Options for adding gauges to Yanmar 3GM30F

[acem]

I suggest marine or other waterproof guages for your boat as most automotive guages are not waterproof.

Do not use a tee for the temperature sensor. The sensor should protrude into the water passage or it will affect its reading. Additionally the location of the sensor is important as well. Ideally the sensor is very near the thermostat.

A tee will work fine for the oil pressure sensor.

Guages are nice but idiot lights with a buzzer will get your attention best. A combo of both are ideal.

I personally prefer mechanical guages. You could use Murphy switchguages. They are mechanical guages that can activate a buzzer/light and/or shut down the engine when the temperature is too high or oil pressure is too low. I use these on my farm's irrigation engines since they operate unattended.

https://www.fwmurphy.com/products/gauges

Thx-Ace

[stormalong]

Originally Posted by Wotname

Well if we are going to pedantic, let's do it properly - .

Considering 'good old run of the mill' analogue gauges.

Both the temperature sensor and the pressure sensor varies their respective resistance of the unit with the corresponding changes of temperature and pressure.

These changes in the resistance of the sensors causes changes in the current flowing through the sensor. The gauge responds to this changing current by measuring the change in the magnetic field of the meter movement.

So it is more accurate to say the gauges are magnetic field gauges but loosely speaking they are amp-meters because without the current flowing through the meter movement, they would not deflect the pointer.

Analogue voltmeters are really only a special case of amp meter - one that has a high value series resistance in the meter movement.

Okay, now back to regular programming .

Well, if we are going to be pedantic there is no such thing as an amp meter. All analog meters are voltmeters. A so called amp-meter measures the voltage drop across a shunt resistor and is calibrated in amps. A shunt is a resistor that is calibrated to produce an accurate voltage proportional to the current flowing through it. A potentiometer is called that because it meters (controls) the electrical potential, aka volts. A typical potentiometer circuit has a fixed voltage across the two ends of it's resistance and the adjustable brush divides that voltage.

Okay, now we can get back to regular programming.

[Wotname]

Originally Posted by stormalong

Well, if we are going to be pedantic there is no such thing as an amp meter. All analog meters are voltmeters. A so called amp-meter measures the voltage drop across a shunt resistor and is calibrated in amps. A shunt is a resistor that is calibrated to produce an accurate voltage proportional to the current flowing through it. A potentiometer is called that because it meters (controls) the electrical potential, aka volts. A typical potentiometer circuit has a fixed voltage across the two ends of it's resistance and the adjustable brush divides that voltage.

Okay, now we can get back to regular programming.

Opps - back to the off topic section of this thread, my apologies to the OP but the above information needs to be corrected

Nope, most analogue meters are amp meters and the most common (the moving coil meter) is most definitely an amp meter i.e. the pointer deflects proportionally to the value of the current flowing through the meter movement. It does not matter what the scale says on the face of the meter, the meter movement responds to the current flowing in the movement. Take the case of a analogue multimeter, there is only one meter movement but many scales. The circuitry surrounding the meter movement can be altered by the various switches so the meter will display a variety of volts and amps (both Ac and DC).

If the meter movement requires say 50uA for FSD, it matters not what voltage is presented to the meter, it will deflect to FSD when and only when 50uA is flowing.

More info here (while this refers to analogue multimeters, the principles remain the same) https://www.electronics-notes.com/ar...es-it-work.php

Digital meters are different and many (most/all??) are voltmeters (AFAIK)

And yes, I concur with your description of the potentiometer

OK, now back to regular programming

[GordMay]

This tutorial gives an excellent description of how analogue meters work:

“... The most basic type of DC analogue voltmeter is the “permanent-magnetic moving-coil” (PMMC) meter, also known as a D’Arsonval movement.
This type of analogue meter movement is basically a current measuring device (termed galvanometer) which can be configured to operate as either a Voltmeter or as an Ammeter, the principal difference is the way in which they are connected in a circuit. The moving-coil movement uses a fixed permanent magnet and a coil of very thin wire which is allowed to move (hence the name “moving-coil”) within the magnetic field of the magnet ...”
Voltmeter ➥ https://www.electronics-tutorials.ws/blog/ammeter.html
Ammeter ➥ https://www.electronics-tutorials.ws/blog/ammeter.html

[tkeithlu]

Hey, Stormalong!

Let's really split hairs over terminology. Potentiometers ARE voltmeters. They measure "potential," which is "voltage."

[B25Matt]

I have not. I basically copied stuff already out there. PM me and I'd be happy to send you my code.

Originally Posted by jacktheflyer

I'd be very interested in this. Have you posted your project anywhere?

[Spot]

-Will our intrepid OP read this far, wading through links and theory of elec-trickery and needle meter operation?
-Will they give up on their quest for new sensors and instruments to gauge the engine's operation and stick with warning lights?
-Will they forsake the marine and automotive solutions and dive deep into the stamps and shields of Arduino? Or will they opt for the action of the Murphy's?

These, dear Readers, are questions yet unanswered...

Dmksails, how are you doing? Any more plans or decisions related to the install?

[rdempsey]

I did this 10 years ago on my 2gm20f. Should be the same for the 3 ?
Should be easier now with Internet shopping.

https://www.cruisersforum.com/forums...tml#post412123

[goboatingnow]

Err just to clarify

A potentiometer is a three terminal component

A Variable resistor is a resistance value that can be adjusted. It’s a two terminal component . A rheostat is also the term for a variable resistor , but less used these days

Senders are variable resistors

A potentiometer is not a volt meter

The term potential -meter comes from the original use of a using it to supply a reference voltage to zero a galvometer movement to measure an unknown voltage

[stormalong]

Originally Posted by tkeithlu

Hey, Stormalong!

