Building the Ultrasonic Antifouling Kit from Jaycar

[elton]

Sorry for thread drift,

[Norman_E]

Do the instructions tell you to adjust it before you insert the ICs? I wonder why it has an adjustment rather than using a fixed 5V regulator.

Anyway I would adjust it using battery power. It's never going to see an exact 12V supply in real life.

Yes, you adjust it with one of the IC and the fuse removed. The reason for the adjustment is that it sets the low voltage shut down threshhold. I have just re-read the technical descrition of the electonics, and the relevant piece reads: The 5V supply rail for IC2 is provided by a TL499A regulator, IC1. ..... Its output voltage is trimmed to exactly 5V using trimpot VR1. This is done to set the low voltage shutdown threshold.

There is a description before that of how the input voltage is split by a voltage divider consisting of 10K and 20K ohm resistors and the resulting voltage filtered and monitored at IC2, converted to a digital value and compared to a reference value in the software.
I infer from the above that regardless of input voltage IC1 will maintain 5V at IC2 and that the constant 5V input from IC1 is used by the software as a reference value and has to be accurately set in order that the software shuts the system down at the correct 11.5V input level and restarts it at 12V.

I may be wrong but the way to test the theory will be to try setting the 5V with a fully charged battery, and then sustituting a partially discharged one and testing to see if the output at the test pins is stll 5V. I have two garden tractors with batteries to use.

[Norman_E]

I have now done the voltage setting and it is as I suspected. In the end I remembered that we have two jump starters in the garage, and on checking them I found one to be reasonably charged at 12.9 volts, and the older one down to 11.11 volts. I connected the good one as shown in the photo and adjusted the trimpot, bringing the recorded voltage up from 3.89 volts to 5.00 volts. I then swapped the jump starters, and found that with the low voltage one connected, the meter still read 5.00 volts.



I do not know what solder Jaycar provided, but I am using it, and it seems to have produced good joints, even if I have used a bit more of it than a professional would have done.

[pentagram]

Hi
Did you get the kit from the UK??

If so could you let me know where please

Thanks

[Norman_E]

The original thread on this subject is here http://www.ybw.com/forums/showthread.php?t=255467 and as you will see it generated plenty of heat. I bought my two kits via the website linked in Bitman's post, 5th down on the first page. The link still works but as shown here http://www.jaycarelectronics.co.uk/p...W&form=SPECIAL the product is shown as out of stock. For two kits I had to pay an extra £52.30 shipping on top of the original £20 and £37.06 UK VAT on the total plus an £8 handling charge from Parcelforce. That made the total cost for two kits £256.86 - Still cheap compared to the cost of commercial units.

P.S. My guess is that they will be back in stock soon, and the reason for them being out of stock is that they are not just a collection of off the shelf parts, but include a ready wound coil and a pre programmed IC, both jobs which Jaycar do for you.

[Ubergeekian]

Ian, I still build them with kids in Bedford. You may remember me, or my wife Mary. I have had PCBs made and sourced most of the components or replacements with Peters help. Getting the code onto the PIC is becoming the biggest challenge.

PM on its way!

[Norman_E]

Sorry for the delay in updating this thread. I did solder up the circuit board for the second kit on boxing day. It was a doddle after the first one, and took less than half an hour. I have also fitted both units in their boxes and soldered the cable provided to the transducers. One point to note is that unless you file the socket for the transducer very thin, you will not be able to put a gland nut on the inside, there is just not enough thread on the cable glands. My solution was to mill a small flat, then drill the hole 29/64inches and tap the hole 1/2 inch UNF so that the gland can be screwed in.

My wife appears to have arranged an unending succession of dinner parties and visits for the season, so progress is slow, but I hope to encapsulate the transducers in a couple of days time. I am considering a method of encapsulation that does not involve using the plastic nut, and risking adhesive getting on the threads. More to follow once I have tried it.

The photo shows how little thread there is on the inside.



I cut down the adhesive labels supplied by Jaycar, as I did not want to cover all of the transparent box lids.

[Bower15]

Its looking good!
I am one of the gang who placed an order and then cancelled, perhaps it now appears in haste. I am not sure i couls of assembled it without help as my electronics knowledge is zilch! Therefor i am finding your post exremely interesting and can not wait to see it fitted and working. I am now seriously reconsidering whether to order a kit or not, is there any chance that you could put together a build guide for numpties like myself, perhaps as a word document so we could print it out and refer to it.
Good luck with the rest of the project and the dinner parties!
Brian

[petehb]

Well spurred on by Normans build just ordered two, still only showing £20 postage etc so expect to get asked for the extra. Still a £260 punt reducing the annual antifouling pain has got to be worth it.

[Norman_E]

Bower, I am afraid it will be a bit of a time before I can install it as I am not planned to go to the boat in Turkey until I go out to launch it at the end of March. When you order the kit you get three pages of information from Jaycar plus a 17 page reprint of the two magazine articles. There is enough information there to do the build, though I did find the web page that I linked very useful for correct identification of the resistors, which are nowadays tiny things compared to the ones of my youth, so an illuminated magnifier also proved very useful.