Understanding Electronics Basics #1

[Muttley600]

Thanks for your praise CBB, I'm still loving getting my head around all this

Looking forward to learning lots more, however I'm still unsure why I'm getting different readings off sillyscope & multimeter?

Will have another play after visiting parents

 

[Muttley600]

Here's a Neato circuit sim. site with various virtual circuits displaying current flows, o'scope presentations, etc. Needs Java, though.

First one up is an RLC circuit. Operate the switch in the circuit and observe how the current flow "charges" the inductor. Then open the switch and observe how the RLC portion "oscillates", with ever decreasing current (and voltage) levels as the cap discharges. VERY cool. Have fun.

This, circuit, by the way. does not translate into a working TINA schematic. It's a demo only. Matter of fact, that circuit blows TINA up...

But it demonstrates how, by pulsing (turning the juice on and off in a regulared fashion) a circuit like this, an oscillation can be maintained.

They have a whole catalog of circuits ("Index of circuit examples").

It's your fault, do you know how long I've spent playing on there **broken link removed** Great for seeing how things are actually working **broken link removed** That circuit wizard sim has that for whatever cicuit your working on, tempting to get it still, or is that cheating, although looking at sim I'd never have worked out how some of those were actually working, there was V going backwards from the output back to start, was that to let oscillation back the other way

 

[Muttley600]

I seem to be having trouble posting??
Tried to send you pm other night, tried to post on here, it keeps saying something about token expired? Both times on phone

Nora flipping.lol it's worked now, I was saying that I have just spent ages with part 2 of sim diag & couldn't post it, I'd put it inside quote label, so couldn't post, I must be having a few off days :-(

 

[Muttley600]

Anyway after counting to infinity & back again.....ok, ok, I had a smoke.lol

OP2 is actually the supply component of the whole circuit in a way, without it OP1 can't work as it is supplying VP through lead 5 via R4 to Z1&2 & also supplying VP through C3 & R3 (hence the drop to 16.6mV on lead 2 of OP1) with C1 altering phase.
So OP2 is doing two jobs but this time is actually working as an amplifier as well

Just need to work out what C4 is doing now & why C4 & C3 have different values with same VP unless it is just a timing thing?

Summing up, this all means that the Z line is for ampitude of wave, OP2 is main supply & VF2 - output while OP1 is output for VF1, caps are to supply steady V (length of signal over time)

How's that?

 

[KeepItSimpleStupid]

The token expired error happens when you haven't refreshed the page in a while. e.g. You went to sleep with the page open in the browser and then tried to post something. Save your work and refresh the page. Unfortunately it won't work well if your trying to post a gazillion attachments.

 

[KeepItSimpleStupid]

C4 is there to help keep the OP amp stable. It reduces the gain significantly at high frequencies. OP amp stability is a real world thing. Unity gain stable is another real world thing. Not all OP-amps are stable at a gain of 1.

Just like you have been having lots of fun learning, so have I. Today I finished my spreadsheet and sized a dry well for drainage applications.
I forgot something the first time around with something I already have together. I need "silt filtering". This design has to have it in the design.
Retrofitting the first project could get very messy. A silt fence is working for now.

 

[Muttley600]

The token expired error happens when you haven't refreshed the page in a while. e.g. You went to sleep with the page open in the browser and then tried to post something. Save your work and refresh the page. Unfortunately it won't work well if your trying to post a gazillion attachments.

There were no attachments on either but your saying it's a time thing, I can spend ages replying on computer but phone doesn't like long replies.

Thanks for helping with C4 KISS, couldn't get that one but what you say makes sense

Was it you or CBB that had the well, now that really is relating electrickery to water.lol
Hope it's gone WELL ...........sorry couldn't resist but what is a silt fence?.....Doh, basically some kind of board or filter so well doesn't backfill itself with silt
There seem to be wells mentioned a bit, I take not everyone is on mains water, or if your now using yours as drainage, youve recently gone into mains

So how am I confusing sillyscope & multimeter readings then? I thought scope would show same reading?

 

[KeepItSimpleStupid]

Silt Fence: https://www.ehow.com/about_5112653_silt-fencing.html

In the image, the yellow lines are underground. The discharge is 30 feet to the right through a pop-up.

The Red lines are surface water. The fence keeps the dirt from falling in the grate and hopefully it's temporary. The corrugated pipe is also temporary.

 

[Muttley600]

Are you having some groundwork done then KISS

 

[cowboybob]

So how am I confusing sillyscope & multimeter readings then? I thought scope would show same reading?

Don't forget that the multimeter is designed to register the RMS (Root Mean Square) of the Peak to Peak (PP) value that the scope is showing, i.e., 0.707 X PP. If you have an an AC voltage showing 2 VAC PP on the scope, the multimeter will register 1.414VAC.

there was V going backwards from the output back to start, was that to let oscillation back the other way

Yes. And to "sample" the output, sending it back to the beginning (slightly out of phase) to help maintain oscillations.

An OpAmp is designed to allow its output to either source (provide) or sink (receive) current. Those little dots moving around in the wires of the circuits are current. Below is the schematic for a TI LM741 OpAmp (fairly typical):

View attachment 61846

Plain old components.

Imagine what an Intel Dual-Core processor schematic looks like: literally millions of transistors and other components. And mostly designed to simply turn on or off. VERY rapidly - billions of times per second.

KISS. Were you using the well for potable water, or just yard watering purposes?

