS08 Quad AND Gate chip, which is available on Radio Shack shelves in a variety pack labeled "Low Power IC Kit" (part # 276-0294) or you can make your own with transistors and resistors you already have in your kit.  The parts required for your self made AND gate are: 2 x 2N2222 NPN transistors, 2 x 10K resistors, one 47 ohm resistor.  I included a picture of my AND gate.  Google "transistor AND gate" for more information.  
6) one DPDT slide switch
7) 3 header pins
8) 3 jumper wires

Procedure:
1) If you have the Forrest Mims III book, which was listed in the first step, assemble the "Light Activated Alerter" and "Dark Activated Alerter" circuits.  The hand written circuit I show here that says "Test" on the top right is the basic boiled down circuit.  Notice that it does not show a green Signal in line coming in on the left.  This is not a complete littleBits circuit; it is just a breadboard demonstration!  Leave some room on the left and right side of your breadboard for the rest of the circuit. 
2) If you are new to DPDT switches, there is enough information out there to drown anyone.  I labeled the two lines coming from the "voltage dividers" W and X; you can think of the 3 and 2 pins going into the second op amp chip as Y and Z.  These labels correspond with the diagram on this switch tutorial website: http://www.1728.org/project2.htm .
3) Refer to littlebits.cc for the complete "light trigger" circuit.  It is not shown here on my instructable. 
4) Arrange complete circuit on perfboard.  Consider how easily you can flip the switch, and try not to put the photoresistor in the shadow of any other components. 
5) Test that V and S output 5V.  Test that the bit functions as it is described on littleBits.cc .
6) Hot glue any weak connections, including the output pins to the perfboard.
7) Label light trigger and color code it as a pink bit.
8) Woohoo!  Pat yourself on the back and click the "I made it" button. 

Step 11: DIY bits under construction

The following DIY bits are under construction in my house: 

1) motor - I have made a working 6 transistor H-Bridge with a slide switch that changes direction on my motors.  However, I only have toy and electric toothbrush motors, and I need geared motors.  :(

2) timeout - I have breadboarded a timeout bit with Snap Circuits (see image).  In it's current state, it is only in "on-off" mode.  That means when you push a button, the timeout will send an on message to the next bit until time runs out.  Then it will shut off.  I still need to add the SPDT switch,  Mosfet N Channel, and the second op amp chip in order to give it that second "off-on" function.  I am trying to arrange the components to make room for all that.

3) voice recorder - I found a $2 voice recorder that was barely audible in it's original format.  Maybe I'll add an amplifier.  I'm sure this will be a fun bit to create!

License: Attribution-NonCommercial-ShareAlike.

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