Learn why ultrasonic generator and transducer matching matters, including frequency, impedance, and

What Are an “Ultrasonic Generator” and a “Transducer”?

In an ultrasonic cleaning system:

• Ultrasonic Generator
The generator is the “heart” of the system. It is responsible for producing high-frequency electrical energy, such as 28 kHz, 40 kHz, or 80 kHz.

• Transducer
The transducer converts electrical energy into mechanical vibration. It is installed at the bottom or side wall of the cleaning tank and transmits ultrasonic energy into the liquid.

Simply put:

• The generator produces energy.

• The transducer converts that energy into vibration.
  
  Both must be electrically matched and mechanically resonant in order to achieve the best cleaning efficiency.

Principle of Energy Transmission

1. The high-frequency circuit inside the generator produces AC voltage, which is transmitted through the cable to the transducer.

2. The piezoelectric ceramic discs (PZT) inside the transducer generate tiny deformation under voltage, forming high-frequency vibration.

3. These vibrations are transmitted through the metal vibrating surface into the liquid, triggering cavitation.

4. Countless microbubbles are generated in the liquid. When the bubbles collapse, they release energy and create the cleaning effect.

Matching Relationship Between the Generator and the Transducer

Function
Generator: Produces high-frequency electrical energy.
Transducer: Converts electrical energy into mechanical vibration.
Key relationship: Mutually dependent.

Frequency
Generator: Fixed-frequency or sweep-frequency output.
Transducer: The resonant frequency must be the same.
Key relationship: Frequency matching.

Impedance
Generator: Electrical output impedance.
Transducer: Equivalent electrical input impedance.
Key relationship: Impedance matching.

Energy
Generator: Provides high-frequency electrical energy output.
Transducer: Transfers energy into the liquid.
Key relationship: Stable energy transmission.

Design Focus
Generator: Stable circuit and precise output.
Transducer: Material structure, heat dissipation, and bonding quality.
Key relationship: Mutual adjustment.

If the generator output frequency does not match the transducer’s resonant frequency, problems such as failure to resonate, energy loss, and transducer overheating may occur, causing a significant drop in cleaning power.

Importance of Matching the Generator and Transducer

1. Frequency Matching

The generator output frequency must match the resonant frequency of the transducer in order to achieve resonance.
If the deviation exceeds ±2 kHz, efficiency will decrease significantly.

2. Impedance Matching

During operation, the transducer generates electrical load changes.
The generator must be able to dynamically adjust the output impedance.
Otherwise, reflected energy may return to the generator, causing reduced efficiency and component overheating.

3. Power Matching

The generator output power must match the quantity and specifications of the transducers.
For example, if a 1200 W generator is connected to too few transducers, each transducer may become overloaded. If too many transducers are connected, output may be insufficient and energy may be dispersed.

What Is the Resonant Frequency of a Transducer?

Resonant Frequency

The resonant frequency refers to the frequency at which the transducer can produce the maximum vibration amplitude with the lowest energy consumption under external excitation.
Simply put, it is the frequency at which the transducer vibrates most easily and operates with the highest efficiency.
For ultrasonic cleaning, this frequency is usually fixed, such as 28 kHz, 40 kHz, 68 kHz, 80 kHz, or 120 kHz.

Key Factors Affecting Resonant Frequency

1. Piezoelectric Ceramic Thickness
The thicker the ceramic disc, the lower the resonant frequency.

2. Metal Vibrating Surface Structure
The material, shape, and thickness of the metal vibrating surface can change the resonance point.

3. Bonding Quality and Temperature
Bonding layer thickness and operating temperature may both cause frequency deviation.

4. Liquid Load Effect
After the transducer is installed on the tank and comes into contact with the liquid, the tank wall and liquid absorb part of the energy, increasing vibration damping. Therefore, the resonant frequency is usually slightly lower than in air, by approximately 0.2–0.5 kHz.

An ultrasonic generator and transducer are like an engine and a transmission.
They must be perfectly matched in order to transfer energy effectively.
The balance of frequency, impedance, and power is the key factor that affects cleaning performance.
YONG JI Enterprise has accumulated many years of design experience, providing complete design support from the generator to the transducer.
We ensure that every piece of equipment operates under optimal resonance conditions and delivers the most stable cleaning efficiency.

© 2026. YONG JI 有限公司

永技企業有限公司

YONG JI Enterprise Co., Ltd.

243新北市泰山區中港西路137-10號

No. 137-10, Zhonggang W. Rd., Taishan Dist., New Taipei City 243079, Taiwan (R.O.C.)

TEL: +886-2-2297-1195

FAX: +886-2-2297-1053