BeginnerAudio
Adjustable 555 Tone Generator
Turn the NE555 into an adjustable square-wave tone source for a piezo element; explore frequency by ear.
Parts from the database
- NE555P × 1Square-wave timer
Other supplies
- passive piezo buzzerCommon build supply
- 10 kΩ resistorCommon build supply
- 100 kΩ potentiometerCommon build supply
- 10 nF timing capacitorCommon build supply
- 100 nF bypass capacitorCommon build supply
- breadboardCommon build supply
- regulated 5 V supplyCommon build supply
- jumper wiresCommon build supply
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Connections
- Use the standard NE555 astable connection: pins 2 and 6 tied, timing capacitor from the joined node to ground, pin 7 between RA and RB.
- Use 10 kΩ for RA from +5 V to pin 7; use the 100 kΩ pot as RB from pin 7 to pins 2/6.
- Pin 1 to ground, pin 8 and RESET pin 4 to +5 V; place 100 nF between pins 8 and 1.
- Drive a passive piezo from pin 3 through a 100 Ω resistor to ground. Do not use a loudspeaker directly.
Build steps
- Build the timer without the piezo and check that pin 3 oscillates if you have a meter with frequency mode.
- Add the piezo and turn the pot slowly through its range.
- Try a 1 nF or 100 nF timing capacitor to hear how the pitch range changes.
- Record the component values and pitch range so the build can be repeated.
Software and firmware setup
This is a hardware-only circuit; no firmware is required.
Test your build
The piezo should produce an audible tone that changes pitch as the pot moves. The circuit is a square-wave source, not a music-quality audio amplifier.
Troubleshooting
- If silent, check that the buzzer is a passive piezo and that pin 3 is oscillating.
- If the pitch range is outside hearing, change the timing capacitor value.
- If the 555 warms up, disconnect power and check for a wiring short.
Safety and limitations
Use a small piezo and low-voltage supply. Keep the sound comfortable and do not connect headphones or speakers directly.
Manufacturer and platform documentation
Community Notes for This Project
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