YAPP Low power Seatalk Anchor Watcher

[nigelmercier]

I would be interested in an NMEA version... there are tools for simulating NMEA (for example http://www.kagstrom.no/nmea_simulator.htm) if it helps...

This one is free, and works well: http://www.labsat.co.uk/index.php/en/products/free-satgen-nmea-software.html

 

[AngusMcDoon]

I would be interested in an NMEA version... there are tools for simulating NMEA (for example http://www.kagstrom.no/nmea_simulator.htm) if it helps...

Thank you for the link. The different versions of NMEA-0183 have different voltage level requirements. It changed from single ended output to differential during its life. The input side needs to be opto-isolated as well. It's the hardware aspect that would need testing on someone's boat.

 

[AngusMcDoon]

Regarding cutting square/rectangular holes in ABS.

What about making up a steel template with the correct sized hole and tape, or otherwise secure it, to the box and just "mill" out the hole with a Dremel or similar?

Good idea. I'll knock up a template.

Hang on. How do I make a square hole in steel? Do I need a template?

 

[nigelmercier]

... The input side needs to be opto-isolated as well...

+1

I've been looking at ways to read NMEA, and I have come to the conclusion that opto-couplers in the input (and output) are the best way.

 

[nigelmercier]

Good idea. I'll knock up a template.

Hang on. How do I make a square hole in steel? Do I need a template?

In the days when all project boxes were made of die-cast metal (Eddystone Box?) we (at the BBC) used to have a rectangular tank-cutter for a multi-way plug we used all the time. I did a search when you first posted the question, but couldn't find any.

 

[AngusMcDoon]

+1

I've been looking at ways to read NMEA, and I have come to the conclusion that opto-couplers in the input (and output) are the best way.

If you use an opto for the input it will cope with either a single ended or a differential talker. However, if you use a single ended input and the talker is differential then the talker can be damaged as one if its lines in one of its states will be +5V connected to ground at the other end.

Two major manufacturer of marine electronics produce their NMEA-0183 equipment with single ended talkers as this can be connected safely to anything, whereas a differential talker cannot always be. This is not compliant with the latest NMEA-0183 specification, but is electrically safe.

 

[Plevier]

If you use an opto for the input it will cope with either a single ended or a differential talker. However, if you use a single ended input and the talker is differential then the talker can be damaged as one if its lines in one of its states will be +5V connected to ground at the other end.

Two major manufacturer of marine electronics produce their NMEA-0183 equipment with single ended talkers as this can be connected safely to anything, whereas a differential talker cannot always be. This is not compliant with the latest NMEA-0183 specification, but is electrically safe.

Beware the single ended NMEA out from the Raymarine ST60 multi instrument (and probably the ST60 graphic as well).
The high is permanently +11V (approx) and the low is floating and goes to ground for signal.
This won't work with a single ended input - in my case a Garmin 750. I've had to put an opto in between (thanks to Nigel for the suggestion), worked fine.

 

[Hydrozoan]

Another expression of interest should you ever do one with NMEA input and the facility to power a stand-alone GPS unit.

 

[AngusMcDoon]

This is about as good as I can get for a square hole. I have round holes and countersinking sorted now.

 

[claudio]

This is about as good as I can get for a square hole. I have round holes and countersinking sorted now.

I haven't tried it but can't you take a sacrificial USB connector, mechanically couple it to your soldering iron and use it to melt the hole ?

 

[DinghyMan]

If you want a dead square hole how about a mortice chisel?

Seperate the two bits, use the drill to make the initial round hole then the push outer square section to make it a proper square

 

[rogerthebodger]

How about a corner chisel if doing it by hand.

https://www.google.co.za/#q=corner+chisel

 

[AngusMcDoon]

Thanks for the ideas for different tools. Not being into my woodwork I hadn't heard of either of them. Something new to investigate.

 

[DaveS]

I'm not sure that wood chisels would keep an edge long used on plastic, but it's not really my area.

On the overall concept, I like the idea of a low power consumption overnight "watchdog" that could be placed next to your head. The problem as I see it is that all the data is coming from other instruments that would have to stay powered up, which rather defeats the object. If position could be picked up from an internal GPS receiver, however, that could give a self contained low power gizmo that would be highly attractive.

 

[Hydrozoan]

Just a few thoughts on the hole question - very possibly all quite impractical, for electronic or other reasons!

1. Use a surface mount socket (e.g. http://www.l-com.com/usb-usb-type-b-jack-10-leads-black) - bulky, expensive?
2. Put board in box other way up, thus cutting U shaped hole from lid edge - easier to do neatly than cutting out a complete square?
3. Use a rubber grommet to tidy-up the hole edges, if it will deform enough to follow square corners neatly?

 

[AngusMcDoon]

I'm not sure that wood chisels would keep an edge long used on plastic, but it's not really my area.

On the overall concept, I like the idea of a low power consumption overnight "watchdog" that could be placed next to your head. The problem as I see it is that all the data is coming from other instruments that would have to stay powered up, which rather defeats the object. If position could be picked up from an internal GPS receiver, however, that could give a self contained low power gizmo that would be highly attractive.

The instruments in a typical boat system are small consumers of power. The big consumer is the chart plotter. Therefore, in my system anyway, it saves considerable power consumption by having that turned off. The power used by modern marine electronics is closely related to the size and type of display...big colour display, lots of power, small mono display, minimal power.

I have measured the consumption of the various components on my system. The instrument heads and their transducers are typically about 50mA with the light turned low. The chart plotter never goes below 650mA. I also want more than just position to be monitored, therefore I need the instruments on.

Would just a normal GPS handset give you a position change alarm? My GPS45 doesn't, but it is very old.

 

[AngusMcDoon]

Just a few thoughts on the hole question - very possibly all quite impractical, for electronic or other reasons!

1. Use a surface mount socket (e.g. http://www.l-com.com/usb-usb-type-b-jack-10-leads-black) - bulky, expensive?
2. Put board in box other way up, thus cutting U shaped hole from lid edge - easier to do neatly than cutting out a complete square?
3. Use a rubber grommet to tidy-up the hole edges, if it will deform enough to follow square corners neatly?

1) The jack looks good, but it's a lot of money.
2) I've never thought of that. I shall have a fiddle and see.
3) I'll try that too.

 

[Como]

This is about as good as I can get for a square hole. I have round holes and countersinking sorted now.

I'm not sure what size that hole is but have you looked at the QMax cutters such as https://www.toolshopdirect.co.uk/search.php?ssort=d&what=&search=square+qmax Ive used them in the past on Die Cast boxes so there should be no problem with ABS.

John