Active vs Passive buzzer for ESP32

Thread Starter


Joined Nov 29, 2015
Hey. I plan to use a buzzer to signal when a human hand is detected with a proximtiy sensor. My ESP32 is doing a lot of processing and work (WIFI, MQTT messages, driving LED strip , reading sensor values) hence I want to know whether the Passive buzzer is the right choise(I currently have just passive buzzer). I am not entirely sure how does PWM generation work on ESP32, but I certainly dont want any interrupts to happen in my system since I drive an LED strip and any interrupt may cause a glitch. I have found ledc library which generates PWM on ESP32 but would like to know more about the actual PWM generation on the ESP32 boards. Should I avoid using passive buzzer and just use simple active buzzer?


Joined Mar 19, 2019
For active all you need is VDC, an active alarm out V. For passive you need some kind of AC signal which can be PWM or the alarm output VDC is used to trigger an oscillator to generate a frequency signal to drive the passive buzzer. A contact out VDC to an active buzzer is pretty simple.