Table 1. Component costs of the LoCHAid.
| Components | Mass Production Cost | |
|---|---|---|
| Earphones (i) | $0.04 | |
| Audio Jack (ii) | $0.03 | |
| 2 x 1000 pF Capacitor (iii) | $0.02 | |
| 2 x 1 uF Capacitors (iv) | $0.02 | |
| 1 x 15 uF Capacitor (v) | $0.01 | |
| 5 kΩ Trim Pot Potentiometer (vi) | $0.06 | |
| 6 pronged—Slide Switch (vii) | $0.03 | |
| Open Source Electret Microphone (viii) | $0.10 | |
| Open Source Stereo Class D 3.7 Amplifier (ix) | $0.48 | |
| Circuit Board (x) | $0.05 | |
| 3D Printed PLA Casing (xi) | $0.06 | |
| 2 x 6.8 kΩ Resistors (xii) | $0.02 | |
| Total Cost Without Batteries | $0.92 | Total Cost With Batteries |
| 2 AA Alkaline Batteries and Holder (xiii) | $0.13 | $1.05 |
| 3 V Coin Cell Battery and Holder (xiv) | $0.06 | $0.98 |
The table lists the costs for acquiring individual components in bulk of 10000 pieces. The LoCHAid is assumed has been created from the following: (i) a set of earphones (ModelGF-923, In-Ear, 3.5mm Connector, from Boluo Golden Fortune Electronic Manufacture Factory, www.alibaba.com, P/N 60249739970), (ii) a audio jack (1/4” 3.5mm PCB Mount Female Socket 5 pin, from Yueqing Daier Electron Co. LTD, from www.alibaba.com, M/N EJ-214M); (iii) 2 1000pF capacitors (SMD/SMT 1000 pF 50V Multilayer Ceramic Capacitor, from Part Rescue Technology, from www.alibaba.com, M/N VJ0603Y102KXACW1BC); (iv) 2 1 uF capacitors (SMD Ceramic Capacitor 1uF 50 V, from Shenzhen Yuzens Technologies Co. Ltd, from www.alibaba.com, M/N CL10A105KB8NNC); (v) a 15uF capacitor (250V 450vac 15uF polyester capacitor, from Shenzhen Weitaixu Cpacitors Co., Ltd., from www.alibaba.com, M/N cbb61 15uF run capacitor); (vi) a 5 kΩ Trim Pot Potentiometer (Cermaic Bourns Variable Resistor, from Changhoo Kennon Electronics Co. Ltd., from www.alibaba.com, M/N 3006P); (vii) a 6 pronged slide switch (Mini Slide switch, from A-Key Electronics Technology, from www.alibaba.com, M/N MSS-22D16); (viii) an electret microphone module (Utilising MAX9814, from Shenzhen Ronghai Electronics Co. Ltd, from www.alibaba.com, M/N MAX9814); (ix) a stereo 3.7 W amplifier (MAX98306 Stereo 3.7W Class D Amplifier, P/N MAX98306ETD+, from www.maximintegrated.com. P/N MAX98306); (x) a circuit board (Prototyping Universal Board PCB Double Sided 4 x 6 cm board, from Shenzhen Androw Technology Limited, D/C YC045-53, www.alibaba.com P/N 60529535100); (xi) 3D printed PLA casing is obtained in bulk (PLA plastic granules for 3D filament 3D material PLA plastic pellet, from Yasin, Guangdong China, from www.alibaba.com, M/N PLA pellets, JSC-310); (xii) 2 6.8 kΩ Resistors (Resistors 0.4 W 6.8 kΩ, from Shanhai Group Limited, from www.alibaba.com, M/N MMA02040C6801FB300). The LoCHAid can be powered by several types of batteries as long they deliver 3V; here, we present two forms—(xiii) 2 AA batteries (Entop 1.5V AA Carbon Zinc, from Suzhou South Large Batter Co., Ltd., www.alibaba.com P/N 60643508502) which needs a battery holder (2 AA 1.5V Battery Holder, from Yueqing Daier Electronics Co., Ltd., from www.alibaba.com, M/N BH5-2003); (xiv) or a coin cell battery (3V Lithium Button Cell, from Shenzhen Gmcell Technology Co., Ltd. P/N CR2032, www.alibaba.com, P/N 60251728326) which needs a coin cell holder ($0.03 (Black 3V Coin Button Holder, Yueqing Daier Electronics Co., Ltd., from www.alibaba.com, M/N BH2032-3). *All links and prices last accessed September 17, 2019.