Understanding Electronics Basics #1

[Muttley600]

Morning guys
What's next then, fencing still not here :-(

 

[cowboybob]

Guess it's time to get into power supplies.

Gonna challenge you here.

How about construct a simple, half-wave sim 12VDC power supply using your mains AC (sine wave) voltage?

You'll need:

1. A voltage source.
2. "step-down" transformer. Basically a 20 to 1, primary to secondary turns ratio.
3. At least 1 diode rectifier
4. A capacitor for filtering (and anything else for that purpose)
5. A DC voltage regulator, if you wish.
6. A load resistor.

We'll help as needed. Don't forget your ground(s).

Try not to cheat too much (some is OK...).

 

[KeepItSimpleStupid]

I thought "fencing" was something you did with swards, initially.

Anyway, some math terminology.

Integers or whole numbers: -1, 0, 1, 2, 3
(they don't have a fractional part, e.g. 15/32 or 1.15

Decimals: 1.25, 1.33
(They have something after the decimal point)

Rational numbers: Something that can be written as a ratio of two integers: 1/3, 1/2, 5/1
(I think 5/1 is technically a fraction, but 5 is not)

Fractions: a/b

Repeating decimals: A fraction such as 1/3 is 0.333333 where the 3 repeats forever.

Irrational numbers: The sqrt(2) and PI is an example.

Complex numbers: They have a real and imaginary part and can be written in rectangular and or polar form. They use a very wierd quantity the sqrt(-1). In math they may be denoted in the rectangular form of 5+3i, but in electronics 5+3j is used because i usually refers to current. They can be written in a polar form as well which might be 100/_30 deg.
There is a complex plane just like there is an x-y plane or graph. The i or j axis is the vertical axis.

 

[cowboybob]

"fencing" was something you did with swards

Chortle.

I bet you've waited a lifetime for this opportunity.

What a marvelous ploy on wards...

 

[Muttley600]

Back with you guys, got a call this afternoon to say fence won't be ready until Monday so got stuck into bike, radio supply sorted for now til we make a pucker power supply

Need to run through KISS number thing on computer then I'll knock sim up, sounds easy enough
Famous last words ah.......

P.S. I never cheat, honesty is one thing I really value, if I'm stuck I'll ask for help, if I make a mess of it you'll see it

 

[Muttley600]

ok, at least you'll see what I understand & what I don't **broken link removed**

I thought "fencing" was something you did with swards, initially.

no, this is the really boring type, you know. keep the dog in **broken link removed**

Integers or whole numbers: -1, 0, 1, 2, 3
(they don't have a fractional part, e.g. 15/32 or 1.15

Just numbers without anything added you mean

Decimals: 1.25, 1.33
(They have something after the decimal point)

Fine with those

Rational numbers: Something that can be written as a ratio of two integers: 1/3, 1/2, 5/1
(I think 5/1 is technically a fraction, but 5 is not)

This is where it gets interesting because I see those as fractions, but your telling me they are just relating to two different numbers right **broken link removed**

Fractions: a/b

What is that **broken link removed**

Repeating decimals: A fraction such as 1/3 is 0.333333 where the 3 repeats forever.

fine with that

Irrational numbers: The sqrt(2) and PI is an example.

Whats PI **broken link removed**

Complex numbers: They have a real and imaginary part and can be written in rectangular and or polar form. They use a very wierd quantity the sqrt(-1). In math they may be denoted in the rectangular form of 5+3i, but in electronics 5+3j is used because i usually refers to current. They can be written in a polar form as well which might be 100/_30 deg.

Now you just plain lost me **broken link removed**

There is a complex plane just like there is an x-y plane or graph. The i or j axis is the vertical axis.

