Which One Should You Actually Use：Electromagnetic Buzzer vs Piezo Buzzer

1.Introduction
2.Why Buzzer Not Working Is So Common?
3.What is the Electromagnetic Buzzer?
4.Electromagnetic Buzzer Key characteristics
5.The Real Comparison
6.Practical Selection Advice
7.FAQ
8.Conclusion

Introduction
If you've ever gone looking for buzzer in order to use with your electronic project, you've seen the same weary advice being given to you over and over again: "Just use a piezo, it's better."
That is not wrong, but it is also not always the truth. The reality is that another considerable number of buzzer related problems arise because of a lack of understanding of how different buzzers do really work. This blog will introduce you the difference bewteen buzzer.

Why Buzzler Not Working Is So Common?
One of the most common issues involves one of the simplest problems-the buzzer is wired up right, but it's too quiet, it's no sound at all. In most cases, it is not the MCU, and also not code. It's one of these:
1. Wrong type of buzzer (active/ passive)
2. Lack of amount of drive voltage or current to drive
3. False expectation of the sound pressure level (SPL)
Understanding the difference between the electromagnetic buzzer and the piezo buzzer will typically solve 80% of these issues. Before we get into the comparison, it's important to understand what makes these two types fundamentally different, in terms of the way that they make sound.

What is the Electromagnetic Buzzer?
An electromagnetic (magnetic) buzzer consists of three main parts: a coil, a magnetic field and a mechanical movable diaphragm. When the current passes through the coil it will create a magnetic field that causes the diaphragm to move back and forth physically generating sound waves.
The working principle is similar to that of a small speaker. The coil acts as an electromagnet and attracts or repels a magnetic armature connected with the diaphragm. This is what causes the mechanical motion in hearing sound that you can hear from.

Electromagnetic Buzzer Key characteristics
1. Strong sound at low frequencies, since the diaphragm is a mechanical motion, the electromagnetic buzzers can generate low-resonance sounds with deep and strong resonance that are quite capable of carrying in a noisy environment.
2. Noticeable mechanical vibration, you can often feel the buzzer vibrating as it's operating, which can be useful for mounting considerations.
3. Increased current usage, more power will be required to run the coil than voltage based actuation. Normal current draw is 20mA to 100s of mA depending on the model.
4. Sound depends greatly on drive conditions, frequency, duty cycle and the current all have an effect on the output volume and tone quality.
This makes buzzers which are electromagnetic well suited for alarms in security systems; warning indications in a machinery; industrial equipment; appliance user interfaces where sound must retain itself over ambient sounds
One very important note to make: electromagnetic buzzers are available in both "active" and "passive" forms. Active buzzers come with inbuilt oscillator circuits and will beep upon the application of DC voltage. Passive buzzers need a square wave signal of the desired frequency from outside.

The Real Comparison
Now let's come to these two technologies next to each other with some practical details, the ones you care about in real designs:
1. Drive method:
Electromagnetic is the one current driven. You have to pump enough current through the coil in order to move the diaphragm.
Piezo: voltage-driven. The ceramic changes with changes in voltage, and draws very little current.
2. Power consumption:
Electromagnetic: Larger, typically 30-100mA @ operating voltage
Piezo: Very low/ under 10mA/ in efficient designs, may only be microamps.
3. Sound character:
Electromagnetic: "Full" and mechanical sounding and many times called warmer or more natural. Good bass response.
Piezo: Sharp and more tonal, more of an "electronic" quality. Unpleasant-sounding if not well driven.
4. Frequency flexibility:
Electromagnetic: Better at low frequencies 100Hz - 2kHz, can vary tone more easily.
Piezo: Maximum performance near resonance (usually 2-4kHz), significant drop off at volume off resonance.
5. Lifetime:
Electromagnetic limited by mechanical wearing of the diaphragm and coil. Capital life (measured in million) of the construction statute.
Piezo: Very long with ratings common in the tens of millions of cycles with low levels of degradation.
6. MCU direct drive:
Electromagnetic: Often no. Most require a transistor or an n-channel.
Piezo: Often yes. Many are possible, however, being driven directly from MCU chips, from their General Purpose I/O pins if voltage levels match.
There is another potential confusion in terms, "active" and "passive." This is about whether or not the buzzer has an internal oscillator, and not whether it uses an electromagnetic or a piezo technology. You can have active electromagnetic buzzers, passive electromagnetic buzzers, active piezo buzzers and passive piezo buzzers.

Practical Selection Advice
If you select an electromagnetic buzzer then:
1. You need strong, noticeable sounding sound which cuts through the ambient noise
2. Power consumption is not so limited (mains powered OR big battery systems)
3. The device is used in noisy industrial/commercial environments
4. You want better deep, more mechanical sounding tones
5. You require loose frequency response to suit musical notes or different alarming
You can choose a piezo buzzer if:
1. Power efficiency is important (battery life is important)
2. You are looking for maximum operational lifetime with minimum maintenance
3. Your system can drive at the correct resounding frequency
4. Higher frequency tones (2-4kHz) for your application
5. You have a lack of space issues (piezo buzzers can be very thin)

FAQ
Q1: Why is my buzzer very quiet?
A1: Most frequently the drive voltage or the current is too small or the type of buzzer is not suitable for the method of driving. Check to see if you have active or passive, check to see if you have a drive circuit that will provide enough current for electromagnetic types and if you are pacing passive buzzers at the rated frequency.
Q2: Can I drive an electromagnetic buzzer from an MCU?
A2: Usually no. Most MCU gpio pins will only be capable of sourcing 10-25mA while electromagnetic buzzers will typically require 30mA or greater. You'll need a transistor, a MOS- FET or specific driver IC. On the other hand, active piezo buzzers may often be driven directly.
Q3: Is Piezo always better than Electro-Magnetic?
A3: No. "Better" is entirely dependent upon your sound requirement, power budget and application environment. Electromagnetic buzzers sound fuller and in noisy environments also function better. Piezo buzzers win in the efficiency department, as well as in the lifetime department. There is not one of these universally better.
Q4: Why are some buzzers not so good?
A4: As a result they are often driven off-resonance or at incorrect frequencies. Piezo buzzer in particular requires driving close to its resonant frequency to achieve a good sound. Also square waves with very fast rise times can generate harmonic distortion which sounds bad. 

Conclusion
Pick your buzzer according to actual requirements: sound quality, power budget, working environment and drive capability, not as per generic buzzword guidance received from online world. Understanding the working of each one of the technologies will enable you to avoid the most typical pitfalls, and get sound output reliably in your designs.

Looking for the right buzzer solution? Contact our engineering team today for advice and a quote.