# Understanding Electronics Basics #1

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

1. ### cowboybobWell-Known MemberMost Helpful Member

Joined:
Oct 22, 2011
Messages:
3,052
Likes:
479
Location:
James Island, SC
Web access is still iffy. In for now.

One way to consider AC and DC together, is this:

An AC signal is presumed to vary, UP and DOWN in potential, as a sine wave, in a positive and then negative fashion, varying around ZERO volts, or GROUND.

A DC potential is, generally, a stable POSITIVE (or NEGATIVE) potential greater than (or lesser than) GROUND.

By combining an AC signal with a DC potential, the GROUND that the AC oscillates above and below is altered to the potential of the DC level.

The oscilloscope demonstrates this phenomenon.

It's 2320 your time Graham, See ya on the morrow.

2. ### KeepItSimpleStupidWell-Known MemberMost Helpful Member

Joined:
Oct 30, 2010
Messages:
9,970
Likes:
1,099
Can you grasp this:

If you had two sine wave generators (1V p-p) in series and looked at the output and vary the phase of one of the oscillators, you can vary the amplitude from 0V to 2V p-p.

3. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
Yep, I'm getting that bit now

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

5. ### Muttley600New Member

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

not until I get the sim done, need to get ready for work so will play later, have a good day guys

Edit: still trying to understand but getting nowhere fast......sigh

What is the phase? I have tried varying it on one input but it doesnt seem to change anything?

I know 500m will give me a 1v sinewave as in 500 either side of gnd

& I understand that a DC voltage will lift/lower the signal

Last edited: Feb 17, 2012
6. ### KeepItSimpleStupidWell-Known MemberMost Helpful Member

Joined:
Oct 30, 2010
Messages:
9,970
Likes:
1,099
Phase is in degrees, so try 0, 45, 90, 180, 270

7. ### cowboybobWell-Known MemberMost Helpful Member

Joined:
Oct 22, 2011
Messages:
3,052
Likes:
479
Location:
James Island, SC
OK. Site back up. YEAH!!

I'll make a circuit w/ 2 AC sources so phase can be demonstrated.

Manana.

8. ### KeepItSimpleStupidWell-Known MemberMost Helpful Member

Joined:
Oct 30, 2010
Messages:
9,970
Likes:
1,099
In order to see phase on a scope, you can't use auto-trigger. You do need to display two generators simultaneously. Or the result and one generator. One generator has to be reference.

You can see the effect with an AC voltmeter.

9. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
I'll have a play with phase again later, as site was down yesterday I was reading up on AC, correct my understanding where it is wrong please
In DC you set the voltage on battery for sim, that's it.
In AC, Ampitude (p-p) is the voltage, so there's no direct voltage setting like DC, Ampitude/frequecy & phase all come under the wave setting.
We can add DC to lift or lower the AC signal called bias dependant on -/+
We can convert an AC signal into a DC signal with a full wave rectifier

Hers what I found interesting with AC, because it moves both directions in travel, hence we get a - side & a + side, only the + is real power, the - side is energy that returns that cannot be used by load but has to be accounted for in circuits as it is present, so the negative side can be used for the mag in inductors while the + side is running on the coil as real power, but the - side is being used to delay it (phase-duty of wave cycle) I take it without reading back that was for voltage?
A similar story for caps but with current, so the - side is where we are getting all this heat from.

Hopefully you can help my clean up my understanding, but I'm a bit further forwards, more importantly I think I now understand how inductors/capicitors work, that's two components down, still need to understand how transistors work but I feel goooooood

Morning to you both when you get up

Last edited: Feb 17, 2012
10. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
Need to work out how to get 2 channels on sillyscope now

11. ### cowboybobWell-Known MemberMost Helpful Member

Joined:
Oct 22, 2011
Messages:
3,052
Likes:
479
Location:
James Island, SC
View attachment 61207
Yes. Very good.

Yes, but an emphatic no.

BOTH "swings" (positive AND negative) of the AC signal represent power. Any change in potential away from ground is energy that can be used or observed. As you say, it is merely going one direction or the other in the circuit.

