Understanding Electronics Basics #1

[KeepItSimpleStupid]

I was apparently born with 7 senses instead of 5. I have the "6 th sense". The seventh is sensitive to the second derivative of barometric pressure vs. time or I know when it will rain.

 

[KeepItSimpleStupid]

The ripple gets reduced when the capacitance is greater. You saw that with the power supply filter where you changed the value of the capacitance and saw the resulting ripple decrease when you increased the capacitance.

 

[Muttley600]

Log10(x) is easy. It's just the exponent.

Cool, I get that

Any number raised to the 0 power is 1. It's just a definition.

& I know that (couldn't of said that a few weeks ago)

LOG base 10 of 25 is 1.397940009
LOG base 10 of 50 is 1.698970004 which is a number between 1 and 2.
LOG base 10 of 90 is 1.954242509
LOG base 10 of 99 is 1.995635195 (nearly 2)

but where did this come from, I've found LOG on calculator & it agrees with you, how is it working that out?

The LOG function is not defined for 0 or negative numbers.

I'll note this once I understand it properly

The graph is read almost the same way as a linear graph. In the graph above there are 10 divisions between 1.00M and 10.00M. Finding the value between tick marks is called interpolation and that's much harder.

ok, lets lay the base before putting the topping on **broken link removed**

 

[Muttley600]

RC is just R * C or the product of R & C.

i.e. R = 10 M ohms, C = 1 uf
RC = 10,000,000 * 1E-6

I so nearly understood that, until the last bit **broken link removed** so the caps cause those E numbers to come up, can you expand on that bit for me unless we're heading that direction anyhow **broken link removed**

 

[Muttley600]

I was apparently born with 7 senses instead of 5. I have the "6 th sense". The seventh is sensitive to the second derivative of barometric pressure vs. time or I know when it will rain.

Cool, can you tell if it will rain in England & when, would be very useful for booking time off in advance for bike rideouts **broken link removed**

 

[Muttley600]

The ripple gets reduced when the capacitance is greater. You saw that with the power supply filter where you changed the value of the capacitance and saw the resulting ripple decrease when you increased the capacitance.

ahah, so that's what your calling ripple, the curve **broken link removed**

 

[KeepItSimpleStupid]

We havn't covered scope with math functions, scope with cursor and Xc, right?

The scope with a cursor you can play with on the sim.

See the specifications section here https://www.tek.com/datasheet/digital-storage-oscilloscopes-0 under automatic measurements and cursors. This is a spec sheet of a real scope of today's technology.

Xc I pulled out of a hat. For that we have to take a math detour and learn about vectors and right triangles.

 

[KeepItSimpleStupid]

We covered the E numbers, but I guess you slept through the lecture.

1e-1 = 0.1, 1e-2 = 0.01, 1E-3 = 0.001

1 uf is 1 microFarad and you remember the nano, micro, pico etc. stuff now? micro is 1e-6.

So, 10 uf = 10 * 1e-6 or the text books show it as (Latex is still broke)

 

[Muttley600]

I don't really want to diverge into a discussion about db yet, but some caveats are that db has to have a reference level. In electronics, there are both voltage and power references.

dbV is db referenced to 1 volt.
dbmV is referenced to 1 mV

db in CBB's example is referenced to gain or amplification. 0 db is no amplification. .

So I have always thought of db as relating to sound, but it seems like your telling me........aaahhhhhh, frequency, so is this going to lead to strength of signal of kinds, hence amplification

 

[KeepItSimpleStupid]

ripple = usually an unwanted AC component. You want 5 V DC, but not 5 V DC that varies from 4.8 to 5.2 V over time. The variation is ripple. It's usually expresed as an RMS voltage in % of the desired output like 0.1% RMS or say 10 mV p-p.

 

[KeepItSimpleStupid]

Notice the db levels again here: https://en.wikipedia.org/wiki/Sound_pressure as it relates to sound of various things.

 

[Muttley600]

Xc I pulled out of a hat. For that we have to take a math detour and learn about vectors and right triangles.

ok, maybe we can leave that until I catch up on math a bit **broken link removed**

 

[Muttley600]

We covered the E numbers, but I guess you slept through the lecture.

I must of, but thanks, that makes a lot more sense than thinking I'm getting an error reading, this is all starting to come together now isn't it **broken link removed**

I've caught up **broken link removed**

 

[Muttley600]

ripple = usually an unwanted AC component. You want 5 V DC, but not 5 V DC that varies from 4.8 to 5.2 V over time. The variation is ripple. It's usually expresed as an RMS voltage in % of the desired output like 0.1% RMS or say 10 mV p-p.

That makes a lot of sense & I take it the cap can filter that ripple out or is that after cap filtering

 

[KeepItSimpleStupid]

For now, Xc is the magnitude of the capacitive reactance at one particular frequency and it has units of ohms. It ACTS SOMEWHAT LIKE a resistor at the single frequency it is computed at.

 

[KeepItSimpleStupid]

In general, the larger the capacitor, the smaller the ripple. Not always true, but at this level it is.

 

[Muttley600]

For now, Xc is the magnitude of the capacitive reactance at one particular frequency and it has units of ohms. It ACTS SOMEWHAT LIKE a resistor at the single frequency it is computed at.

So your saying it is where the dot of a curve is at a given point in time (Xc) is on the graph in relation to V verses frequency

Are we saying frequency is just one wavelength & we measure that over time to pinpoint accuracy **broken link removed**

So the radion is to measure the phase/cycle of wave & a derivitive simply gives you a slope on these graphs

edit: the log graph has a base of 2.718281828 above X hence: 10 of 25 would mean multipling 2.718281828 25 times by itself but the calculators do that for us & this system has been designed to do away with what would feel like an impossibley boring math value by hand

How am I doing?

 

[KeepItSimpleStupid]

Nope. It has to wait. Did you see an axis labeled "ohms"? I didn't.

What I can say is that when you looked at the graph of the voltage across the capacitor as a function of frequency, the source voltage "divided" between the resistor and the capacitor. Xc(f) is the effective resistance at every frequency. Xc(f) means Xc is a function of f (frequency).

Xc would be the value of resistance that the capacitor would have to exhibit to cause the corresponding drop in voltage at each frequency.

 

[Muttley600]

Wow, this was well worth staying up all night for, just stopped for smoke & cuppa, back in ten

 

[Muttley600]

so you work out frequency on a circuit by simply dividing V = R by cap value

so if you were planning a 13.7V-8A circuit, you would need: 1.7125 R

so this is where I get tied in knots by that blinking decimal point, is that 1.7K

I was going to work out a R & cap value but I take it that 1.7125 has to be distributed amongst all other components in the circuit

we are now saying once you have your intial layout that by altering the cap value at a given V will give you any frequency you plan for

That seems too easy, but then I can't even get the decimal point right **broken link removed**

so how about inductors, they were sometime about holding I over time weren't they, for what purpose would you want to increase resistance against I

so by knowing this I get an interference free circuit theorectically, unless I'm unlucky enough to pick a frequency that clashes on bike