Sound Trigger Light Kit

Classes 5-6, typical ages 10–12. Age ranges vary by learner. Guided low-voltage electronics.

Activity engagement

45–65 minutes. Explore 5–10 min · Build 15–20 min · Test and discuss 25–35 min. Estimated time for building, testing and discussion.

What you need

No computer required. An adult helps inspect connections.

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
• 4 CELL AA BATTERY HOLDER WITH SWITCH / COVER — 1 holder
• AA BATTERY — 4 battery (individual units)
• Regulated 5 V Power Supply with Short-Circuit Protection — 1 power supply
• LM393 Sound Sensor Module — 1 sensor module
• 5 V Sensor Output Driver with Trigger Selector — 1 interface circuit
• 5mm LED - Red Color — 1 LED
• 330 Ω 1/4 Watts (10 PCS) — 1 resistor

What you learn

• A microphone signal crossing the comparator threshold produces a short output pulse.
• A comparator turns a changing sensor signal into a digital threshold output.
• A separate output driver keeps the sensor signal separate from its load.

Connection guide

• sound sensor VCC/GND → regulated +5 V/GND; its labelled DO output → driver IN.
• Driver VCC/GND → the same supply; use its supplied active-low/high trigger selector to match the module.
• Driver OUT → 330 Ohm → LED anode; LED cathode → GND.

Steps to make it

1. Disconnect all power and identify the supplied part labels and pinouts before wiring.
2. Switch the supply off and identify the sensor DO terminal; do not confuse it with AO.
3. Connect the sensor, preassembled labelled driver and output using the connection card.
4. Power on and adjust the sensor sensitivity at the baseline condition until the output is stable.
5. Make gentle claps at 10, 30 and 60 cm; keep background sound similar.
6. Repeat five controlled trials, changing only one condition, then switch off and dry/clean the sensing surface as appropriate.

Test challenge

Make gentle claps at 10, 30 and 60 cm; keep background sound similar.

Observation task

Distance, sensitivity setting, five trials and successful detections.

Expected result

A microphone signal crossing the comparator threshold produces a short output pulse. The driver makes that change visible or audible.

If it does not work

Check the DO pin, shared ground, sensitivity setting and driver trigger selector. A brief sensor pulse gives only a brief output; this is not a latching alarm.

Try next

Discuss why a threshold microphone module cannot measure calibrated decibels.

Use and supervision

Use only supplied 5 V DC. Keep fingers away from the buzzer opening and use a comfortable sound level. Disconnect power before rewiring.

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.