I get that bit

 

[Muttley600]

2. "step-down" transformer. Basically a 20 to 1, primary to secondary turns ratio.

you cheated, you added something this is gonna be where I trip up **broken link removed** I'll give it a go thou **broken link removed**

so I have a transformer connected, well half connected, it has four connections, I'll guess then you can have a laugh

View attachment 61953

Well, it didn't take long to get stuck, I have tried a normal diode & a zenner as rectifier & I just cannot get a half wave, slight ripple at best even with taking cap right down that was after guessing how a transformer is wired up **broken link removed**

So before helping me figure this out, is it actually wired right **broken link removed**

ok, so if by any long shot I'm working this out right you've already given me lots of help here, so my 240V source should be down to 12v through transformer if I do have it wired right, so I wouldn't be getting a wave because of values, don't tell me how to do it, just if wired right

I'm not refreshing cause I don't want to see if you replied but I'll update this post, I have a wave, it was mutual inductance whatever that is, this is fun

Sorry I had to stop to eat but this is what I've got, is it what you asked for **broken link removed** values might be wrong

It's showing 2.23E-19V on multimeter so I'm guessing I didn't get there, I'm guessing it's not wired right somehow

View attachment 61954

 

[KeepItSimpleStupid]

Fractions: Just a/b where a is called the numerator and b is the denominator. The "/" can be interpreted as a division symbol.

Complex numbers: Your probably not ready for that.

PI or ∏ is an irrational number, usually taken as somthing on the order of 3.1415926. That's the amount of digits I have memorized.

Some of the uses of ∏ is the area of a circle: A=∏*r^2 or the circumference of a circle: C = ∏*d
where r is the radius and d is the diameter. The radius is just 1/2 the diameter. The circumference is the length of the outer edge of the circle.

It's also used to convert frequency to radian frequency which is 2*∏* f where f is in Hz.

 

[Muttley600]

Back off computer, I failed on sim

KISS, are you saying a irrational number is just a number broke down by division?

Your right I'm not ready for complex stuff.lol

Not even circles it seems.......sigh

 

[KeepItSimpleStupid]

Irrational, has ratio in the wording. A ratio can be something like 1 part water to 4 parts cement or 1/4.

Wikipedia has an whole article on ∏: https://en.wikipedia.org/wiki/Pi

PI is a constant all right, but not something that can be broken down into the ratio of two integers. Generally when people use it, they will use the number of digits they require. The circle thing is there too.

Note that there is a reference that PI has been computed to over a trillion digits. The point is the numbers after the decimal point keeps changing forever.

So anyway relating it to your fence problem. By knowing the volume of a cylinder formula and the size of your post and whether it is square or round and the size of the hole you need to dig you can estimate the volume of cement you will need to set the posts.

The volume of a cylinder V = ∏*r^2*h and the volume of a square post is v= (l * w)*h or for a square post 2w*h
Volume is in units of cubic cm, cubic inches, cubic yards. Except for some dumb reason, a yard of cement is just assumed to be cubic.

So, you can find the volume of the round hole and subtract the volume of the post. Then multiply the number of posts you have to set and add some fudge factor to finally end up with how many bags of cement you will need. Your estimates would be better if you actually drilled the holes rather than dug the by hand or used a "post-hole digger". Now, since I have a demolition hammer with a 4" spade on it, I'd make my holes square if I dug them by hand. If, I were doing a yard, I'd probably rent a 2-person Auger drill to make the post holes.

 

[KeepItSimpleStupid]

Your power supply needs a little work.
1) You used a zener diode instead of a regular one like a 1n4004
2) Your resistor isn't a load because one end doesn't go to ground.
3) You took the output from the wrong place. In your case you just "current limited" what the voltmeter can draw.
4) Your capacitor is way to small. Remember the 5 * R * C rule? That's the minimum value. 1000 uF/amp of current is a "rule of thumb".

 

[Muttley600]

Your power supply needs a little work.
1) You used a zener diode instead of a regular one like a 1n4004
2) Your resistor isn't a load because one end doesn't go to ground.
3) You took the output from the wrong place. In your case you just "current limited" what the voltmeter can draw.
4) Your capacitor is way to small. Remember the 5 * R * C rule? That's the minimum value. 1000 uF/amp of current is a "rule of thumb".

