Ground?

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Lightfire

Joined Oct 5, 2010
690
There is no reason to bump this thread.

The basic idea is to place the switch(es) (and fuses, too) in the circuit path that is furthest away from what has been declared to be ground.

I think you've had sufficient input on this subject.
Originally posted by SgtWookie at my earlier post.

So, I really don't know what is ground or whatever. I got the feeling that the ground that most people are saying is the third wire. What is that? How to install that wire? It can be installed in battery? How?

Thanks...
 
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SgtWookie

Joined Jul 17, 2007
22,230
Our OP doesn't understand what "ground" is. Hopefully, the Wikipedia link that I posted will help to clear up their confusion.
 

SgtWookie

Joined Jul 17, 2007
22,230
It could. Battery powered projects are usually "floating" - they have no electrical connection to earth ground. However, it is still common to declare one point of the circuit to be the 0v reference. In the case of a single-supply system, it is most frequently the negative side that is declared to be 0v, or the ground reference point.
 

CDRIVE

Joined Jul 1, 2008
2,219
After the OP reads those articles be prepared to answer the inevitable question regarding long running discrepancy of the Earth GND vs. Chassis GND symbol. I was taught using the convention that we use here on AAC and in all the Spice programs I've used. Over the years, most schematics have also followed this convention but there's always been the occasional exception. If I were to guess, I'd think that the most probable cause for the discrepancy was born between the electronics industry and the electrical (Electricians Union) industry but not sure. To further muddy the water, most circuits today don't employ a metal chassis. Here at AAC we're dealing with mostly with PCB design which (technically) should be drawn as an inverted triangle to indicate a Common Gnd, Board Gnd, System Gnd, Circuit Gnd, Floating Gnd and any other above ground terms I've missed. From an aesthetics point of view I've never liked it.

There's yet another ground symbol that I use. See attachment.
This is a classic "Bar Napkin Ground Symbol" that I like to call the "Lazy Z". :D
 

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Wendy

Joined Mar 24, 2008
23,415
I'd never seen the Lazy Z, I'll have to remember.

Ground, as referenced to electronics only, is the common point. It is where you put the negative lead from your meter, and the other voltages are measure with the positive meter lead.

Some circuits use more than one power supply. Op amps are the usual example, they use two voltages, a plus and a minus, and ground is where they connect. This is a bit advanced for you, but not too much so.

My personal convention, where there is only one power supply (or battery), is that negative is always ground. This is pretty common, but not written in stone.

There was a time with cars, many decades of years ago, that ground was the positive lead from the battery. This has pretty much gone away.
 

studiot

Joined Nov 9, 2007
4,998
The difficulty with calling the chassis 'ground' is that it may not be.

At one time many televisions and mains radio sets were build on metal chassis. Many parts of the circuit were connected to chassis, but the chassis was not earthed ( connected to the incoming mains earth ). Indeed in some models the chassis was live.

Although this is no longer practiced, the symbol for connection still remains and some assemblies of industrial apparatus is built into a metal frame. Connections to such a frame is still correctly represented by this symbol.

CDrive's lazy z usually represents mains ground.
 

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