# Understanding Electronics Basics #1

Discussion in 'General Electronics Chat' started by cowboybob, Feb 16, 2012.

1. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
but thats the ω, I thought that stood for working (V) but also smaller version of Ω

2. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
So moving on, if I can get DX on cursor & DY that means you can use scope to find the slope, now don't get me wrong, I don't know what slope means other than derivitive

What were we finding with the slope?
An angle, why do we need an angle, to find the start of the wave?

So phase is where wave starts oscillation

So ω= amount of oscillations in a given period of radians per S, meaning you could double them for normal timescale

Ok, then there was db thingy you showed me, this is all slowly joining up isn't it

Last edited: Mar 23, 2012
3. ### cowboybobWell-Known MemberMost Helpful Member

Joined:
Oct 22, 2011
Messages:
3,052
Likes:
479
Location:
James Island, SC
YOU DA MAN!! You continually amaze me with your willingness to get into the guts of an instrument and see what it'll do.

DX is XB minus XA, or 4 seconds,
DY is YB minus YA or the or "amplitude" (voltage) level. In your case, it's showing zero. Try moving either cursor A or B to a point at the flat peak of the square wave and see if you can get it to read around 8.5VDC.

Cycles, or more accurately, frequency as expressed in "cycles per second" (cps) and the term Hertz are identical. It's just that Hertz did all the work discovering and analyzing and was finally given credit for that by the science community by redefining cps as Hertz (Hz).

And the web site with the trig functions is excellent. Bookmark that sucker because phase issues are all about sine (sin) and cosine (cos).

Yes, the aerial's actual physical length is 1/2 a wavelength (at a specified frequency). Antennae are a whole nother ballgame, believe me. Let's not even go there for the time being.

And the antenna/ground issue is also tied up in wave propagation that is best delayed, for now, in this discussion. Suffice it to say that the length of an antenna (plus its design) AND it's relative physical position above ground (literally, and both tied to a specific frequency), are absolutely critical to optimum transmission and reception parameters. Antenna theory is in a class all by itself.

Last edited: Mar 23, 2012

Joined:
Jan 12, 1997
Messages:
-
Likes:
0

5. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England

Just went for walk with bobby & Lou, although did have a sneak on phone to see replies

Well, I can't break or destroy anything by playing with computer, erm let me rephrase that, I haven't yet

8.58VDC

View attachment 62561

That makes sense now I know what λ means

So you don't want me to ask about a ground plane independant one then

6. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
So this would mean:

View attachment 62562

you have the length of the slope to work out what degree the phase is using cos & sin

I was going to ask how you determine where the start of the cycle is but this should be able to answer it, when you find '0' degrees, is the start

& we can determine how late or early it starts via time

I think I'm starting to see this but haven't got hold of it yet

Does that mean XA & XB / YA & YB are giving us the length of the other sides of triangle to work out degrees?

but thats a lot of faffing about unless you know where the start is, what am I missing

Last edited: Mar 23, 2012
7. ### cowboybobWell-Known MemberMost Helpful Member

Joined:
Oct 22, 2011
Messages:
3,052
Likes:
479
Location:
James Island, SC
I knew you would...

The first thing to consider is that the Earth (as in planet) is considered the ultimate ground, or if you will, the perfect zero potential. That is, any potential NOT zero is referenced to earth (ground).

This is true for any potential in wires, antennae, clouds, YOU, etc..

Now, take something "electrically" isolated from ground (Space station, airplane, handheld radio, etc.). In order for a radio to work, for instance, especially in transmitting mode (and to a lesser but not insignificant way, receiving), there needs to a ground as part of the system. And, in most cases, the more ground, the better. For convenience, this is often called the "ground plane" when speaking of electromagnetic wave transmission.

Take, for instance a car. Rubber wheels, right?, Very nice insulation from electrical ground). Now most cars have enough steel that that can represent enough of a ground to satisfy the needs of the radio, GPS, OnStar, etc. But what of a Corvette? Not nearly as much steel, and certainly in the older ones, very poor AM and FM reception (of this I know: I had a new '69 and now have a '74). So the solution was to attach a 1/4X4X4" metal plate to the ground lead of the antenna (directly beneath it, proximity to the antenna is critial) to improve the cars radio system's "ground plane" and, therefore, performance.

