DIY Electronics?

[jviss]

I just ordered one of these. I had forgotten your note about sensor resistance range; the one I got is 0-190Ω. I hope it works out! The US-based eBay seller made me an offer for $75, so I couldn't resist. We'll see.

Update: there's a jumper on the unit to select between 0 - 190Ω or 240-33Ω. For the latter you put a jumper between the "Switch" and "GND" terminals.

I got a great deal. I had put a watch on the unit on eBay and then the seller offered me a discount. I got it for $75.

 

[jviss]

Question: what do folks use for sensor wire on a boat? I think 16 ga. tinned wire is overkill. Something much smaller is adequate, electrically.

Also, what colors for sensors?

What say you?

 

[Davidasailor26]

Question: what do folks use for sensor wire on a boat? I think 16 ga. tinned wire is overkill. Something much smaller is adequate, electrically.

Also, what colors for sensors?

What say you?

I’ve used leftover old 22-4 copper wire. Handy to have 4 wires bundled together, but the stuff I used was not stranded. About a month ago my exhaust temperature sensor failed and I eventually traced it to a fractured copper wire.

 

[jviss]

I’ve used leftover old 22-4 copper wire. Handy to have 4 wires bundled together, but the stuff I used was not stranded. About a month ago my exhaust temperature sensor failed and I eventually traced it to a fractured copper wire.

Yea, I get that. I am looking at some 24AWG stranded, tinned wire, but to use color coding it might add up to a lot of money.

 

[Davidasailor26]

Depending on the cost and difficulty of running wire you could also consider just putting individual devices in different places and having them communicate wirelessly. I run wires to my temp sensors on the engine, but for my refrigerator temp sensor and battery monitoring I use discrete devices. The battery monitoring is done by a Pi Pico like device with built in radio - Adafruit Feather RP2040 RFM69 Packet Radio - 868 or 915MHz . In my refrigerator I put an Atmega 328P (DIY Arduino) connected to its own transceiver ( Adafruit RFM69HCW Transceiver Radio Breakout - 868 or 915 MHz ).

The remote devices do need to be self-powered, but in the case of my battery monitor that’s easy enough since the battery wires are right there, so I use a buck converter to get the voltage I need from 12V. For the refrigerator I use 3 AA Lithium batteries (that work in the cold).

In my case all this data comes back to a Pi with its own transceiver, but you could use an Arduino or clone with a transceiver instead.

 

[jviss]

Now, if I could only get a great deal on a NMEA2000 to SIMRAD SIMNET adapter cable. Yikes! They are like $43 on eBay!

 

[Davidasailor26]

Same on Defender. This is the one I got (for $39 in 2019) - Simrad Simnet to NMEA 2000 Cable Adapter - 24006413.

 

[jviss]

The cheapest I've found a female Micro-C connector so far is $13.50. Then a Simnet pigtail, used(!) is about the same. So DIY is approaching factory-made pricing anyway.

What kills me is I am pretty sure I have one of these, somewhere, in that box of new STNG cables and giblets that I can't find since the move.

 

[jviss]

Well, I'll be! Best price for the Simnet to Micro-C cable - West Marine! $27.99. Free ship to store. (About 3.5 miles from me.)

 

[jviss]

So, @Davidasailor26 what do you think about hookup wire for the instruments and sensors to the CX5003?

I'm thinking 24AWG tinned, stranded copper.

I found a kit on Amazon of six colors 50' each for $26, or 25' each for $16. It won't yield "proper" ABYC color coding, but then, the color code isn't sufficient to cover all the uses anyway.

I could go up to a larger gauge, up to 18AWG, but my intuition is that 24AWG is sufficient. What say you?

 

[Davidasailor26]

From a current standpoint 24 should be plenty. My understanding is that the reason for the ABYC limitation is more about supporting its own weight and handling tension. I’m certainly using thinner than 18 AWG, but like I said my connectivity hasn’t been perfect, so YMMV.

I’d consider how critical you see the function of the wiring and how easy it would be to fix or rerun. In my case the sensors are a nice-to-have and if I need to rerun them it’s just another project, so that was part of my decision too.

 

[Techstyle]

I found it difficult to find wire on Amazon that was both tinned copper and pvc (vs silicon). I could have bought Anchor and did for other, higher duty projects, but for some of the sensors I used some RGB LED Wire that was stranded tinned copper, PVC and 22ga. I got 100ft (well 400ft really) for $16.99, worked great - Amazon.com

 

[jviss]

I'm returning the 24AWG wire set, it's just to flimsy/fragile. I have a collection of 16AWG marine stranded wire in various colors, I might just use that.

I received the Simnet to Micro-C cable. There's something satisfying about a good connector! I can see why Simrad came up with their Simnet connector, it's not much larger in diameter than the cable, and therefore requires much smaller holes to route than Micro-C. And not many folks are field-terminating Micro-C, so there you are.

What wire should I tap for RPM?

 

[Davidasailor26]

What wire should I tap for RPM?

On my Yanmar with Hitachi alternator there’s a yellow wire off the side of the alternator housing that provides the tach signal.

The signal off that wire is a square wave between 0V and alternator output. I put that through an option-isolator and count the pulses as interrupts per second with a Pico microcontroller.

 

[jviss]

On my Yanmar with Hitachi alternator there’s a yellow wire off the side of the alternator housing that provides the tach signal.
View attachment 219279

The signal off that wire is a square wave between 0V and alternator output. I put that through an option-isolator and count the pulses as interrupts per second with a Pico microcontroller.

Nice!

 

[jviss]

Now that I got my CX5003 and the necessary NMEA2000 cable, I looked into sensors for the two tanks that don't have them: the waste tank and the bow water tank.

So, I guess KUS acquired Wema? Where have I been?

I was a bit surprise at the cost of the sensors. Wow. Oh, well. The gauges are reasonably priced, in my view.

Since I have engine coolant temp and oil pressure gauges, I assume that I have appropriate sensors for the CX5003.

I wonder about the "volt signal" terminal. Does that mean one can only monitor one battery's voltage?

 

[jviss]

^^^ @Davidasailor26

 

[Davidasailor26]

I wonder about the "volt signal" terminal. Does that mean one can only monitor one battery's voltage?

I haven’t played with one of those, but looking at the picture that would be my guess. Unless there’s any way to reconfigure it to use an input like trim tab as a second voltage?

If you’re going to put an Arduino on your network a work around could be to use the trim tab as a second voltage sensor and let the CX5003 broadcast it that way. Then have the Arduino receive the trim tab NMEA sentence and turn the value into a new sentence for bank 2 voltage. But if an Arduino is involved anyway you could just use it to read multiple other voltages itself and put them on the network.

 

[jviss]

I haven’t played with one of those, but looking at the picture that would be my guess. Unless there’s any way to reconfigure it to use an input like trim tab as a second voltage?

If you’re going to put an Arduino on your network a work around could be to use the trim tab as a second voltage sensor and let the CX5003 broadcast it that way. Then have the Arduino receive the trim tab NMEA sentence and turn the value into a new sentence for bank 2 voltage. But if an Arduino is involved anyway you could just use it to read multiple other voltages itself and put them on the network.

I like the way you think.

 

[Techstyle]

I bought sensor for my fresh water tank to replace the original from Aliexpress for $22. Just need to select which one you need - https://www.aliexpress.us/item/3256801162303732.html