# Understanding Electronics Basics #1

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

1. ### KeepItSimpleStupidWell-Known MemberMost Helpful Member

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The above doesn't work if the resistors were 100 and 10 ohms, for example. You did catch on that if you have two identical resistors in parallel, the value is half of one of the resistors. The two resistors in parallel formula is useful sometimes, but it's just a reduction of the generic formula.

Last edited: Mar 21, 2012
2. ### Muttley600New Member

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damn your right, I'd even writen it down, I need a picture.........................dinosaurs (time goes backwards in relation to frequency) I'll even name my dinosaur Milli so when milli moves forward = less frequency, when she backs off = more frequency

3. ### Muttley600New Member

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Finally I see it that only took about two weeks it has nowt to do with V or I, they are BOTH FIXED VALUES giving us the frequency

I noted that, just gotta check his formula with diffrent values before moving FORWARDS on your new sim

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5. ### Muttley600New Member

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1/RP = 1/100+1/10

I was trying to see how this formula worked but I can't

I think I'm having a thick day today

& no your not allowed to mention I'm like this every day

6. ### cowboybobWell-Known MemberMost Helpful Member

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Which the rest of #438 deals with.

Let me know what you think.

We'll stick with this until it gels.

<EDIT> Man, these posts fly in so fast I can get WAY behind in a heartbeat...

Last edited: Mar 21, 2012
7. ### KeepItSimpleStupidWell-Known MemberMost Helpful Member

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It depends on your calculator. I like RPN notation, it keeps your calculator from being stolen. Most people can't use them.

1/100 + 1/10 if that's what you want to use. You get 0.11 on your calculator.

There should be a button called "1/x" on a decent scientific calculator. It's useful.

So once you have the 0.11, you can use the "1/x" or reciprocal button to get the answer.

Note: That you used 10 and 100 and I used 10 and 10. No way can you get the same answer if your starting with the wrong inputs. Using 100 & 10, you know the answer has to less than 10.

Last edited: Mar 21, 2012
8. ### Muttley600New Member

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I get it, KISS is simply saying divide total R value by 1 giving us 0.00909 Ohms

I'm getting there slowly.....ok, maybe very slowly but I want to make sure it sinks in

Thanks for sticking with me guys, it means more to know your not giving up on me when you can see I can't see things, but allowing me time to try & work on it before rescuing me

lol, how timely was that, just solved, then he tells me calculator will do it for me.haha

Your right, calculator does it too no ones gonna pinch it, it's on my phone, never thought I'd get to understand what all those weird buttons were for, but slowly they are making sense

Now I should have the basics, we can move onto how it all works

Last edited: Mar 21, 2012
9. ### KeepItSimpleStupidWell-Known MemberMost Helpful Member

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No, Numty. 1/0.11 =

Dividing by 1 doesn't change anything. As I said, it does depend on how your calculator works.

I'd rather (Using RPN):
Push 10
Push 100
Reciprocal
Reciprocal
+
Reciprocal

10. ### Muttley600New Member

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I'm not dividing by one, I'm dividing 1 by the total R, try it, it really works

1/110= 0.00909

Unless that's the wrong place for decimal point? Can't double check now off computer, calculator is giving me 9.09, so could be wrong

What is the reciprocal button?

Night both

Last edited: Mar 21, 2012
11. ### KeepItSimpleStupidWell-Known MemberMost Helpful Member

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How can 1/110 be 9.09? 9.09 is correct, but the calculation is 1/0.11

The reciprocal button is labeled "1/x".

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12. ### Muttley600New Member

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Morning CBB, in the middle of chores at the mo but questions raised

What is the difference between digital & analog?

Am I right in thinking R does not go below 0 into decimal places?

Second attachment not working but I take it youve changed the R value

13. ### cowboybobWell-Known MemberMost Helpful Member

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Digital control electronics is the realm of "on - off" circuits: literally. Think of a light switch: either the light is on or it's off, nothing more, nothing less.

Now think of the "dimmer" portion of the wall light controller. That's analog control electronics. It allows you to change the brightness in an infinite number of gradations, within the limits of "maximum" and "minimum", which are generally the fully on and fully off positions.

