Ultrasonic bath

Yes, the 555 is switching the relay (on/off).

I don't know what exactly this design is, but it seems you are right. The transformer has three pins. Two of them drive the transducer, and the other one is connected to the mains power. Parallel to the driving coil there is a capacitor. In the first I thought a simpler design. Now, I think the schematic is needed.

On Sat, 16 Aug 2008 05:20:21 +0300, "Yianni" put finger to keyboard and composed:

This URL claims that the design is patented, hence my question:

There is sometimes a patent number on the rating sticker.

The power spec for your cleaner is 35W @ 110V and 50W @ 220V. That seems on a par with the "professional" transducers above.

How about these "buzzer" shaped transducers:

They all have a well defined resonant frequency.

I also wondered about that. I don't have an answer, though.

Yes I am aware of that.

- Franc Zabkar

Your ignorance is wide and deep.

"Buzzers" are, indeed, resonant. In fact, most mechanical systems are resonant. When you combine a mass with a restoring force, you get a resonance.

You are right. Finaly I found a patent number: 01301930.9 . But I found nothing for this patent. May a chinese patent.

Don't trust the specification on chinese machines -especialy the inexpensive ones-... The specifications says "power", I think it's the power consumption!! On the other hand, it won't be surprise to be 20W...

I was thinking another aspect. At the first post, I said a 50% frequency increase, in my mind I have the possibility of 100% increase. Even if the "transducer" resonate to a frequency, it would resonate to the double frequency too. With "transducer" I mean the transducer alone or the combination of transducer/tank.

I will try to find the schematic anyway!

The photos are small, I can't understand. The buzzer/transducer of the ultrasonic is: diametre 40mm (1.5"), thickness 4mm (0.15"). The "normal" transducers are about 1000g weight, the specific I suppose about 25g.

On Sat, 16 Aug 2008 19:20:00 +0300, "Yianni" put finger to keyboard and composed:

I found this URL for a "Model 2800: Miniature Ultrasonic Cleaner":

It makes the following certification claims:

Approval & Patent? - ETL approval of USA(No.3012617) - CE approval of EU(No of LVD:H20211 S; No. of EMC:h20175) - GS approval of Germany(No EG0203104) - Our patent No is:01301930.9

I tried searching for "Codyson" here ...

... and found two appliances, but no useful data. :-(

This appears to be the PRC IPO database ...

... but my searches produced nothing.

How much power do you think a "buzzer" dissipates? ;-|

If the transducer is not consuming most of the power, then what is? Do you think it is feasible for the appliance to consume 50W (or 20W) but only deliver a small fraction of that to the transducer?

It makes no sense to say that a transducer can "resonate" at twice its resonant frequency (unless you are talking about overtones maybe ???). I'm guessing that the cleaner's circuit automatically oscillates at the transducer's resonant frequency, ie the external components aren't that critical. I suspect that if you were to replace the transducer with a higher frequency type, the new transducer would oscillate at its own resonant frequency, not 42kHz. You may need to optimise some components, though, to ensure that the transducer looks like a pure resistance. The frequency characteristics of the ferrite toroid would need to be considered as well.

- Franc Zabkar

I may need a single 22V10-10 or -15 programmed. I thought my PAL programmer was working but the burnt PAL behaves strangely in a way that suggests it may have internal incorrect logic. It also doesn't pass the programmer's test wiht respect to the test vectors (but I'm not sure that this ever really worked properly).

I'll pay for the PAL or send a raw one and the .JED file to anyone who might volunteer. :)

Or, if someone has a working programmer they'd like to sell.....

Thanks!

-- sam | Sci.Electronics.Repair FAQ:

Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs.

On 16 Aug 2008 21:09:34 -0400, snipped-for-privacy@seas.upenn.edu (Samuel M. Goldwasser) put finger to keyboard and composed:

I have a Sunshine Expro-60 that has that particular PLD in its device list. However, I'm in Australia.

- Franc Zabkar

Well, if you could email the programmed part... :)

Actually, I think I found a problem in the logic so this may be a non-issue. Tow pins swapped. :( It was my lack of confidence in the programmed more than anything. It's an INLAB28, 20 years old, and I know there were always problems with CUPL and the programmer not using the same squence to do the test vectors. but being 20 years old, my memory is probably more fuzzy than that of the programmer!

Thanks!

-- sam | Sci.Electronics.Repair FAQ:

Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs.

On Sun, 17 Aug 2008 22:26:53 +0300, "Yianni" put finger to keyboard and composed:

Look at it another way. Why would you need a 7 amp relay to supply power to a "buzzer"? Why would you need such a large heatsink and two high current (?) transistors?

I suggest you buy something like this ...

... and measure the power consumption for yourself.

I had another look at the following patent. It suggests that a simple change to your circuit may enable your transducer to resonate at the first overtone (see Fig 3 of the PDF file). It also confirms that the resonant frequency is dependent on the mass of water.

OSCILLATOR CIRCUIT FOR AN ULTRASONIC CLEANER

The author states that "since the piezoelectric disc is closely coupled to the tank and the water load, the water depth in the tank effects the power transferred to the water and the resonant frequency of the transducer".

"On all ultrasonic cleaning systems, some means must be employed to control the frequency at which the generator drives the transducer. If the generator is made to operate at a fixed frequency, poor performance will be encountered, since it is generally not possible to select one frequency which will always provide optimum operating conditions."

"In the case of an ultrasonic generator, one is concerned with the behaviour of a piezoelectric transducer at the fundamental and perhaps the lower order overtone frequencies."

This part looks very interesting:

==================================================================== The preference the circuit shows in operating in the vicinity of some initially selected frequency is also desirable in suppressing tendencies to run at overtone frequencies. In some circumstances, however, this effect might not be great enough to completely prevent operation at the overtone. For instance, if the series resonant impedance of the fundamental frequency is slightly greater than at the first overtone, the circuit preference for lower impedance could take precedence and result in operation at the overtone were the shunt capacitor 86 not employed.

Since the capacitor 86 is connected across the feedback transformer primary, its capacitive reactance lowers the impedance to overtone frequencies. This results in a lower primary voltage or, more directly, an increase in core saturation time. Thus, any tendencies to run an overtone are adequately suppressed, forcing the circuit to run at the fundamental.

In the example given, it is desirable to operate at the fundamental frequency. Nevertheless, if operation at an overtone is desired, this may be accomplished by suitable selection of circuit elements and constants, and the principles of the invention may be employed to enhance operation at the preferred overtone. ====================================================================

- Franc Zabkar

This thread sure has a lot of "fuss" over something that can be EASILY measured. Stick a signal generator and scope (or voltmeter) on it. That'll tell you what you can expect.

Hello Franc,

These info are useful and they explain to me much about ultrasonics. Now, all explained!!! I can understand that transducer/tank/water can affect the resonant frequency. That's why the noise is different when the tank is full or half empty; some times it works much away from the resonate frequency because it makes louder noise (I feel it). It seems, it works in a steady frequency.

I understand that needs the schematic someone to know how to increase the frequency. In the first I thought it would be easy someone to recognize the design. Seeing that the final transformer has only 3 pins, and the fact that the mains supply direct the transducer (as you said amplitude modulated) I understand the design should be more complicated. After all that, I closed the ultrasonic leaving it working the usual way!