DIY Simple Solar Lamp

Lets make a simple solar lamp for nameplates,etc

We will make a very simple circuit using a single NPN transistor

You can replace any components with alternatives

You can design and print the casing the way you like.

You will need the following:

SL100 transistor

Solar panel 5V

18650 Liion Cells

LDR and 4.7k pot

1W Leds

Capacitors and resistors

Optional:

3d printer

Nut and bolts

This is the basic circuit diagram

The resistor value will adjust your output current for led hence brightness

Pot will adjust the sensitivity to sunlight

IMPORTANT

I used a simple voltage step down to get a constant voltage of 4.2v for charging

and used a big battery as buffer against over charge and over discharge

It is recommended to use a BMS for avoiding these issues

I used Fusion 360 and Ender3 V2

You can use anything as per convenience

I made the circuit on a small perf board for convenience

Roughly pasted everything using feviquick and fevicol

Make sure to test everything before installing

For attaching the cover I pasted the nuts of in the corners and installed using the bolts

from outside