Solar garden light with dusk switch
Charges by day, lights at night. By day the little panel charges the cell through a Schottky diode, and the bright LDR holds the transistor’s base low so the LED stays off. At dusk the LDR’s resistance soars, R_b turns the transistor on, and the LED lights from the cell; the diode stops the cell draining back into the dark panel.
Build it in the labGuided build, test sheet and fault finding, free in your browser.
Parts list
Test procedure
Each test has an expected value and a pass range, like a factory test sheet:
- Day: charging
- Day: LED off
- Night: LED on
- Night: no drain into the panel
How it works
What it does: Charges by day, lights at night.
Build it (guided or ready-made), then run its test procedure below. Every test has an expected value and a pass range, just like a factory test sheet.
Background
Millions of these sit in gardens: a 2 W panel, one cell, one transistor.