Depth Sounder Questions

[squire]

no can't help myself fitzy sorry.IF ALL THE ABOVE WERE TRUE Can someone please tell me WHY DO WE HAVE FUSES IN CARS ON THE POSITVE WIRES? THEY WOULD SERVE NO PURPOSE!!!!!!!!!

Im not disagreeing with you guys. however the hose analogy. It would eventually burst due to the fact that the Water main has a greater pressure in it and if nothing else was connected to it, it would withstand the outside pressure for a while that is it. ie different amperage wire 10 amp wire 5 amp fuse. 5 aMp fuse will blow. Resistors in circuitry are exactly the same. However we all agree that there has to be and outside influence to make this happen and sometimes this can occur.Its like saying my boat motor started yesterday but won't start today. It is not about who is right or wrong. We all know the laws of Physics so with all of us knowlegeable people we should be able to fix adams sounder don't you think? Lets leave it alone.

[elmo]

Most cars have their negative terminal earthed to the chassis, some European cars don't and then it doesn't matter whether the fuse is close to the positive or negative. (but be vey careful with radios cd players etc as some have positve bodies) However, it is convention and safe practice to locate the fuse as close as possible to the source.

Fuses in cars with common chassis and negative terminals are on the positive wires because they need to be as close as possible to the source of energy in case of a fault.
Just say you accidently or inadvertently melted or rubbed the insulation off the conductor. It is quite feasible that the fuse didn't blow because there was no circuit (return path). Now, if this bare section of conductor is moved and touches the chassis, it is in effect a dead short across the supply with absolutely no protection.

This can lead to fires or even explosions.

[elmo]

quote: It would eventually burst due to the fact that the Water main has a greater pressure in it and if nothing else was connected to it, it would withstand the outside pressure for a while that is it.

Wrong, the water main has more than likely a greater flow potential but exactly the same pressure.

[elmo]

The pressure of your home water system is determined by the height (head) of water. That's why towers and reservoirs reach up to the sky.

For example.

I'll assume straight sided towers for ease of area calculations.

Pressure is defined as force per unit area. (pounds per square inch)

Tower One has dimensions of 1 foot wide by 1 foot deep by 10 feet tall.
Volume = width x depth x height = 10 cubic feet
Water weighs approx. 62 pounds per cubic feet so the total weight is equal to 620 pounds (62 x 10)
Area = width x depth or 1 square foot or 144 square inches
Therefore pressure = 620 pounds divided by 144 square inches = 4.3 pounds per square inch.


Tower Two has dimensions of 10 feet wide by 1 foot deep by 1 foot tall.
Volume = width x depth x height = 10 cubic feet
Water weighs approx. 62 pounds per cubic feet so the total weight is equal to 620 pounds (62 x 10)
Area = width x depth or 10 square feet or 1440 square inches
Therefore pressure = 620 pounds divided by 1440 square inches = 0.43 pounds per square inch.

Only the height (head) of water effects the pressure.

[squire]

Yep thats great Elmo got absolutely no idea what you're talking about but thanks for your thesis. Gravity is an amazing thing isn't it?
does the same apply for a dam?

[Big_Muddie]

I can't help but make a comment on this thread.

Lot's of lively debate about many things - maybe not specifically addressing the original post but informative nonetheless.

From many of the posters I have learned some things that I was previously not greatly interested in - but the debate here sparked (sorry - couldn't help myself there) my interest and resulted in my store of knowledge being increased.

Thanks particularly to Elmo for the explanation of water pressure and basic car electronics.

[giantgourami]

How about I add this in..... and you can all come up with your theories..

The actives where not from the same battery.. one was from the main and the other was from the spare .. would this make a difference?


anyway what you gots to say about navmans?


adam

[predator]

and a word from Professor Julius Sumner Miller.






























asks. "Why Is It So?".

[Heath]

Adam you may find that you have either blown a fuse internally if it has one if not you will find it will have cooked one of the resistors on the circuit board. Sorry heath if both were connected to the positive the a circuit would have been complete hence a blown circuitry component. Adam message me and I will quite happily have a look at it for you regards Squire.

How??? Conventional flow of electrons IE from POS to NEG. If there was no neg polarity how could there be current flow?

I'll use a simple example a 12v light globe with both ends connected up to only the Positive. Will it light up?...no, can you measure voltage across both leads when connected up to 1 pol only???

Not slinging mud Squire, just interested in how it could have caused damage to circuitry if it was connected to 1 pol only.

[Heath]

How about I add this in..... and you can all come up with your theories..

The actives where not from the same battery.. one was from the main and the other was from the spare .. would this make a difference?


anyway what you gots to say about navmans?


adam

Ahhhh now we get to the root of the cause.
YES it makes a BLOODY big difference

You now have a cct. Both batteries will have their earths connected together. Especially with 2 batteries, you have the problem of each battery not being the exactly the same voltage. Now lets say you have 1 battery & is fully charged at 12v & the other battery which has been used is say sitting at 10v, if you measure accross them you will measure 11v, now what happens when you connect up 2 batteries in this situation is that the flat battery will draw current from the good battery, eventually equalising at the sum of the 2 original voltages, this is called equalising.

What you have done is made a connection that has attempted to achieve this through your little sounder & as a result its gone KAPUT!

Ahhhh, dear o' dear..... good clean debate though fellas 8)

[squire]

Heath if you read post 7 I corrected myself. So here it is again.
Sorry guys I shall rephrase that. What I mean is that a positive flow through a circuitry board where there is a resistor and a voltage regulator will burn out or pop a resistor. I'm not talking about a completed curcuit on the boats system Ie +ve and _ve. Sorry heath I misread the statement. however sometimes when you have 2 wires connected to a +ve you can actually become the -ve especially in an aluminium boat.
Regards Squire.

[squire]

There we have it the outside influence. Can we all agree on that?