Electronics Basics L13: Make it beep — the 555 as a tone maker
// WHAT YOU WILL LEARN
Same 555 circuit with a much smaller capacitor (≈ 10 nF) blinks hundreds of times a second — fast enough to hear as a tone from a small speaker or buzzer.
// LESSON NOTES
Can one little chip make music? 🎵🔊
⏱️ Last time our 555 timer blinked an LED once a second (10 µF capacitor).
🔁 Swap it for a 10 nF capacitor — 1,000× smaller.
⚡ Now it charges and drains about 1,000 times a second = a 1,000 Hz square wave.
🔊 Put a small speaker (or a piezo buzzer) on pin 3… BEEP!
🎹 Smaller capacitor = higher note:
100 nF ≈ 100 Hz · 10 nF ≈ 1,000 Hz · 1 nF ≈ 10,000 Hz
f ≈ 1.44 ÷ ((R1 + 2·R2) × C)
Read the voiceover (transcript)
- Can one little chip make music? Listen!
- Last time, the five five five blinked once a second.
- Now swap its capacitor for one a thousand times smaller!
- So fast, it flips a thousand times a second!
- Guess: what does a speaker do with that?
- It beeps!
- Smaller capacitor, higher note!
- Next: the Zener diode. Follow for Part fourteen!
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