Electronic musical instruments · audio · video equipment

This page introduces examples of AC adapter development for electronic musical instruments, acoustic equipment, and imaging equipment. At UNIFIVE, we have obtained various achievements and high evaluations including leading companies such as noise countermeasure of AC adapter and safety standard.correspondence.

Electronic musical instruments are instruments that produce low frequency waveform signals by electronic circuits. The environment to be used is used in various places such as general homes, educational sites such as schools, professional musicians, etc.


With the electronic circuit, you can control the pitch, volume, and timbre, which are elements of sound. As a method of obtaining a timbre, there are a subtraction method of obtaining a timbre by filtering a periodic pulse train, an addition method of synthesizing harmonics by a sine wave like a organ, a modulation method typified by an FM sound source, a recorded waveform There are several methods, such as PCM method to store in the memory everything like pitch. In the past, hardware synthesizers that used dedicated custom ICs as sound sources were mainstream, but in recent years software and synthesizers are on the rise.


Origin and history, according to one theory, started with the invention of Denis D'Or using the electromagnet by Prokop · Divish of 1748, and thereafter the electronic organ, the electric guitar, the analog synthesizer, the digital synthesizer etc. Electric musical instruments are now in active age to appear in various places and scenes, such as the stage, educational sites such as families and schools, public places such as stations, and so on.


It is developed in a wide range of electronic musical instruments, various fields.

  •    Electronic organ
  •    Electone
  •    Electronic Piano
  •    Drum machine
  •    keyboard
  •    Amplifier
  •    Guitar synthesizer
  •    EWI

About the AC adapter used for electronic musical instruments

About safety standard

Basically, IEC / EN 60065 of the technical standard stipulated by the IEC stipulates that the designated equipment falls under. When acquiring the authentication itself, both linear and switching type power supplies apply.

About the difference point of safety application with communication equipment IEC / EC 60950

In the case of application and design for safety regulation, most of the part of the communication equipment can be commonly used, but as a reference example, the difference points are listed below.

① LPS request

    (Communication 60950): Evaluation measurement is essential
    (Acoustics 60065): No measurement required

② X electrolytic capacitor

    (Communication 60950): Residual voltage <37% is required after one second disconnection
    (Acoustics 60065): After 2 seconds of breakdown, residual voltage Peak 35.0V or 60 V dc (judgment criteria with 60 V dc)

③ Temperate environment

    Leakage current: (communication 60950) 0.25 mA; (sound 60065) 0.5 mA request.

④ Tropical environment operating temperature

    (Communication 60950) 35 ° C (Subtract component specification 10K) (Acoustic 60065) 45 ° C (Subtract component specification 10K)

⑤ About oil test (Softening Test)

This test is required only by the acoustic standard (UL).


Test reference method:

The designated part is put in oil, the temperature of the oil is started from 100 ° C, raising the temperature by 50 ° C in every hour, and it becomes the verification test up to 175 ° C.

The temperature of a flat needle of 1 square millimeter penetrates 1 mm into the material of a specific Load and Heating rate.Vicat softening temperature is used to compare thermal softening characteristics of different materials.

Testing Methods

There are four different methods used for this test.

MethodLoad (N)Heating Rate (°C/hr)
A50 10 50
B50 50 50
A120 10 120
B120 50 120

Test results, case structure requirements:
For the case material, the thickness of the dent is <0.1 mm.

About product introduction and development cases

* We will give reference examples of some customers dealing with our products.

We received a request from a certain major manufacturer S to develop an AC adapter to be used for radio products.


Since the case of the AC adapter which was developed at the beginning, since the resin material of the case was PC material, we got a situation where it became NG as it applied to the application for the application for the ruling application. The test that turned out to be an oil test.


The cause was not understood, and even if it changed to various materials, it did not show the effect more than expected, and analyzed with customers, it changed only between the metal AC pins to the connected resin material, It was clear that it could be cleared without changing the PC resin material adhered to it, and it was possible to solve it with the customer. Explanation Reference drawing, please refer as follows.


The view based on our experience is that it is difficult to clear it unless it is a molded resin material with two different materials.


In this case, the knowledge we got, when choosing the same material of resin material, the indentation appears immediately after receiving heat, and on the contrary, another type(Either from the case material, the material is soft or harder)when using the material of one, the synergistic effect that one material pulls to the opposite side in the direction which is recessed with the feeling like another saucer after receiving heat is obtained.


The above example is based on our experience. So, in fact, there are various ways to respond. In the above example of our company, we would be pleased if you could refer to our customers who are in need of even a little.


There are some details on this example, but if you have any problems with anything, please do not hesitate to ask us. Our strengths of development and also good correspondence about safety standards, thanks to you we have received great trust from our customers.

You can get the product catalog in PDF.

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Since 1989, UNIFIVE has maintained the quality of their AC power adapters and switching power supplies through rigorous quality controls.

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