The fundamental difference between active buzzer and passive buzzer is that the product requires different input signals; the ideal signal of active buzzer is DC, usually labeled VDC, VDD, etc. Because there is a simple oscillatory circuit inside the buzzer, it can convert the constant direct current into a pulse signal of a certain frequency, and the magnetic field alternates from the surface to drive the molybdenum plate to vibrate and pronounce. However, some active Buzzers can also work under specific AC signals, but the voltage and frequency of AC signals are very high, this mode of operation is generally not used.
Passive buzzers do not have an internal drive circuit. Some companies and factories call them loudspeakers. They are called loudspeakers in GB. The ideal signal of passive buzzer is Fang Bo. If the DC signal is given, the buzzer will not respond. Because the magnetic circuit is constant, the molybdenum sheet can not vibrate.
A simple way to distinguish active electromagnetic buzzer from passive electromagnetic buzzer
1. Visual inspection:
Comparing KS-12C01YE with KS-12D05YA, where "C" stands for passive and "D" stands for active; the former is 12*8.5 in shape and the latter 12*9.5 in shape, which are very similar. If the pins of the two buzzers are placed upward, one of the green circuit boards can be seen to be passive buzzer, without circuit boards but closed with black glue. One is the active buzzer.
But this is only the initial criterion for judgement, not the only criterion. If KS-1240T2PA is added, the identification is more complicated, its shape size is 12.5*6, this is the smallest piezoelectric passive buzzer on the market; as the market continues to develop, the quality requirements are increasingly high, now many manufacturers need 12MM buzzer need bottom sealant, in order to its performance Stability and prevention of magnetic core shedding and other adverse situations occur. Therefore, visual inspection is only a preliminary identification method.
The following is another way to introduce
. Two, multimeter test:
Test with the multimeter resistor Rxl: connect the buzzer'+'pin with the black meter pen, and touch the red meter pen back and forth on the other pin. If the click or click is triggered and the resistance is only 8 (or 16), the passive buzzer is active if it can make a sustained sound and the resistance is more than several hundred Euros.
Three. DC voltage test:
General 12MM passive general voltage is 1.5V, active electromagnetic buzzer general voltage is 1.5, 3.0, 5.0, 9.0, 12V, with DC voltage input corresponding voltage (can be small to large), frequency is about 2.7KHZ, can be directly sounded for active electromagnetic buzzer, not directly sound, need square wave to drive can be loud Passive electromagnetic buzzer.