Building the Ultrasonic Antifouling Kit from Jaycar

[Norman_E]

If you use epoxy that sets hard the energy from the transducer could shatter it over time. Interestingly, I had a chat with one of the commercial unit suppliers at LIBS, and he said that their transducers are encapsulated inside an outer casing made of glass reinforced plastic, as they think that the transducer will eventually shatter a plastic pipe fitting as used in the Jaycar kit. Time will tell, but if it does shatter I will simply use epoxy adhesive to stick the transducers to the hull.

 

[nigelmercier]

But do you agree, harder epoxy resin would also electrically protect, but help the ultrasonic energy to better penetrate the hull??

I don't think it makes any difference, as the transducer is almost in contact with the hull. I've got a similar transducer in an ultrasonic cleaner, it just sits on a bit of flimsy plastic.

 

[affinite]

I had to laugh

Looks like we have someone from Jaycar on the forum now, great stuff. Perhaps he can sort out the nonsense that causes the pack of epoxy to take the weight of the kit into the next delivery band ...

Just received my kit(s) and quickly built one of them.

So how do I know the bloomin thing's working ?
I have slight hearing loss at the top end so cant hear these clicks that have been mentioned. I also dont have a sillyscope, but Id like to know its working before flying it out to the boat.

The thing that made me laugh was following Nigels comments about the carriage costs for the epoxy, I looked at mine and saw "made in Ashby De la Zouch". 40 miles round trip from my house or 20,544 miles via Jaycar

 

[Stefanb104]

Mounting the transducer

I've been thinking about this part of the assembly. Jay car has made a great job of putting the kit together and pretty good with the instructions. The mounting is a variable out of Jaycar's control. Obviously we all want to get the maximum value out of the unit and the best way is to get the transducer mounted directly on to a solid part of the hull where the vibrations will resonate through the entire length of the hull. Any interface between the transducer and the hull's outer laminate absorbs energy and reduces the effectiveness of the anti fouling.
The question to be answered is, what is the life expectancy of the transducer. I reckon it is probably at least 15 years. So mounting the unit directly onto a prepared area on the inside of the hull outer shell using the same material l as the hull I.e. GRP epoxy resin will give the best conduction. Sliding a sleeve made from thick flexible pipe over the unit and back filling to pot it will use minimal space and provide a vibration resistant outer jacket. Fit and forget for at least 15 years, and then cut it out and replace it if it fails.

 

[Plamen]

Basically, you are right.
Permanent GRP “pouring-in-place” would be the best for a flat & easy accessible mounting location.
On a place with significant declination, or hard-to-access, could get difficult.

 

[Plamen]

Just received my kit(s) and quickly built one of them.

So how do I know the bloomin thing's working ?....

Put it 1/3 in water and you can observe the surface vibrating.
Strong light source to the water surface, play changing the light angle,
and you can see decent waves.

 

[nigelmercier]

The question to be answered is, what is the life expectancy of the transducer. I reckon it is probably at least 15 years...

I wouldn't like to put a value on the MTBF, but I do know that the specification of the driver is well within the ratings for the device. Even if it is mounted directly (as I intend to do) there should be no problem prising it off.

 

[Stefanb104]

Mounting the transducer

Well, so far it seems that mounting the transducer directly is becoming favourite.
The only piece of the jigsaw that is missing is the manufacturer's spec on the expected service life of the unit.
Can anyone track that info down? I wouldn't know where to start.

 

[nigelmercier]

The only piece of the jigsaw that is missing is the manufacturer's spec on the expected service life of the unit...

I've emailed the manufacturer.

 

[affinite]

Spectrum Analyzer

I thought the members of the JUAF club might like this little piece of Freeware at

http://www.sillanumsoft.org/

Its a PC based spectrum anaylzer. I havent really got much of a clue how to use it but when installed and hooked up to a simple microphone is does show all sorts of interesting waveforms comming from the transducer.
I was suprised to see no signals above 20kHz but perhaps its because I was using a very basic/cheap microphone and 40Khz is above its operating range.

