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Author Topic: +, -, GND  (Read 2368 times)
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I understood until now, that electronics, when it uses GND (ground), it means " - " (minus).  On a motor I've got,  it has a + (plus), - (minus), and GND (ground). What does the GND do?  smiley-confuse
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GND is really the reference point. If you are standing at street level, the first floor is one level above ground (so you might call it plus) and the basement is one level below ground (so you might call it minus).

As for your motor, what type is it?
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Wouldn't surprise me of the GND tab on the motor goes to the can, so assuming it's brushed you can easily add some caps for suppression.
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In a house you would call it the hot,neutral and earth ground
You would never use a ground as a neutral although it technically would work
ground is more for protection(from say shock or noise)
in a circuit you assume - means gnd when it really doesn't, most circuits are simple so people say ground but it is truly negative
on a battery you say its the positive and negative terminal, there is no ground terminal maybe only a ground connection
on the motor the ground is a connection to the chassis, this would protect you from shock if say the positive wire was touching the chassis and potentially could electrocute you, instead it hits the ground and would trip the overload or watever protection device implemented
now gnd in a dual polarity circuit means the common connection point and has no relation to the actual earth ground, so it does get a little confusing
in that case it refers to like said before the common reference point, but in this case with a motor it refers to earth ground used for protection that should(but isn't always) at the same potential as the negative leg of the supply
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As to Nick Gammon, I have a 1000kv 400xt brushless motor. www.hobbypartz.com/40tyoubrmo.html
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The "ground" doesn't actually exist.

It is merely a term used for the point in a circuit at which all voltages are measured with reference to.  It is entirely arbetrary what that point is.

Normally the "ground" node of a circuit is that node to which the majority of components are connected to.  If there is no such node, then 9 times out of 10 it is taken to be the point of lowest potential in the circuit - for instance the negative terminal of a battery.  Other circuits may take that point to be a place where the other voltages in the circuit cancel each other out.

The Arduino (and the Atmel datasheets) actually label things wrongly.  They talk of Vcc and GND as pins, which is entirely wrong in every respect.  What they should actually be talking about is Vss and Vdd - the source and drain voltages - and all voltages in the data sheet are measured with respect to Vss (Max Vdd above Vss = 5.5V for example).  The "GND" pin may not be connected to the same node as you have taken a GND in the rest of the circuit.  Vcc itself means "Collector voltage", and is as relevant to a CMOS system (which uses MOSFETs, not BJTs) as the ants crawling up the wall are to the current value of the Dow Jones index.

As far as motors are concerned, the "GROUND" could be many things.  For instance:

* It may be a connection to the metal exterior of the motor, to be used for noise reduction and/or safety.
* It may be a reference point for applying the voltages to the + and - pins - the motor might be inteligent, and you apply voltage to + and GND for spinning one way, and - and GND for spinning the other way.
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Vcc and GROUND are pins... designated places where these Sources are found and connected to. As to VCC most all the people learning here don't realize that Mosfets are relatively New parts... ALL Logic less than 30 years ago WAS Transistors at that time Cmos was the New kid on the block 40 years ago the Vast majority od electronics produced was still vacuum tubes. Power mosfets were very rare (N Ch) and P Ch were impossible smalll low current devices that were difficult to use as they were most fragile and had Rdson values it the 10's to 100's of ohms. I can clearly remember CD4017's that cost $12.00+ each, a CD4022 was 8 dollars in 1972 and a CD4011 was $2.31 and I was making 7.25/hr I got a raise to 9.00/hr and thought I could buy the world (It's a bit over $30.00/hr now)... and pop bottles were worth $.02 Ea refund value and a guy could collect 5 of them and buy enough candy to last all afternoon. There were also a great surprising number of people that believed the moon was made of Green Cheese. Luddites were coming into their own... sometimes I wonder if they hadn't the right of it.  <BG>

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As to Nick Gammon, I have a 1000kv 400xt brushless motor. www.hobbypartz.com/40tyoubrmo.html

That motor doesn't have +/-/gnd, it has red/black/yellow phases - its a 3-phase sensorless brushless motor.
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I do actually need more info on the motor
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Idk without a datasheet its hard to say exactly what that motor needs
just says 12v,
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As to Nick Gammon, I have a 1000kv 400xt brushless motor. www.hobbypartz.com/40tyoubrmo.html

That motor doesn't have +/-/gnd, it has red/black/yellow phases - its a 3-phase sensorless brushless motor.
What is a 3-phase sensorless brushless motor??
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Quote
What is a 3-phase sensorless brushless motor??
See:-
www.atmel.com/images/doc8012.pdf
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the document is WAY too long and complicated!
In a nutshell please...
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Wikipedia it
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Wikipedia it
Makes a change from "JFGI" I suppose...
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