x ARCHIVE: Hardware__Electronics Box (v2b)
We got around to making a cleaner version of the bluetooth electronics box. To review, the basic electronics needed for mkturk are a digital control signal for gating a pump. This can be achieved with a circuit that uses a transistor in series with the power supply and pump as done in this tutorial, except we will be putting our pump downstream of the transistor on the emitter side. A second digital line controls an indicator LED that blinks when the microcontroller powers on, when bluetooth signals are received, and when the pump is on. Note that the following circuit diagram shows an arduino when in reality a blenano module is used for control input via bluetooth and digital output to pump.
This circuit only takes a few minutes to wire up on a breadboard. A quick and easy way to go from a breadboard to a compact solution is to use this protoboard which is a PCB version of a breadboard.
Adafruit Perma-Proto Half-sized Breadboard PCB 3-pack (Adafruit, Part# 571) 1x
RedBearLab BLE Nano + MK20 USB nRF51822 (Sparkfun, Part# WRL-14071) 1x
Altech enclosure 3.7"x2.56"x2.24", clear lid (Allied Electronics, Part# 70074464) 1x
LED 5mm assorted 20-pack (Sparkfun, Part# 12062) 1x
Diode 1N4001 1A 50V [(Allied Electronics, Part# 70015967)] (http://www.alliedelec.com/hvca-1n4001/70015967/) 2x
NTE128 Transistor [(Allied Electronics, Part# 70214874)] (http://www.alliedelec.com/nte-electronics-inc-nte128/70214874/) 1x
Adafruit micro-usb-b female breakout (Amazon, Part# B00KLDPZVU)
Jameco DC female jack Breadboard male 10-pack (Amazon, Part# B00R5C9AQQ) 1x
Toggle Switch [(Allied Electronics, Part# 70156044)] (http://www.alliedelec.com/te-connectivity-mta106f/70156044/) 1x
DC Power Cable Male, 5.5/2.1mm (Amazon, Part# B0054D80LE) 1x
Female-to-Female Jumper Wires 4-inch & 8-inch (Amazon, Part# B01L5ULRUA)
Male-to-Female Jumper Wires 4-inch & 8-inch (Amazon, Part# B01L5UKAPI)
Male & Female Header Socket Row Strip (Amazon, Part# B019WOPOHI
Since the protoboards are nicely labeled, it's basically paint (solder) by numbers to make more of these. This is our medium term, small scale solution. For making more than a couple of these, a PCB is eventually desired. The advantage of this protoboard implementation is that it is more flexible if you want to change anything or add components. As you'll see, there is lots of extra space left on the board should we want to add more sensors or actuators in the future.
Rows 1-6: BLE Nano
Row 7: Digital Line from Nano Pin 29
Rows 7-8: 180ohm resistor
Rows 8-9: Photodiode
Rows 9-13: MicroUSB-b Connector (row 9=ground, row 13=5V)
Row 17,13: Diode
Row 15,17: Diode
Row 13: Transistor C(ollector)
Row 14: Transistor B(ase)
Row 16: Transistor E(mitter)
Row 14: Header for Digital Line from Nano Pin 28
Row 17: Positive, rear Pin of DC Jack (cut PCB trace to isolate negative, front pin of DC jack. Negative, front pin needs to be tied to row 15 needs to be tied to ground)
Row 13,18: Toggle Switch
Rows 16-18 are soldered together underneath the board to make a junction
And don't forget to power the Nano on rows 1-2 on the other side of the board!
Protoboard is cut to fit in a 2.5" box 
Right angle pins are added to the digital gold pads of the ble nano. Headers for easy insertion and removal of the nano are added to the protoboard 
An LED is placed to receive a control signal from the nano 
Solder top of pins for micro-usb connector 
Location of microusb connector on protoboard. Only 5V and ground pins are used. Resistor for LED has been added 
Add diodes and transistor 
The diodes connected in way that saves space around the layouts for the usb & dc connectors 
Add DC jack. Note that front center pin and back center pin are signal and ground,respectively. Lateral pin is shield. On the underside of the protoboard, the lead from power needs to be cut and separated from the other holes in that row. 
A toggle switch is added that goes straight from 5V to the pump +terminal. 
What the underside of the board looks like after all is said and done 