There are lots of other schemes for improving a system's ground plane (radial ground leads, for instance) but the reasons for doing this are all the same.

8. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
Does that mean it's using the coax as ground?

9. ### cowboybobWell-Known MemberMost Helpful Member

Joined:
Oct 22, 2011
Messages:
3,052
Likes:
479
Location:
James Island, SC
Yes. I'll say it this way: As to where, on the scope, a sinewave cycle starts to display, the default is 0°, which is also zero time (the "Level" adjustment in the "Trigger" segment). This allows you (and best used with sine waves) to advance or retard (by time, (which, in effect, changes the Phase) of the starting point of the scope's sweep.

If you would, please tell us exactly what you did, step by step, to arrive at the posted image. I can't get a clear image in my mind.

10. ### cowboybobWell-Known MemberMost Helpful Member

Joined:
Oct 22, 2011
Messages:
3,052
Likes:
479
Location:
James Island, SC
To a degree, yes. Any conductor can act as a ground (although maybe not such a good one). Its total mass and area also affects its usefulness as a ground.

Last edited: Mar 23, 2012
11. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
I just picked a point on the wave, decided that length gives us a calculation to work out degrees, meaning we should be able to work out where in the cycle the wave was at the given point of X/Y

so I was presuming (maybe wrongly) that if DX-DY was giving us length of slope/tangent
XA/XB was giving us length of cosine
YA/YB was giving us length of sin

yes, I can see they should be the other way around to minus values giving us length

I could then use link to to twirl example round to find out degrees meaning we would know exactly at what point of cycle XY is

of course I could have jumped 5,000000000 milion steps ahead & be the first to make 2+2=7

Last edited: Mar 23, 2012
12. ### cowboybobWell-Known MemberMost Helpful Member

Joined:
Oct 22, 2011
Messages:
3,052
Likes:
479
Location:
James Island, SC
OK. If you don't mind, I'm going to recreate the demo and post it later.

13. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
Going back to the pulse, what was that for?

14. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
Which demo, for working out phase?

You could use any wave, I'm trying to learn that I need to be able to see differences on any sim now

So is there a cheat method to phase, can you divide time to work out phase difference/angle?

I have read that time affects phase & moves cycle by advancing or retarding cycle

15. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
Unfortunely for me & I presume a big relief to KISS & your good self, this is my last night of freedom, all my holiday used up now so back to working every week, starting at 7am tomorrow, meaning back to short bursts at this from now on

& relax *grin* you've earned it

16. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
Correction for post #479

1/2 λ means 1/2 wave or 1 radian

17. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
As we are up to page 50, are they limited?
Is it worth starting a new thread 'understanding basic electronics 2'

Or is it ok to continue on here?

That's me done for another evening, on the morrow guys

Last edited: Mar 23, 2012
18. ### KeepItSimpleStupidWell-Known MemberMost Helpful Member

Joined:
Oct 30, 2010
Messages:
9,970
Likes:
1,099
CBB: I think it's time to make up a quiz?

19. ### cowboybobWell-Known MemberMost Helpful Member

Joined:
Oct 22, 2011
Messages:
3,052
Likes:
479
Location:
James Island, SC
KISS, My thoughts, exactly.

I can do sims with "What's happening here" circuits and you can do the concepts/math co-joined to them. Or vice-versa.

Something like that.

I've got a feeling you're probably better at this than me, but it sounds like a fun collaboration.

CBB

20. ### cowboybobWell-Known MemberMost Helpful Member

Joined:
Oct 22, 2011
Messages:
3,052
Likes:
479
Location:
James Island, SC
Don't think there's a limit. Pretty sure they'll let us go on till we quit (hope so, anyway).

21. ### KeepItSimpleStupidWell-Known MemberMost Helpful Member

Joined:
Oct 30, 2010
Messages:
9,970
Likes:
1,099
Something like that. I still think Graham is still confused and possibly less so than at the beginning of this thread. The guy is like a baby, picking up every toy in sight and even asking for ones on the shelves. He still has a long way to go. Without math, this has been an adventure.