When its all done and tested get a tin of conformal coating from RS, Maplin or similar and coat the board and components liberally to prevent deterioration from salt air.
Does conformal coating make future repairs difficult? I ask because in my youth a friend and I made radio controls for model boats from parts salvaged from old military radio sets. He did most of the building but I stripped the parts from the old sets. When I opened one the works were entirely covered with thick anti fungal "paint" and many of the parts were useless.
I have now made an executive decision, and will not fit the switches, just bridge the terminal posts. The reason is that I do not want anyone turning them off. I will comnnect them to the bilge pump circuit breaker switch on the main panel, via a concealed switch under the chart table, so that I can isolate them, in need.
Next job is to do the internal voltage adjustment. The instructions are a bit unclear in that they say connect a digital multimeter reading DC volts between TP1 and TP0, which is clear enough, but then it just says "apply power and adjust VR1 for a reading of 5V. The question is, do I just connect a charged 12 volt battery, which could be anywhere up to about 13.7 volts, or must I connect an exact 12 volt source?
Last edited by Norman_E; 29-12-10 at 19:30.
Working on immortality - One day at a time.
As I said, when its all tested and complete!
It's nothing more than a passive varnish, yes it makes desoldering and sometime resoldering a bit of a pain but not nearly as much of a pain as intermittent faults or early fatality of a circuit through the effects of corrosion.
Norman - most of these ICs can cope with more volts than 12 but worth checking on a data sheet or wait for confirmation from one more clued up than I.
I dislike thread drift but........the PIC controlled buggy sounds just the job to stave off the cabin fever. Any chance of link, please ?
Brainibot. I'm not sure how easy they are to get hold of nowadays - Rapid used to do the kits but I think i was their main customer. IIRobotics in Edinburgh still list them, at rather more than Rapid used to charge because they re-engineered the drive train a bit.
Peter Balch, who designed them, has a prototype Brainibot II with a much more powerful PIC, IR proximity sensors and a USB link for programming, but nobody has ever ordered enough to make production worthwhile.
If you're interested, PM me and I'll have a look round - I may be able to dig out a PCB and programmed PIC. You'd have to source everything else yourself, though.
I Googled for studies of the efficacy of ultrasonic antifouling and came across what appears to be the original source of this design, at Silicon Chip magazine. The article includes this interesting warning that caught my eye:
You better make sure you keep it very dryWARNING!
This circuit produces an output voltage of up to 800V peak-peak to drive the ultrasonic transducer and is capable of delivering a severe electric shock.
DO NOT touch the drive unit output terminals, the PC tracks leading to CON2 or the transducer terminals when power is applied.
To ensure safety, the PC board must be housed in the recommended plastic case, while the transducer must be correctly housed and fully encapsulated in resin as described here.
If you have the PIC with code on it then I certainly have a PCB or two to spare. I also have a Rapid parts list for all the components if some one wants a go!!
Sorry for thread drift, I am interested in the Ultrasonic AF kit and will probably indulge if it works out for you.