R cannot go below zero. As a matter of fact, in TINA, if you assign a zero value to a resistor (it will not allow a negative value) it'll lock up the program (division by zero generates an infinite number, which throws the program into an infinite loop which locks up the routine).

That's not to say that a resistor can't have a very, very low value, such as 0.0000001Ω. Now matter how small, it would still be more than zero.

Here it is, and you're right.

View attachment 62473

I'll post the RC controlled pulse circuit shortly.

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14. ### Muttley600New Member

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so that is a 1KHz pulse, is that right

15. ### cowboybobWell-Known MemberMost Helpful Member

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<EDIT> Actually, no. If it was a wave length of 1 second, the frequency would be 1 divided by 1, or 1Hz.

As it is, it's the pulse "width" (only a portion of the wavelength). In this circuit, the frequency is set by the trigger timing, which you can't see yet. The answer is set out below.

OK. Here we go...

Here's the pulse circuit and its setup and correct displays (pay very close attention to ALL setup options):

View attachment 62484

"Timed Switch" parameters:

View attachment 62477

"Transient analysis" parameters:

View attachment 62478

Transient analysis results (before R1 adjustment):

View attachment 62479

Transient analysis results (after R1 adjustment):

View attachment 62480

Scope analysis (for wavelength determination and, thus, frequency):

View attachment 62482

See if you can work out the frequency of the output signal. Remember the "wavelength" is the time between the start (trigger) of a wave (pulse, in this case) and the start of the next trigger.

Don't let the wave "shape" throw you. It's still a "wave".

Also note the pulse "width", which was determined by the RC circuit.

Keep in mind that the frequency was set by the Timed Switch "Period" setting.

BTW, "period" in another term used for wavelength. Yeah, I know, "not another term. CBB!!?" Yup. You'll see this tendency to use multiple terms for the exact same thing often in electronics.

BTW, it's OK to have frequencies below 1Hz.

Enjoy. Don't hesitate to play with R1 and C1 values and observe the generated pulse changes.

Last edited: Mar 22, 2012
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16. ### Muttley600New Member

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I'm glad you said no, I meant 1hz

Thanks for breaking it down into sections, it makes it much easier

Last edited: Mar 22, 2012
17. ### KeepItSimpleStupidWell-Known MemberMost Helpful Member

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For now, negative resistance does not exist. It does exist. I don't want to go there.

Resistors with negative values don't exist as far as I know.

18. ### cowboybobWell-Known MemberMost Helpful Member

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(Underlining is mine.)

True enough. But a big time water muddying (is that a word?) concept.

Graham, for the time being (and probably forever), I would suggest that you disregard this concept.

Last edited: Mar 22, 2012
19. ### Muttley600New Member

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One step at a time guys.lol
Once I get each concept we can move onto the next, just took bobby for a walk, I'll make a quick cuppa then ask more questions

20. ### Muttley600New Member

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OK, I'm going to edit this as I go, so give me time to have a play & I'll ask questions where I've left blanks
Here a pic of my sim, I've decided you've either edited your timer symbol or are using Tina

View attachment 62493

It should still be the same but double check it, I know I haven't changed R1 yet or set R2 value, I just didn't want you to think I'd gone to sleep

So where the heck did a pulse come into this so this is just the output to another component I take it

So you taught me R*C then give me something totally different

I can feel that sigh from here

ok, I set these as yours but look at my pic

View attachment 62494

ok, the only way I can get the graph to give the output you show is like this

View attachment 62497

I can see the trigger is every 4s & the pulse is every 1s but my ism looks like it has ripples where yours is smooth?

View attachment 62502

395.57ms wave length so I'm guessing 395.57KHz

shamefully pinched

View attachment 62503

Fair enough, just a signal wave

3.948-4.951 = 1.003

900k * (1u+10f) = 0.9000009

either I've worked that out wrong or we have something not accounted for?

Tel me who did this, I need words with them

I guessed that

I might but I'm sure your gonna regret giving me more

I will soon

Last edited: Mar 22, 2012
21. ### KeepItSimpleStupidWell-Known MemberMost Helpful Member

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Period is not another term for wavelength. It Muttley's head it may look like it. Period has the units of time and wavelength has the units of length. Time and length are unfortunately the "same" on your sillyscope, but period and wavelength are NOT the same entity.