This Week on James's Bench

Mystery Module #001

Look closely. Make a guess. Then follow James and Mμ through the engineering process: observe, identify, test, measure, and learn.

James's BenchEverything has a story. Let's discover what this one is.
PD803BDG SS10100 SS10100 0 B+B− L+L−
Mμ inspecting a circuit board

1. Look Closely

Before revealing the answer, inspect the parts and traces. What do you notice?

SS10100

Two high-current Schottky rectifier diodes.

PD803BDG

A MOSFET used as a switching or pass element.

Zero-Ohm Link

A configurable jumper used to connect part of the circuit.

2. Make Your Guess

Could it be a battery protection board? A reverse-polarity protector? A solar controller? Write down your best hypothesis before continuing.

3. Reveal the Answer

Automatic Solar Street Light Controller.

The board detects when solar-panel voltage falls at dusk and automatically switches the LED load on. During daylight, the load turns off and the battery can charge.

4. How It Works

Daytime

Solar-panel voltage is present. The controller keeps the lamp off and allows the battery to charge.

Nighttime

Solar-panel voltage falls below a threshold. The MOSFET switches battery power to the LED load.

Why Schottky?

Lower forward-voltage loss means more harvested energy reaches the battery and load.

5. Engineer's Challenge

  • Measure the minimum operating voltage.
  • Measure quiescent current during the day.
  • Measure the light-switching threshold.
  • Test maximum safe continuous load current.
  • Compare measured performance with the seller's claims.

6. Build It

Connect a small solar panel, rechargeable battery, and LED load to create a dusk-to-dawn solar light.

Watch the Recorded Class Find the Parts in the Store Download the Worksheet