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The working principle of ultrasonic transducer

Update time:2020-05-23 11:19:40Clicks:2584
The ultrasonic transducer is damp. In general, Megabyte meter is used to check the plug connected with the transducer. The insulation resistance value between the positive and negative terminals of the transducer can be determined.
Ultrasonic cleaner transducer often appear problems

1) The ultrasonic transducer is damp. In general, Megabyte meter is used to check the plug connected with the transducer. The insulation resistance value between the positive and negative terminals of the transducer can be determined. General requirements of insulation resistance greater than 30 megohm. If this insulation resistance is not achieved, it is likely that the transducer will become damp. The maintenance method is to put the transducer as a whole (excluding the plastic shell) into the oven and set it at about 100℃, dry it for three hours or use the hair dryer to remove the moisture until the resistance is normal.

2) The transducer vibrator burns and the ceramic material breaks. Maintenance can be combined with the naked eye and megohm meter inspection. Generally, as an emergency treatment measure, the individual damaged transducer can be disconnected, which will not affect the normal use of other transducers.

3) The transducer is degummed. We know that most manufacturers use a sticky way to fix the transducer, but the long-term use of the ultrasonic cleaning machine due to vibration will appear degumming phenomenon. Some manufacturers also use the method of cementing and screw fastening, generally there will be no degumming, because of the action of the screw, the oscillator will not fall from the vibration surface after degumming, the general judgment method is to use the hand to shake the tail of the oscillator, carefully observe the glue on the vibration surface to make a judgment.

Generally, the output power of the ultrasonic power supply is normal after the oscillator is degumed. However, due to the poor connection between the oscillator and the vibration surface, the vibration effect of the vibration surface is not good. After a long time, due to the energy cannot be released, it is likely to burn out the oscillator. It is troublesome for the user to repair the vibrator. In general, it can only be returned to the manufacturer for maintenance. The most effective way to avoid degumming is to pay attention not to hit the vibration surface in normal use.

4) Vibration surface perforation. In general, the vibration surface may be perforated after the ultrasonic transducer is used at full load for several years, which is due to the long length of the stainless steel plate on the vibration surface

Due to fatigue caused by high frequency vibration, the vibration surface perforation indicates that the service life of the transducer has arrived, and the maintenance can only be replaced generally.

Ultrasonic cleaner generator often appear problems

1) Turn on the power switch of the ultrasonic cleaner, and the indicator light is not on. In this case, the maintenance must check whether the power switch is in good condition and whether the leakage switch is closed. If the switch is in good condition, then check whether the fuse is overloaded and fuse is broken.

2) When the power switch is turned on, the indicator light is on, but there is no ultrasonic output. This kind of circumstance is more complex, when maintenance, check the connection plug of transducer and ultrasonic power board whether to have loosen first, check whether fuse is blown next. If everything is normal, it may be the internal fault of the ultrasonic power generator. Use the multimeter to make the open power line and the fire line. After the generator fault is eliminated, check whether the ultrasonic transducer is burnt out and whether it needs to be replaced.

3) The dc fuse of the ultrasonic cleaner is blown. It may be the burn out of the rectifier bridge stack or the power tube, or the aging of the transducer and the instability of the current, which may cause the failure of the power generator. Take care when repairing.

4) After turning on the power switch of the ultrasonic cleaner, the machine has ultrasonic output, but the cleaning effect is not as good as before. This situation is mostly caused by improper use, for example, the cleaning liquid level in the cleaning tank is improper, too high or too low; Ultrasonic frequency coordination is not adjusted; The liquid temperature in the cleaning tank is too high or too low; Improper use of cleaning liquid or insufficient dosage. Of course, it is not ruled out that most of the ultrasonic energy cannot be transferred to the cleaning fluid after the transducer is degummed-this situation should be sent back to the manufacturer in time for maintenance, so as not to burn out the oscillator.

Of course, the above is just some basic maintenance ideas of ultrasonic cleaning machine, in the actual maintenance operation also need to be rich in professional knowledge and practical experience, ultrasonic cleaning machine now the general service life can be used basically five to eight years above.

The working principle of ultrasonic transducer

(1) Ultrasonic transducer: a device that can convert high-frequency electrical energy into mechanical energy, generally including magnetostrictive type and piezoelectric ceramic type. The power output to the ultrasonic generator, and then to the ultrasonic transducer, generally through the ultrasonic out of the receiving device can produce ultrasonic waves.

(2) The composition of the ultrasonic transducer: including the shell, the matching layer, namely the sound window, the transducer of piezoelectric ceramic disc, the backing, and the lead cable. The characteristics of the ultrasonic transducer lie in that it also includes the array receiver, which is composed of lead cable, the transducer, the metal ring and the rubber washer.

(3) The principle and function of ultrasonic transducer, ultrasonic transducer is resonant Yu Chaosheng frequency of piezoelectric ceramics, the material of the piezoelectric effect converts electrical signals into mechanical vibration. The ultrasonic transducer is an energy conversion device, its function is to convert the input electric power to mechanical power (ultrasonic) passed out again, part of the surface it consumes very little power. Types of ultrasonic transducers: piezoelectric transducers, sandwich transducers, cylindrical transducers, inverted horn transducers and so on.

