Specifications
| Type | Active buzzer with its driver: an NPN transistor switch, a flyback diode and an indicator LED. HIGH on SIGNAL beeps, LOW stops |
|---|---|
| Buzzer | Huawha TMB12A05, electromagnetic, with its own oscillator. 2400 ± 300 Hz, one fixed note. Ø12 × 9.5 mm, through-hole, shipped under a paper seal to peel off |
| Loudness | At least 95 dB at 10 cm at 5 V (datasheet); 95.5 to 97.8 dB on the datasheet's ten-part test report. About 3 dB quieter at 3.3 V, typical |
| Rated voltage | 5 V, for 3 to 7 V. The buzzer runs from VCC |
| Current | 30 mA max (datasheet); about 22 mA typical at 5 V and 15 mA at 3.3 V, plus about 3 mA for the LED on 5 V. None of it flows through SIGNAL |
| Driver | S8050 NPN transistor between the buzzer and GND, hFE 200 to 350. SIGNAL feeds its base through 1 kΩ: about 2.6 mA from a 3.3 V pin, 4.3 mA from 5 V |
| SIGNAL | 1 kΩ to the transistor's base and nothing else. No pull-down: a pin that is HIGH or pulled up while your board boots sounds the buzzer |
| Supply | 5V on VCC, on any board: VCC never reaches SIGNAL, so it is safe beside a 3.3 V board. 3V3 works, quieter |
| Protection | SS14 Schottky diode across the buzzer for the switch-off kick. Nothing to add |
| Indicator | Red LED and 1 kΩ from VCC to the transistor: lit while the buzzer is driven. Not a power light |
| Pins to wire | 3 of the 4: GND, VCC and SIGNAL. NC is connected to nothing on the board |
| Header | 4-pin right-angle male, 2.54 mm pitch: GND, VCC, NC, SIGNAL, with GND on the square pad |
| Board | 22.4 × 30.4 mm, two 4.8 mm mounting holes 16 mm apart. The front prints ACTIVE HIGH, the back BEEPS WHEN GPIO IS HIGH |
| In the box | 1 × TK36 block. It also ships inside the TinkerBlock kits |
What it does
One note, on demand. The black can is an active buzzer: a coil, a thin metal disc and an oscillator all inside it, so it sounds its own 2.4 kHz note from plain DC. The rest of the board switches it: an S8050 transistor between the buzzer and GND, a 1 kΩ from SIGNAL to the transistor's base, a diode for the coil's kick at switch-off, and a red LED that lights while it is driven.
SIGNAL HIGH switches the transistor on and the buzzer beeps; LOW switches it off. The buzzer's current, about 22 mA from 5 V, flows from VCC and never through your pin, which gives the base about 2.6 mA at 3.3 V.
The page this replaces called the buzzer a piezo element, put its note near 2 kHz, and suggested tape over the hole to quieten it. The datasheet says an electromagnetic buzzer at 2400 ± 300 Hz, and warns against covering the hole.
Two things to know before wiring
- There is no pull-down on SIGNAL. Whatever your pin does before
setup()runs, the buzzer does. GPIO 0, 43 and 44 on an ESP32-S3 dev board beep from power-up, and GPIO 0 can stop the board running your sketch at all. The handbook uses GPIO 4. - VCC is the buzzer's supply, and it is a 5 V part. Wire VCC to 5V on every board: it never reaches SIGNAL, so that is safe beside a 3.3 V microcontroller. 3V3 works, about 3 dB quieter.
Wiring, in four lines
- GND to your board's GND.
- VCC to 5V: an Uno's 5V, the 5V pin of an ESP32 or ESP32-S3 board on USB, or a Pico's VBUS.
- SIGNAL to GPIO 4 on an ESP32-S3 or ESP32, D9 on an Uno, GP15 on a Pico.
- NC to nothing: it is connected to nothing on the board.
Then pinMode(pin, OUTPUT) and digitalWrite(pin, LOW) first in setup(),
and digitalWrite(pin, HIGH) to beep.
Where to start
The handbook below is nine short articles, each with a working figure. The first beep is the whole build in three wires and a few lines, and quiet at boot is the one page about choosing the pin.
For how it works, read a switch in the ground wire and five volts or three. For alarms and confirmations that do not stop your sketch, beeps without delay(). If it will not beep, when it does not beep.
When it doesn’t work
- It beeps as soon as I power my board.
- The board has no pull-down on SIGNAL, so the buzzer follows whatever your pin does before the sketch starts. On an ESP32-S3 dev board GPIO 0 is pulled up by the BOOT button and sounds it from power-up; GPIO 43 and 44 are the serial port and do the same. Use GPIO 4, and make pinMode OUTPUT and digitalWrite LOW the first two lines of setup().
- Should VCC go to 3V3 or 5V?
- 5V, the buzzer's rated voltage: an Uno's 5V, the 5V pin of an ESP32 board on USB, a Pico's VBUS. It is safe beside a 3.3 V board because VCC never reaches SIGNAL. 3V3 works too, inside the buzzer's 3 to 7 V range, about 3 dB quieter.
- Can PWM change the volume?
- Not usefully. analogWrite switches the whole buzzer on and off hundreds of times a second, and its own oscillator's note comes out chopped at that rate: sometimes quieter, usually rougher. The datasheet does not cover it. 3V3 on VCC is a little quieter; for real control, use a passive buzzer.
- I want it to play a tune.
- Wrong part: the note is made inside the buzzer at 2400 ± 300 Hz, and tone() only chops it. TK37 is the passive buzzer, which plays the frequency your sketch gives it.
- Should I take the paper seal off?
- Yes. It says REMOVE SEAL AFTER WASHING and is there to keep cleaning fluid out when the board is washed after soldering. The buzzer beeps with it on, but the datasheet warns that covering the sound hole can make it run unsteadily. For the same reason, tape over the hole is not a volume control.
- The LED lights but it does not beep.
- The LED sits beside the buzzer on the transistor, so SIGNAL, VCC and GND are all fine. The fault is the buzzer or its leads. Check the seal is the only thing over the hole.