Let's really split hairs over terminology. Potentiometers ARE voltmeters. They measure "potential," which is "voltage."

Ok, lets split hairs. Here is the Wiki on potentiometers.

https://en.wikipedia.org/wiki/Potentiometer

A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider.[1] If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat.

[stormalong]

Originally Posted by Wotname

Opps - back to the off topic section of this thread, my apologies to the OP but the above information needs to be corrected

Nope, most analogue meters are amp meters and the most common (the moving coil meter) is most definitely an amp meter i.e. the pointer deflects proportionally to the value of the current flowing through the meter movement. It does not matter what the scale says on the face of the meter, the meter movement responds to the current flowing in the movement. Take the case of a analogue multimeter, there is only one meter movement but many scales. The circuitry surrounding the meter movement can be altered by the various switches so the meter will display a variety of volts and amps (both Ac and DC).

If the meter movement requires say 50uA for FSD, it matters not what voltage is presented to the meter, it will deflect to FSD when and only when 50uA is flowing.

More info here (while this refers to analogue multimeters, the principles remain the same) https://www.electronics-notes.com/ar...es-it-work.php

Digital meters are different and many (most/all??) are voltmeters (AFAIK)

And yes, I concur with your description of the potentiometer

OK, now back to regular programming

Look again. An analog meter has a coil of a fixed resistance. By ohm's law the only way to change the current through a fixed resistance it to change the voltage. To double the current you must double the voltage. Therefore, an analog meter measures voltage.

For example: A shunt is rated by volts per amp. A 100 millivolt, 100 amp shunt produces 1 millivolt for each amp that flows through the shunt. The meter that displays the current is driven by the voltage, not the current.

OK, now we can return to regular programming. Sorry to have hijacked this thread. On technical maters it is important to get the facts straight.

[Wotname]

Originally Posted by stormalong

Look again. An analog meter has a coil of a fixed resistance. By ohm's law the only way to change the current through a fixed resistance it to change the voltage. To double the current you must double the voltage. Therefore, an analog meter measures voltage.

For example: A shunt is rated by volts per amp. A 100 millivolt, 100 amp shunt produces 1 millivolt for each amp that flows through the shunt. The meter that displays the current is driven by the voltage, not the current.

OK, now we can return to regular programming. Sorry to have hijacked this thread. On technical maters it is important to get the facts straight.

I agree it is very important to get the facts right but it seems you have been blinded by taking only a quick look at the facts rather than digging deeper into the issue.

While there are many ways of determining a voltage value, the moving coil analogue meter is not one of the best as it responding to current flow, not voltage. Your first paragraph is mostly correct but it isn't the full story.

Consider a moving coli meter which has a FSD of 100uA and drive it with constant current source of 100uA, the pointer will move to FSD. Drive it with 50uA (from a constant current source), the pointer will move to HSD (half scale deflection). Now drive it with a varying voltage source that is current limited to 1uA, the pointer remain at 1% deflection regardless of the voltage supplied.

So no, the moving coil meter movement is not a voltmeter except in certain circumstances - admittedly most circumstances but not all.

Back to regular programming

[Wotname]

Originally Posted by rdempsey

I did this 10 years ago on my 2gm20f. Should be the same for the 3 ?
Should be easier now with Internet shopping.

https://www.cruisersforum.com/forums...tml#post412123

Excellent post and this should be very helpful to the OP

[stormalong]

Originally Posted by Wotname

I agree it is very important to get the facts right but it seems you have been blinded by taking only a quick look at the facts rather than digging deeper into the issue.

While there are many ways of determining a voltage value, the moving coil analogue meter is not one of the best as it responding to current flow, not voltage. Your first paragraph is mostly correct but it isn't the full story.

Consider a moving coli meter which has a FSD of 100uA and drive it with constant current source of 100uA, the pointer will move to FSD. Drive it with 50uA (from a constant current source), the pointer will move to HSD (half scale deflection). Now drive it with a varying voltage source that is current limited to 1uA, the pointer remain at 1% deflection regardless of the voltage supplied.

So no, the moving coil meter movement is not a voltmeter except in certain circumstances - admittedly most circumstances but not all.

Back to regular programming

DUH? A constant current source adjusts the voltage to maintain the constant current through a circuit. To reduce the current through a circuit from 100ua to 50ua the voltage is cut in half. Whether you like it or not, an analog meter display is driven by the voltage applied to the meter.

Last time I looked there are no exceptions to Ohm's law.

[Wotname]

Originally Posted by stormalong

DUH? A constant current source adjusts the voltage to maintain the constant current through a circuit. To reduce the current through a circuit from 100ua to 50ua the voltage is cut in half. Whether you like it or not, an analog meter display is driven by the voltage applied to the meter.

Last time I looked there are no exceptions to Ohm's law.

You forgot to refute the essential bit which was "Now drive it with a varying voltage source that is current limited to 1uA, the pointer remain at 1% deflection regardless of the voltage supplied"

FWIW, the first bit was simply a demonstration that the moving coil responds to current. The bit above demonstrates it doesn't respond to voltage.