Overview of 40kHZ ultrasonic transmitting/receiving circuits

40kHZ ultrasonic transmitting circuit (1)

As one of the 40kHZ ultrasonic transmitting circuits, the output of the F1~F3 three-door oscillator at F3 is 40kHZ square wave. The working frequency is mainly determined by C1, R1 and RP. The frequency is adjusted by RP adjustable resistance. One end of the output excitation transducer t40-16 of F3 and the inverter F4, F4 outputs the other end of the excitation transducer t40-16, therefore, adding F4 can double the excitation voltage. Capacitance C3 and C2 balance the output of F3 and F4, making the waveform stable. In the circuit, four of the six CC4069 inverters are used for the inverters F1~F4, and the remaining two are not used (the input end should be connected to the ground). A 9V laminated battery is used for power supply. Should the output frequency of measurement F3 be 40kHZ? 2kHZ, otherwise adjust RP. The transmitted ultrasonic signal is greater than 8m.

40kHZ ultrasonic transmitting circuit (2)

In the 40kHZ ultrasonic transmitting circuit ii, the transistor VT1 and VT2 form a strong feedback frequency stabilizing oscillator. The oscillation frequency is equal to the resonance frequency of the ultrasonic transducer t40-16. T40-16 is a feedback coupling element and an output transducer for the circuit. The oscillating waveform at both ends of t40-16 is similar to a square wave, and the voltage amplitude is close to the supply voltage. S is the power switch. By pressing S, the t40-16 can be driven to emit a series of 40kHZ ultrasonic signals. The working voltage of the circuit is 9V and the working current is about 25mA. The transmitted ultrasonic signal is greater than 8m. The circuit works without debugging.

40kHZ ultrasonic transmitting circuit (3)

40kHZ ultrasonic transmitting circuit 3, composed of VT1, VT2 positive feedback feedback oscillator. The oscillation frequency of the circuit is determined by the t40-16 of the feedback element, whose resonant frequency is 40kHZ? 2 KHZ. The frequency stability is good, without any adjustment, and t40-16 is used as transducer to send out 40kHZ ultrasonic signal. The inductance L1 and capacitance C2 are tuned at 40kHZ. This circuit is suitable for wide voltage (3~12V), and the frequency is unchanged. The inductance is fixed and the inductance is 5.1mh. The working current of the machine is about 25mA. The transmitted ultrasonic signal is greater than 8m.

40kHZ ultrasonic transmitting circuit (4)

40kHZ ultrasonic transmitting circuit no.4, which is mainly performed by the four-gate circuit CC4011 to oscillate and drive, and controls the receiver by emitting ultrasonic waves from the ultrasonic transducer t40-16. Among them, gate YF1 and gate YF2 constitute a controllable oscillator. When S is pressed, the oscillator vibrates and RP is adjusted to change the oscillation frequency, which should be 40kHZ. The oscillation signal controls the work of the differential phase driver composed of YF4 and YF3 respectively. When YF3 outputs high power, YF4 will output low level. When YF3 output is low, YF4 output is high. This level controls the t40-16 transducer to emit 40kHZ ultrasonic waves. In the circuit, YF1~YF4 adopts high-speed CMOS circuit 74HC00 four-gate and non-gate circuit, which is characterized by large output drive current (more than 15mA) and high efficiency. The working voltage of the circuit is 9V, the working current is more than 35mA, and the ultrasonic signal is more than 10m.

40kHZ ultrasonic transmitting circuit (5)

40kHZ ultrasonic emission circuit 5, composed of a 40kHZ multivibrator circuit with LM555 hour base circuit and peripheral elements, can change the oscillation frequency by adjusting the resistor RP resistance value. The ultrasonic transducer t40-16 is driven by the third pin output of LM555 to emit ultrasonic signals. The circuit is simple and easy to make. Circuit operating voltage 9V, operating current 40~50mA. The transmitted ultrasonic signal is greater than 8m. LM555 can be directly replaced by NE555 with the same effect.


Bistable ultrasonic receiver circuit

Because the monostable receiver has no memory function, it cannot be used in the opening and closing of household electrical appliances. Is a bistable ultrasonic receiver circuit, but the execution circuit is different.

Circuit, composed of VT5, VT6 and related auxiliary components bistable circuit, each time when VT4 conduction (a transmitter), trigger signal to the bistable circuit via C7, C8 into a trigger pulse, VT5, flip a VT6 state, when VT6 from cut-off condition into conducting state, VD5 cut-off, VT7 cut-off, relay K release; When another trigger signal comes, VT6 will change from on-off to cut-off state, VD5 on-off, VT7 on-off, relay K on-off... Due to the addition of bistable circuit, it has become a reality for remote control of electric appliances such as electric lamp, electric fan and TV. During debugging, after a quick short circuit with a wire between point a and +6V(power supply), the relay shall be released. After a short circuit, the relay shall be released. If there is no response from the relay, please check the welding quality and component parameters of the bistable circuit components. Usually it will succeed next time.

Monostable ultrasonic receiver circuit

Monostable type ultrasonic receiver circuit principle diagram, the resonance frequency of 40 KHZ ultrasonic transducer R40-16, after R40-16 frequency selective, 40 KHZ outside interference signal attenuation, only a resonance in 40 KHZ (transmitter) into useful signal VT1 ~ VT3 qualcomm amplifier amplification of the C5, dc component VD1 detection, control of VT4, VT5 electronic switch drive relay K job. Since this circuit only amplifies single-channel signal, when the transmitter transmits ultrasonic signal once, the relay of the receiver will absorb once (the absorbing time is the same as that of the transmitter), and there is no memory retention function. It can be used for wireless remote camera shutter control, children's toy control, curtain control, etc. VT1 beta in the circuit? 200, VT2 beta? 150, other components are customized. The circuit works without debugging. If the sensitivity and anti-interference are not enough, it can check whether the margin of the transistor's margin value and capacitance C4 is too big. According to the actual measurement, with the corresponding transmitter, the remote control distance can reach more than 8m. There is no direction in the room because the walls reflect. The working voltage of the circuit is 3V, and the static current is less than 10mA.

(Edit:admin)