SOL+
VIN
R1
1K
R3
22Ω
R4
5.1Ω
3
3
2
Q2
2N2222
Q1
2N2222
SWITCH
Out+
Out–
Bat+
Bat–
Bat–
Bat+
LED+
LED–
GND
GND
TP4056
R2
10K
D1
1N5819
SOL–
2
1
1
controls the brightness.
During the day, the solar cell generates voltage
and turns ON the transistor Q2, so it doesn’t have
the current bias to the base of transistor Q1. Q1 is
OFF so the LED will go out.
When there is no sunlight, there’s no solar
current to base Q2 so it will not conduct, but at
the same time, transistor Q1 will conduct. Now
the battery’s current will flow to the LED through
the resistors (R3 or R4).
The 3-pin button switch is used to connect
either R3 or R4 in the LED circuit. When the pole
is connected to R3, the brightness is Low (high
resistance, low LED current) and when connected
to R4, the brightness is High (low resistance,
high LED current). You can learn more about the
circuit in my video at youtu.be/Ll-qlYK30J0.
Build Your Solar Bottle Lamp
1. ASSEMBLE THE PCB
For assembling the PCB, you’ll need a decent
soldering iron, solder, and nippers. It is good
practice to solder the components according
to their height, beginning with the shortest
components: first solder the resistors, diode,
and transistors, then the female JST connectors,
the button switch, and finally the TP4056
module (Figure
C
). Trim the excess legs off the
components using a nipper.
Note that the button switch is mounted on the
bottom side of the PCB (Figure
D
).
+
GND
46 makezine.com
B
EMERGENCY! 3D-Printed Solar Lamp
C
D
M82_044-49_SS_SolarLamp_F1.indd 46M82_044-49_SS_SolarLamp_F1.indd 46 7/12/22 4:11 PM7/12/22 4:11 PM
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