Now, If you rectify the AC (with one diode), then yes, 1/2 of (either the positive or negative swing) of the signal is blocked. So, in this case, 1/2 of the power is eliminated. However, in the case of a Full wave rectifier arrangement, both swings are utilized.

Morning, BTW...

Check this out...

View attachment 61205 and this View attachment 61209 This too View attachment 61211

(Note slight reduction in amplitude of rectified signal: this is due to internal resistance of the diode).

Last edited: Feb 18, 2012
• Like x 1
12. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
going to need to clarify this bit, I understood it to be 2 lots of power, one could power load & one couldn't, but it could be used for components if that makes sense.

so if you flip wave over into DC it is stable & cannot power components, hence having to turn DC back into AC to deal with then flip back to DC

Does that make sense, please carrying on correcting me

totally understand this, simplified by diagrams, great job

Feel free to show me how to swop wave over while I put new sim together

It must be sinking in, on second sim, I automatically changed it to 5m on time line

Last edited: Feb 18, 2012
13. ### cowboybobWell-Known MemberMost Helpful Member

Joined:
Oct 22, 2011
Messages:
3,052
Likes:
479
Location:
James Island, SC
Power is there, irrespective of the direction of flow or its potential (+ or -). I say again: Power is there, irrespective of the direction of flow or its potential (+ or -).

DC is also power. DC makes your bike's lights light, relays close, iPhones works, etc... The whole business of converting DC to AC and back to DC is an electronic method to "buck" (reduce) or "boost" (increase) a voltage (AC or DC). This is just easier to do with AC.

Again, ANY voltage GREATER than (or LESS than) zero is a form of energy (AC or DC), and will do work.

(My emphasis)

Last edited: Feb 18, 2012
14. ### KeepItSimpleStupidWell-Known MemberMost Helpful Member

Joined:
Oct 30, 2010
Messages:
9,970
Likes:
1,099
I have to interject, the concept of negative power.

Positive power is power dissapated.
Negative power is power generated otherwise...

If you had a 10 MW generator and 1 million customers consuming 10,000 W
10 MW = 1000 * 1,000,000
0 = -10MW + 1000 * 1,000,000

or
Power consumed = power generated

15. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
Yep, get that bit
This is where I got my idea of useable power for load & power for components

& that bit

& that bit

I was trying to do this, maybe jumping ahead of myself

I was jumping ahead weren't I, carry on

16. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
CBB so what does that mean in english KISS

Last edited: Feb 18, 2012
17. ### ericgibbsWell-Known MemberMost Helpful Member

Joined:
Jan 4, 2007
Messages:
21,240
Likes:
645
Location:
Ex Yorks' Hants UK
hi,
This Thread has drifted well off the '12DC' topic, it would be a good idea to start a new Thread with an appropriate Title/s, this would help members to identify the Topic/s under discussion.

Moderation. E

18. ### cowboybobWell-Known MemberMost Helpful Member

Joined:
Oct 22, 2011
Messages:
3,052
Likes:
479
Location:
James Island, SC
Graham,

Eric's right.

But this is your thread. I'll go to whatever new one you make.

Last edited: Feb 18, 2012
19. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
Shall I put new thread for understanding basics then?
& keep this one for the project
Easy on either way, it's all the same thing to me but it is turning a into a lot of pages, think its a bit much to ask any mod to try & sort out the different bits so far.

Does it need to go under 'general elec'

Could a mod please pull this from post #590 onwards & put it where it is meant to go under title 'Understanding Basics'

Thanks
Graham

While we wait, where were we, just had nice walk in countryside with bobby, no, that's not it is it, you were just about to carry on explaining where/what I had misunderstood & carry on telling me about AC

You prob see it differently to me at the moment as I'm just seeing this as playing with waveform variations

Moved: Moderation,E

Last edited by a moderator: Feb 18, 2012
20. ### Muttley600New Member

Joined:
Jan 16, 2012
Messages:
681
Likes:
5
Location:
Worcestershire, England
Wow, that was quick, I thought it would take ages

Thank you Eric
Graham

Last edited: Feb 18, 2012
21. ### KeepItSimpleStupidWell-Known MemberMost Helpful Member

Joined:
Oct 30, 2010
Messages:
9,970
Likes:
1,099
Just jumping on the train again.