Printable Version of Topic

Posted by: dimmer May 24 2004, 05:26 AM

I am looking at the current flow diagrams, and can't figure them out. Can anyone give me some insight on how they go?
I started up the car and my brake warning light is now on and so is my turn signal light ( very dimly lit). I figure I must have a short somewhere.

Posted by: ablose58 May 24 2004, 05:50 AM

They read very similar to a road map. it just completes a loop.. you have a + and a-, and they meet at a termination point. without it being in front of me I can't help you now but maybe someone else will chime in. AL

Posted by: type47 May 24 2004, 07:33 AM

it might help if you could think of the electrical current "flowing" from + to -. the - is also known as "ground". basically, the current flows from the + of the battery to the - of the battery, since the - of the battery is connected to the chassis, the chassis is called the ground connection. in the 74 electrical diagram on this site, the bottom of the picture is "ground" and the current can be traced thru all the components.

Posted by: SpecialK May 24 2004, 08:41 AM

Actually, current flows from the - battery terminal, to the + battery terminal in a DC circuit. Try swapping out the turn signal relay and see if that does it.

Posted by: SirAndy May 24 2004, 12:15 PM

Actually, both is right, somewhat ...

1) there is the "technical current flow", which is from + to - and is used in all electrical diagrams and circuit layouts ... (this is the one you want to remember when trying to read a diagram)

2) then there is the "scientific current flow", which is from - to +.
the electrons still move from + to - btw., but it's actually not the electrons that move at all (on their own), it's the "holes" or empty space inbetween the electrons that moves, from - to + . by doing so, it "pushes" the electrons the other way (from + to -) ...

confused now? don't worry about it, chances are, you won't need 2) anytime soon.
Andy

Posted by: John Jentz May 24 2004, 12:22 PM

If you are talking about the "Current Track" diagrams for 74+, each circuit has a number on the ground side (bottom) . Follow the 12v from the top of the page through the stuff it works to ground on the page bottom.

Posted by: F4i May 24 2004, 12:31 PM

Problem is nobody told old Ben Franklin or michael Faraday.

For reading the 74 and up diagrams I like to think of it as water. It runs downhill (down the page)from positive to negative.

Posted by: phantom914 May 24 2004, 12:48 PM

OK Andy, you got pretty close. + to - is conventional current flow and is what geeks, also known as engineers, work with. - to + is electron current flow. Electrons move from - to +. Holes move from + to -.

Andrew

Posted by: SirAndy May 24 2004, 01:00 PM

close enough it's been what, 20 years now that i had to sit through this in school last time.
plus, i don't have the english lingo down for all the stuff, i could tell you the german words and names but that wouldn't help much, now would it?

i think the important lesson here is: THAM ™ (The Holes Are Moving!!!!)

Andy

Posted by: phantom914 May 24 2004, 01:30 PM

Sir Andy,

Electrons are the charged particles that move when a current flows in a circuit. Speaking of "holes" moving is usually reserved for explaining semi-conductor theory. At least in Englisch

Conventional flow arose before the physics of early observations of electricity was understood. Electron flow is what arose as scientists learned the actual mechanisms of electricity. Now you can choose whichever convention makes you happy, although some electrical symbols make more sense with conventional flow in mind.

Andrew (geek)

Posted by: 94teener May 24 2004, 04:55 PM

I think today that most engineers, electrical techs and electricians think of current flow as electron flow. Electrons are "negative charged" particles, they are attracted only to a positive anode. Electrons repel oneanother. Think of electroplating, the negative anode erodes, giving up material, the positive anode (the object being plated) collects the negatively charged particles. Holes are the absence of electrons, they are not matter.

Phil

Posted by: Jeff Bonanno May 24 2004, 05:00 PM

negative 'cathode' erodes... think cat- for place where cations are generated (or electrons leave, oxidation occurs) and an- for place where anions are generated (or electrons arrive, reduction occurs)

Posted by: TonyAKAVW May 24 2004, 05:09 PM

Just to add to the confusion, electron current is the net directional movement of electrons. If you put an electron into one end of a conductor (wire) it will take a really really long time for it to come out the other end... But since conductors have lots of free electrons, the instant you push one in, one will pop out on the other end, at nearly the speed of light. Since insulators have few free electrons, it takes a lot of potential (voltage) to push that electron through that large empty space.

Holes may not have mass, but then light has no mass, yet it has momentum...... very strange stuff.

-Tony