I did say I wouldn't cheat.lol

So that covers no 1
No excuse for 2, but I could try & say R in circuits are inline, I know it's lame but it's the best I can do, I should have known that really
3- do you mean output should have been other side of R?
4- you lost me, I thought we just put R in to get some kind of reading?

You didn't mention wires, does that mean they are ok apart from gnd for R & moving output

 

[Muttley600]

/\ Ok, you keep using a symbol that looks similar to this, what does it stand for, if it was on its side it would either stand for greater/less than but a teepee, sky's the limit?

Got to the hole bit, but there is a simpler way for holes, you dig them 18" deep, put your post in, throw 1x25kg bag of premix in & add water = post solid within 1.5hrs but i will read it properly & thank you for giving me something to relate to, it will help me understand

Wow, that's a good link

 

[cowboybob]

Sorry. Was out most of the day.

The wiring looks fine. Good job.

What is VG1's amplitude set to?

And, the transformer's primary to secondary ratio is exactly reversed. You have it 1 times 20 (step-up, 240VAC to 4,800VAC) and it should be 1 divided by 20. In other words, the value you enter into the "ratio" line of the IdealTtransformer description should be 1/20th, as a decimal.

Generally, transformer ratios are list as primary to secondary, with the primary considered the 1 of the ratio, i.e., 1/X.

 

[Muttley600]

& pray tell what amplitude answer do you require, the 0-P or the P-P
Only joking ;-) it is set at 1V or was it 2, I kept changing everything to get wave.lol
Couldn't get one until I added mutual inductance

But you are correct, I set primary as 240v thinking transformer would reduce to 12 on a 20-1 ratio
It made sense in my head

Night both

 

[KeepItSimpleStupid]

CBB:
His wiring was off with the resistor not tied to ground. Component choices are bad too. The measured voltage should be at the opposite side of the grounded end. Then there were the component choices.

LATEX is acting goofy, so I can't explain it well right now, but x^2 is equal to x * x and X^3 is equal to x * x * x. Computers use the * to denote multiplication. Computers use the ** or ^ to denote exponentiation. X^2 is read as x squared and x^3 is read as x cubed.

The x is known as the base and the 2 is known as the exponent.

Oh, and you'll find the "^" above the 6, or Shift+6.

 

[Muttley600]

Ok, so apart from wiring wrong, wrong components & wrong values, I did good ah lol it was my first go at at a sim on my own & we did have something thrown in as a new thing
Ill give sim another shot tonight
Exponent symbol makes sense, thanks for that

Morning KISS I'm back to work today til 7pm

 

[KeepItSimpleStupid]

I should be sleeping. It's like 1:50 AM here.

if you thought ∏ was nasty to handle, take a look at the article here https://en.wikipedia.org/wiki/E_(mathematical_constant) for another constant called e.

I remember having most of this stuff too. Never did really well in the classes.

 

[cowboybob]

NOTE: I wrote this last night and forgot to post it.

I didn't exactly give you an accurate "build" description. It was intentional. For my part, I've (generally...) always learned more from my mistakes (I have been married 3 times) than from my successes. Just a quirk.

Anyway.

Couldn't get one until I added mutual inductance

No need for that. Just use the "Ideal Transformer" sim.

I set primary as 240v thinking transformer would reduce to 12 on a 20-1 ratio
It made sense in my head

See above. You were correct in your thinking. This is where you learn to trust your instrumentation.

By the way, for this particular example, I'd suggest using the scope exclusively, since where we're headed is to demonstrate how filtering comes into play.

In the AM I'll post some pix of an enhanced schematic for you to play with in this regard.

 

[cowboybob]

OK. Here ya go.

Use an "Ideal Transformer" and note ratio! VG1 is a sine wave at 240 VAC.

Take special note of ALL scope settings for BOTH VF1 and VF2. Trigger is VF1

Forget the multimeter.

Note the switches.

This is an example of the effect of capacitive filtering and power supply loading.

Let me know what you think.

View attachment 61965View attachment 61966View attachment 61967View attachment 61968

These are listed in order of set up.