Anyway, seeing the waveform dancing around on my "scope" along with my ringing ears are good enough for me to assume Ive built the kit(s) correctly.
Just hope the barnies agree

 

[nigelmercier]

I was suprised to see no signals above 20kHz but perhaps its because I was using a very basic/cheap microphone and 40Khz is above its operating range...

The other problem is that the duration of each pulse is very short, only 1000 cycles, so difficult for the analyser to lock on.

I've been thinking of building some sort of device for testing these units, perhaps one that shifts the frequencies into the audible range, like a bat detector.

I heard back from the manufacturer of the transducers, not good news: expected life is a couple of years. On the other hand, I'm pretty sure the units are being driven at well below their maximum.

 

[Stefanb104]

2 years!

Hi Nigel

Thanks for getting the info on the transducer.
2 years seems to be pessimistic even from a manufacturer. I wonder if it is worth pursuing by giving the regime that it will work under and seeing what their estimates might be. otherwise the idea of fixing directly to the hull becomes impractical. What did they design the unit to do?
I wonder also what the cost of a higher spec transducer would be to replace this one that would give a longer working life. The big problem now is that it would be messing around with Jaycar's initial design and I'm sure that the interrelationship between components is complex and has a long term significance.
To summarise, I guess we are all looking for a "fit and forget" for at least 10 years, but how do we achieve this? Again it may be that Jaycar already has the stats for this and could give an opinion "without prejudice" so that we can all make an informed decision for ourselves.

It seems that we are all spending al lot of time on a simple fairly cheap piece of kit, but if it works.........oh the saving in time and money and effort is enormous.

 

[wizard]

Hi Nigel

Thanks for getting the info on the transducer.
2 years seems to be pessimistic even from a manufacturer. I wonder if it is worth pursuing by giving the regime that it will work under and seeing what their estimates might be. otherwise the idea of fixing directly to the hull becomes impractical. What did they design the unit to do?
I wonder also what the cost of a higher spec transducer would be to replace this one that would give a longer working life. The big problem now is that it would be messing around with Jaycar's initial design and I'm sure that the interrelationship between components is complex and has a long term significance.
To summarise, I guess we are all looking for a "fit and forget" for at least 10 years, but how do we achieve this? Again it may be that Jaycar already has the stats for this and could give an opinion "without prejudice" so that we can all make an informed decision for ourselves.

It seems that we are all spending al lot of time on a simple fairly cheap piece of kit, but if it works.........oh the saving in time and money and effort is enormous.

Perhaps an email through Jaycar to the circuit designer might be in order on this to get his actual design criteria.

I sincerely doubt he had approx 2 years in mind.

 

[Stefanb104]

Transducer life

Do we have a Jaycar rep watching this thread?

 

[OzOns]

Hi,

Any news ? I'am following this thread with a big interest. I also builded one.

The boat first 30 is moored in Venice (Italia). Since 1st of may the device is in fonction (hope so). The hull is realy dirty. Next report in July after the cleaning in water. Hope the cleanning operation will be easier than without Jaycar device.

Llooking forward reading news about our experience.

 

[xiaoneitie]

Now a question for the electronics wizards here. Should I make sure that components like resistors and capacitors stand a bit clear of the PCB, if so, by how much?

 

[OzOns]

no clearence. Better for mecanical reason (vibration)

In fact not very important.

 

[mmascellani1]

hi everybody.
new user from italy.
just saw some articles on the web and decided to try....to do it myself.

so, bought 2 issues at silicon chip regarding intructions, but...i couldn't find pic programming software.

so my request is: do anybody has this sw?

 

[Interlude]

Jaycar had a stand at the Sydney boat show, so I asked them about the 2 year life question. They said there was a 2 year guarantee, and they expected much more than 2 year life from the transducer and the electronics. Time will tell!

 

[sailorbaz]

Just bought the kit from a Jaycar shop in Sydney. I'm hoping it will stop the barnies colonizing my prop!
Should the transducer be below the waterline? Or doesn't it matter?
Sailorbaz