Amplifiers

The 3 most popular Amplifiers

What is the difference between a buzzer and a speaker?

Buzzers and speakers are both transducers that convert electrical energy into sound. The sound a buzzer produces is a buzzing tone, two-tone tone or a fast/slow tone. Buzzers produce a monotonous sound with little variation in frequency. Buzzers consume relatively little energy and are cheap to produce and are therefore often used in applications to save costs and energy. A speaker reproduces the audio signal that is received with a wide range in frequency and volume, making the sound very clear and crisp. brought. Speakers are often more expensive and consume more energy than a buzzer, so they are mainly used in applications where no compromise can be made on sound quality, such as radios or telephones.

Types of buzzers

Piezo buzzer

This buzzer contains a piezo crystal that changes shape when a voltage is applied. This movement then creates sound. This buzzer can be connected directly to a DC power supply. This has the advantages of high sensitivity, high reliability and low power consumption. The buzzer can emit a good sound at a certain frequency. This kind of buzzer is usually used in security, air conditioning, microwave ovens, printers and electronic toys where there are no requirements about the frequency range of the output. In general, especially in electronic products.

Electromechanical buzzer

This uses a magnet, diaphragm and coil. When there is a voltage, a membrane is pulled towards the magnet. This will also cause a current to flow through the coil, creating a magnetic field. This causes the diaphragm to vibrate, causing a sound to be emitted. Electromechanical buzzers have the advantage that they can create an even stronger sound than a piezo buzzer. This up to above 90db. Other frequencies are also possible because there is a larger housing and therefore a larger sound box.

Active and passive buzzer

An active buzzer will make a sound as soon as there is voltage across it. This is not the case with a passive buzzer that requires a control signal to generate an audio signal.

How do you connect the piezo buzzer?

If the buzzer consists of 2 pins, then we are talking about an active buzzer with its own driver circuit. Only the correct voltage needs to be connected to this. A long pin is usually the plus ''+'' and the short pin is usually the minus ''-''. The buzzer may have wires instead of pins. in that case the red wire is often the plus ''+'' and the black wire the negative ''-''. When the buzzer consists of 3 connecting wires/pins, it is a passive buzzer. In this case you must use a PWM (pulse width modulation) signal. This is a signal consisting of pulses with a certain interval to determine the volume. A PWM signal can be generated with most microcontrollers, but you can also use one PWM module Use to control the active buzzer without a code.

Types of speakers

Electromagnetic speaker

This uses an alternating magnetic field. This principle is hardly used anymore because the sound quality is less good. A membrane is coupled to a permanent magnet. An alternating magnetic field will be created using a coil and an alternating current that contains sound information. Lorentz forces acting on the membrane create a sound.

Electrodynamic speaker

This is the most commonly used speaker. With this speaker we use a constant magnetic field. A current will flow through a coil again. The windings of the coil will experience a force, the Lorentz force. This coil is attached to a membrane. This membrane will cause vibrations due to the Lorentz force on the coil.

Transducers

A transducer is a device that converts energy from one form to another. Sound transducers convert an electrical current into vibration which can be transmitted to a surface to function as a speaker. By mounting the transducer on a table or cabinet, for example, it will amplify the vibration and play the sound like a normal speaker would.

How do I connect a speaker/transducer?

A speaker needs a high-power control signal (several to hundreds of Watts). Since a microcontroller like Arduino can't provide this, you need a amplifier necessary. An amplifier, as the name suggests, will amplify a small control signal so that it can drive a speaker with a certain power and impedance.

What does the resistance value of a speaker mean?

The electrical resistance is expressed in ohms, also known as resistors. The smaller the resistance, the more power can flow through the speaker. If you connect a 4 ohm speaker to an amplifier that can drive 100W at 4 ohms, you get the most out of the amplifier. If you replace the speaker with an 8 ohm version, you will only get half the maximum power / volume.