Acoustic magnetic generator.

[synchro1]

@Verpies,


Drop dead you miserable fraud!

[itsu]

My 120W ultrasonic cleaner has 200V_RMS across its piezo element and it can do a lot of damage.

Thanks for all the info.

i finally found some spec's on my transducer:

1. Low heat.
2  thermal stability.
3. Frequency and static capacitance consistency and strong.
4. Resonant impedance is low.
5. The average long life.
6. It can be widely used in a variety of ultrasonic cleaning equipment.
7. High performance: high mechanical Q, vibration and high efficiency
8. high amplitude   

Model Number:                          CH-S42-50x2.6
Resonant Frequency (KHz):                     40 ± 1
Static capacitance (pF):                  8000 ± 10%
Resonant Impedance (O):                        = 20O
Diameter * height:                               50 * 2.6
Power (W):                                                 35w
Insulation resistance (2500V DC):         = 100MO   

It does not specify the broadbandness of it, but the Resonant Frequency (KHz):     40 ± 1 points to a very narrow band.
Not sure if it can be used for around 12KHz.


I got my new ferrite rods (200 * 20 mm) and am trying to clamp them in a way they stick to the transducer.
A new pick up coil was needed as the rods are thicker.

This new coil measured:

Without ferrite:   L=        365 uH
                         R=           4 Ohm
                         Res F = 564 KHz

with this new ferrite rod:  L=          4 mH
                                      R=          4 Ohm
                                      Res F= 197 KHz   

I will fire this up tomorrow.


Regards Itsu

[synchro1]

@Itsu,


Looks like "attikanagy" simply has the transducer glued to the end of the ferrite rod. His video is the first "proof of concept" AMG test I've ever seen. Thanks for that hyper link!

[verpies]

It does not specify the broadbandness of it, but the Resonant Frequency (KHz):     40 ± 1 points to a very narrow band.
Not sure if it can be used for around 12KHz.

The resonant frequency is not the bandwidth of the piezo transducer, it is the frequency at which an unloaded transducer has the lowest impedance.
An unloaded transducer will be the loudest a this frequency (and is most likely to be damaged at it), but it will reproduce lower frequencies, too ...albeit at lower amplitudes. 
When a mass (load) is attached to a piezo its resonance frequency decreases proportionally to this mass - just like it does in a mass-spring* mechanical system.

The frequency response of a piezo is very jagged, see the graph below for a common 3cm diameter piezo disk.
This jagginess is why I don't recommend relying on electrical amplitude measurements for determining the standing wave frequency in the piezo and any loads attached to it.

I got my new ferrite rods (200 * 20 mm) and am trying to clamp them in a way they stick to the transducer.

The literature states, that the pre-loading force pressing on the piezo in rest mode should be 10% of the extension force generated by the flexion of the piezo.  It also recommends some type of glue or gel in the interface gap.
Also, remember that those piezo disks extend flexurally like in Fig.3a and Fig.3b  (somehow most of my students come wrongly convinced that they extend as in Fig.2).


* (the stiffness of the piezo acts as a mechanical spring).

[itsu]

@Itsu,


Looks like "attikanagy" simply has the transducer glued to the end of the ferrite rod. His video is the first "proof of concept" AMG test I've ever seen. Thanks for that hyper link!

Your welcome, perhaps i need to glue my ferrite rods also to the transducer as it is hard to "connect" them any other mechanical way.

Regards Itsu