Alarm, telephone, multimedia, horn, active, passive, buzzer22*07

First of all, we must understand that active and passive "sources" here refer not to power sources but to oscillating sources. In other words, the active buzzer has a shock source inside, so it will sound as soon as it is energized. However, there is no oscillation source in the passive part, so if DC signal is used, it cannot be chirped. It must be driven by 2K~5K square wave. Active buzzers are often more expensive than passive buzzers because there are many oscillating circuits inside. This is the way to separate by driving principle. Then let's look at the difference in appearance (as shown in the figure below) The Difference between Active Buzzer and Passive Buzzer From the appearance of figs. a and b, the two buzzers seem to be the same, but on closer inspection, the heights of the two buzzers are slightly different. the height of active buzzer a is 9mm, while the height of passive buzzer b is 8 mm. If the pins of the two buzzers are placed upward, it can be seen that the one with green circuit board is a passive buzzer, and the one without circuit board and sealed with black glue is an active buzzer. Difference of Resistance Measured by Multimeter Use multimeter resistor Rxl to test: connect the "+"pin of buzzer with black probe, and the red probe will touch back and forth on the other pin. If the buzzer with 8Ω (or 16Ω) resistance is a passive buzzer that triggers a clicking sound. If a continuous sound can be emitted and the resistance is over several hundred ohms, it is an active buzzer. At the same time, the active buzzer can continuously sound when directly connected to the rated power supply (the new buzzer is marked on the label); The passive buzzer, like the electromagnetic speaker, needs to be connected to the audio output circuit to produce sound. The advantages of passive buzzer are: 1. Cheap 2. The sound frequency can be controlled, and the effect of "Doramifasolasi" can be achieved. 3. In some special cases, a control port can be multiplexed with LED. The advantages of active buzzer are: convenient program control.