 

[KeepItSimpleStupid]

I did the design and the digging myself, but I just have this silt glitch. It should get better if I get grass to grow, but there is basically dirt to the left of the drain. In front of the drain is the neighbor's driveway. The section to the left isn't done. A 30' foot long by 18" deep x 10" wide trench needs to be dug with two more catch basins upstream. I'm designing another system where the purpose is capture and inject. This is capture and divert.

 

[cowboybob]

Sort of a French drain thing? We use those a lot around here (coastal SC).

 

[Muttley600]

man, I need a cuppa, I think I'm about all lessoned out **broken link removed**

I now know ( ) means you do this part of the sum first

when I see X = this is just the value of the notation

A number or value over each other with a line means divide

3
10 means 10x10x10 (or add 3 zeros for the power of 10) & the little number above is called the exponent & '0' means 1

also the order of notations & I'm guessing I still have a mountain to climb **broken link removed** but I will get there


I'm back for some light relief & I see CBB has answered my query, that involves getting my head around numbers **broken link removed****broken link removed**

I'm just going to grab that cuppa & come back & figure out what I'm doing with now

What a day **broken link removed**

& how does KISS manage to get his sums looking like sums?, site has corrected everything to the left

 

[Muttley600]

Don't forget that the multimeter is designed to register the RMS (Root Mean Square) of the Peak to Peak (PP) value that the scope is showing, i.e., 0.707 X PP. If you have an an AC voltage showing 2 VAC PP on the scope, the multimeter will register 1.414VAC.

Going to have a look at this now

So are you saying MUTT41 is showing signal as 500mV as measure of each sqaure on scope = 4V x 12.6

How are you relating 0.707, of a V, mV? otherwise I'm getting it working out to 5.04V which might be right with bit of discrepancy on the 4V rough guess, means I'm measuring one of the 5V battery signals

I've just learn't that you can disable each signal on screen of sillyscope *grin* they say simple things please simple minds.lol

Below is the schematic for a TI LM741 OpAmp (fairly typical):

View attachment 61846

Plain old components.

Amazing, so by me wanting to know the basics, you are giving me a great understanding **broken link removed**

I really needed that **broken link removed**

Lets get sim back up running again & see whats what

ok, looking at MUTT48, how do I get the exact measurement on sillyscope, I know the dy/dx are relating to a derivitive

& how do you type below your attachment? Think I get it now, I'm looking at YA & YB which is -1.94 & 1.9 = 3.84 x 12.6, no I'm still not there, edit: or if I use .384 x 12.6 I get 4.8384 which could be because of resistance in circuit, does that mean fron VS1 through OpAmp to C1 the circuit has actually lost 0.1616V in resistance?

That's all total tosh isn't it, I have a gut feeling, why would I have had to make 3.84V .384V

Edit: I'm moving the decimal point on the wrong thing aren't I, I should be moving it on the 12.6 not the 3.84 because 1V = 1000mV
So 0.126 showing on multimeter x 3.84 showing on sillyscope = 0.483mV so 500mV display was near perfect
Man, imstruggling with this decimal place on mV, if there are 1000mV in a V 12.6mV should read as 0.0126 shouldn't it? But that makes it all wrong

Morning CBB

Right, I've definately made my mind up that each square on scope represents 500mV & we do indeed have a 3.84VAC PP signal

I need to understand math better cause I'm getting nowhere fast here, it is just making me realise how thick ~I really am

 

[cowboybob]

Afternoon, Graham.

I have been in error describing RMS. You might want to read this.

From the scope display, I see 4VAC PP (8 X 0.5V per graticule vertical, most negative swing to most positive swing) OR, taking half of PP you get 2VAC "zero to peak". So this is 2 X 0.707, or 1.414 VAC RMS. See below.

View attachment 61883

Sorry for the misleading (read, WRONG) definition of RMS.

Although, after reading the above link, you'll see that there are several definitions of RMS.

And yeah, decimals can give you fits.

CBB

 

[Muttley600]

Ok, this is my final attempt
If we are talking about RMS, I do this:
12.6x12.6x12.6 = 2,000.376mV
Converting to V = 2.000376 = 2.0VAC PP which isn't right.....sigh

 

[Muttley600]

Hiya CBB, does that mean I'm not going mad.lol

Thanks for saving my sanity, I can't open link on phone but that still wouldn't give me the 3.84V I'm looking for would it, it would be just over 4V & I'm getting just under, shouldn't they tally

 

[Muttley600]

https://en.m.wikipedia.org/wiki/Alternating_current

Strange as it seems, those odd looking sums are starting to make sense.EEK!
I think it's getting a bit easier to relate to them now

I don't know what the squiggly tick means but if I divide VPP by that symbol on calculator it gives near enough the right answer, then 12.6 squared is working out right

So that means that squiggly tick is just dividing by two, but the line between VPP is telling you to do that anyway isn't it?

But this also means I can now relate readings between multimeter & sillyscope.......I got there in the end

So which point of my learning will I catch up with all the strange symbols, they don't seem to be in algebra I've covered so far, only letters. Are they in calculus?

& yes, I noticed that different waveforms have different exponents, shouldn't have used that word cause KISS will pick up on it, it's just the way I've related to algebra.
An exponent is a multiplication but is undone by a division....

 

[cowboybob]

I don't know what the squiggly tick means

Neither do I. Can you provide a "snip" of the symbol?

 

[Muttley600]

Neither do I. Can you provide a "snip" of the symbol?

It's one of these with a line to the right across the top of it - √
In link under 'mathematics of AV voltages'

Seems it is called the 'crest factor' & can mean a number of things but my basic understanding still seems to work, this is like learning a whole new language