Circuit Diagram
How to Build It
- Place the LM358 op-amp on the breadboard.
- Power it: pin 8 to the positive rail, pin 4 to GND.
- Build a voltage divider with the photoresistor and a fixed resistor, feeding the non-inverting input (pin 3).
- Build a second voltage divider with a potentiometer, feeding the inverting input (pin 2) — this sets the threshold.
- Connect the output (pin 1) through a resistor to an LED, then to GND.
- Power the circuit and cover the photoresistor with your hand — the LED should turn on.
Bill of Materials
| Product | Code | Qty |
|---|---|---|
| Potentiometer knob block | 57 211 57212 | 1 |
| Integrated circuit | — | 1 |
| Photoresistor LDR | OKY0102 | 1 |
| LED (3/5/10mm, SMD, power) | l-934ID-12V | 1 |
| Resistor | DR47K-8/9 | 1 |