PID Light Control Lab Kit

Classes 11-12, typical ages 16–18. Age ranges vary by learner. Guided low-voltage electronics.

Activity engagement

120–180 minutes. Explore 20–35 min · Build 40–60 min · Test and discuss 60–85 min. Estimated time for building, testing and discussion.

What you need

A computer with a USB port and Arduino IDE is required and is not included. Wi-Fi/BLE experiments also require the local network or phone specified in the guide.

Included components

• Small Breadboard / Mini Solderless Board - 400 points — 1 breadboard
• Jumper Wire Combo - Male to Male, Male to Female and Female to Female Breadboard Connecting Wires (10 Qty Each) — 1 set
• Illustrated Activity Guide and Observation Sheets — 1 set
• Fitted Headers and Labelled Connection Leads — 1 set
• ESP32S 38Pin Development Board (WIFI+BLUETOOTH) — 1 controller board
• MICRO USB DATA CABLE — 1 data cable
• LDR Sensor (Light Dependent Resistor) - 5mm — 1 photoresistor
• 10K Ω 1/4 Watts (10 PCS) — 1 resistor
• 5mm LED - Red Color — 1 LED
• 330 Ω 1/4 Watts (10 PCS) — 1 resistor
• 10 K POTENTIOMETER — 1 potentiometer
• Opaque Light-Control Shade and Sensor Mount — 1 set

What you learn

• Feedback compares a measured value with a target.
• Proportional, integral and derivative terms affect response differently.
• Output and integral limits reduce saturation problems.

Connection guide

• 3.3 V → LDR → GPIO34 node → 10 kOhm → GND.
• Pot outer pins → 3.3 V/GND; wiper → GPIO35. GPIO25 → 330 Ohm → LED anode; cathode → GND.
• Fix LED and LDR facing one another under the opaque shade; do not short their leads.

Steps to make it

1. Disconnect all power and identify the supplied part labels and pinouts before wiring.
2. Mount the light path and wire both ADC1 inputs and PWM output.
3. Upload with Ki and Kd initially set to zero and observe response to a small target change.
4. Increase Ki modestly, then add a small Kd; compare settling time, overshoot and oscillation.
5. Temporarily shade the light path and observe recovery without changing the target.
6. Change only the named parameter for the extension, repeat the controlled trials, save observations and disconnect power afterward.

Programming resources

Arduino IDE: install esp32 by Espressif Systems 3.x; select ESP32 Dev Module for the supplied classic WROOM board. Serial Monitor: 115200 baud. GPIO is 3.3 V only.

Uses the selected board core libraries.

Download starter sketch

Test challenge

Use the same target step for P-only, PI and PID trials; keep geometry and room light fixed.

Observation task

Time, target, measured ADC count, duty, gains, overshoot and settling behaviour.

Expected result

The LED duty adjusts to reduce light error within available brightness and sensor limits; tuning depends on the actual setup.

If it does not work

Verify divider orientation: more LED light must increase the reading. If feedback runs away, switch off and fix orientation before increasing gains.

Try next

Add integral anti-windup conditional on output saturation and compare with the bounded-integral starter.

Use and supervision

Use only the supplied low-voltage DC parts. Disconnect power before rewiring; check polarity and labelled pinouts. No soldering or exposed mains connections. Adult guidance is recommended.

How this experiment works

Download class activity guide

Cover illustrations show component types. Functional animations explain principles and are not recorded prototype tests. Follow the supplied connection labels and pinouts.