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Solar Panel Voltage Converter for IoT Devices

Yes we CAN exploit indoor lighting

Based on a Labs project | March 2015 | Find it here
Solar Panel Voltage Converter for IoT Devices
This circuit exploits the unique ability of the LTC3129 and LTC3129-1 to start up and operate from an input power source as “weak” as 7.5 µW (microwatts) — making them capable of operating from small, low-cost solar cells with indoor light levels less than 200 lux.
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Extra info / Update
* Stores energy from indoor lighting
* Solar panel Vout 5 V typ., 42 µA
* Input power down to 7.5 µW usable
* 3.2 V typical out
* Choice of LTC3129 or LTC3129-1 converter IC, board configurable for either
* Easily configurable for many output voltages
* Optional backup battery
* Optional super-charge capacitor
* Ready-assembled unit with LTC3129-1 fitted, 3V3, MPPC mode.
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The BOM (Bill of Materials) is the technically exhaustive listing of parts and other hardware items used to produce the working and tested prototype of any Elektor Labs project. The BOM file contains deeper information than the Component List published for the same project in Elektor Magazine. If required the BOM gets updated directly by our lab engineers. As a reader, you can download the list here.
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Component list
Component List
R1 = 2.26M? 1%, 0.063W, 0603 *
R2,R6 = 2.43M? 1%, 0603 (R2*)
R3,R5 = 4.22M? 1%, 0603 (R5*)
R4 = 4.99M? 1%, 100mW, *
R7 = 2.2M? 1%, 0603 *
R8–R12 = 0?, 0603 *

C1,C2 = 22nF, 25V, 0603
C3,C4 = 10pF, 25V, 0603
C5,C6 = 2.2µF, 25V, 0603
C7 = 470µF, 6.3V, case D
C8 = 22µF, 10V, 0603
C9 = 4.7µF, 25V, 0603
C10 = 0.47F, 5.5V, Super Capacitor, radial

IC1 = LTC3129EMSE#PBF or LTC3129-1 *
T1 = FDC6312P (Newark/Farnell # 1700713)
D1 = BAT54WS-E3-08

L1 = 4.7µH 20%, SMD

BAT1 = Lithium Battery, CR2032, coin cell, 3V, 20mm, with PCB mount holder
K1,K2 = 2-pin pinheader
Solar panel, AM-1815CA, 58.1x48.6mm (Panasonic)
PCB # 130560-1 v. 1.0 from Elektor Store
Ready assembled unit, # 130560-91 from Elektor Store. Version: LTC3129-1, 3.3V out, MPPC, battery excluded.

* Component, value and/or use subject to user configuration; see text.

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