Microcontroller newbie

[AtomSoft]

Capacitor conversion help:
https://www.justradios.com/uFnFpF.html

1F = 1000 mF = 1,000,000 μF = 1,000,000,000 nF = 1,000,000,000,000 p

 

[ArtemisGoldfish]

The RC time constant is R * C. So, if you use a 10Kohm resistor and a 20pF cap, you'll get an RC time constant of 200ns, and a frequency of 5MHz.

 

[AtomSoft]

Yeah lol im no math guru so i was lost lol

t = R * C

and

f=1 / T

t = time in Seconds
R = resistance in Ohms
C = capacitance in Farads
f = frequency in Hertz

You can use google like:

20 microfarad to Farad

to convert uF to F...

uF (microfarads)
pF (micromicrofarads) (picofarads)
nF (nanofarads)

 

[Pommie]

The highest speed would be with a 3k resistor and a 20pf capacitor which would have a RC constant of 3x10^3 x 20x10^-12 = 0.00000006 seconds. This would give a frequency of 16MHz which seems exceedingly high. Maybe someone should check my figures.

Mike.

 

[ArtemisGoldfish]

The highest speed would be with a 3k resistor and a 20pf capacitor which would have a RC constant of 3x10^3 x 20x10^-12 = 0.00000006 seconds. This would give a frequency of 16MHz which seems exceedingly high. Maybe someone should check my figures.

Mike.

Your math is right, it doesn't exactly seem *exceedingly* high, however, it'd probably be really unstable and unreliable at that speed.

 

[AtomSoft]

The highest speed would be with a 3k resistor and a 20pf capacitor which would have a RC constant of 3x10^3 x 20x10^-12 = 0.00000006 seconds. This would give a frequency of 16MHz which seems exceedingly high. Maybe someone should check my figures.

Mike.

20 picofarads = 2.0 × 10exp-11 farads = 0.0000000002

0.0000000002 * 3000 = 0.0000006

But i am getting: 1,666,666.6666666666666666666666667

Would that not be only less than 2Mhz?

 

[AtomSoft]

i think you had this wrong:

20x10^-12

supposed to be

20x10^-11

im sure

20 picofarads to Farad - Google Search

 

[ArtemisGoldfish]

20 picofarads = 2.0 × 10exp-11 farads = 0.0000000002

0.0000000002 * 3000 = 0.0000006

But i am getting: 1,666,666.6666666666666666666666667

Would that not be only less than 2Mhz?

Oooh, your math is a tad bit off.

20E-12 * 3E3 = 60E-9
1/60E-9 = 16.667E6, or 16.667MHz

Google is returning the conversion in Scientific notation, it's useful to us in Engineering notation. Here are the prefixes:
Milli (x10^-3)
Micro (x10^-6)
Nano (x10^-9)
Pico (x10^-12)

Google says 2.0 x 10^-11, which is 20 x 10^-12

 

[AtomSoft]

so google is wrong? this sux heh.. i can see your 16Mhz now. Which is cool for max. but i bet a tad unstable

 

[ArtemisGoldfish]

so google is wrong? this sux heh.. i can see your 16Mhz now. Which is cool for max. but i bet a tad unstable

Nope, google is completely right. It's just not in the format that I find terribly useful.

 

[AtomSoft]

Google says 2.0 x 10^-11, which is 20 x 10^-12

Its funny

Google :  0.0000000002
Engineer: 0.0000000002

* 3k = 0.00000006

1/0.00000006 = 16,666,666

How i the heck did i mess this up before? if they are the same. I must be tired heh its 6min to midnight here

Ill be sure to save:
Milli (x10^-3)
Micro (x10^-6)
Nano (x10^-9)
Pico (x10^-12)

 

[ArtemisGoldfish]

Its funny

Google :  0.0000000002
Engineer: 0.0000000002

* 3k = 0.00000006

1/0.00000006 = 16,666,666

How i the heck did i mess this up before? if they are the same. I must be tired heh its 6min to midnight here

Ill be sure to save:
Milli (x10^-3)
Micro (x10^-6)
Nano (x10^-9)
Pico (x10^-12)

It's helpful to use the right exponents if you use exponents on a calculator, and using exponents can really reduce the chance that you'll press 0 too many times in a very small number (or too few times).

 

[AtomSoft]

Why the heck am i getting weird values?

20*10^-12 = 0.0000000002

1 / (3000 * 0.0000000002) = 1 666 666
1 / 0.0000006 = 1 666 666

I thought i was getting 16 but heh maybe im tired ill try in the morning heh

 

[ArtemisGoldfish]

Why the heck am i getting weird values?

20*10^-12 = 0.0000000002

1 / (3000 * 0.0000000002) = 1 666 666
1 / 0.0000006 = 1 666 666

I thought i was getting 16 but heh maybe im tired ill try in the morning heh

You know, you're still messing up the number of 0's you're using. Exponents man, they're useful.

 

[AtomSoft]

im using windows calc with exponents and its giving me those numbers lol

 

[AtomSoft]

Oooh, your math is a tad bit off.

20E-12 * 3E3 = 60E-9
1/60E-9 = 16.667E6, or 16.667MHz

Google is returning the conversion in Scientific notation, it's useful to us in Engineering notation. Here are the prefixes:
Milli (x10^-3)
Micro (x10^-6)
Nano (x10^-9)
Pico (x10^-12)

Google says 2.0 x 10^-11, which is 20 x 10^-12

i get 16,666,666 only when i do:

2*10^-12 = 16mhz
20*10^-12 = 1.6mhz

Which one am i supposed to use

 

[ArtemisGoldfish]

Look at the attached pictures on my post.

 

[Pommie]

Well, the value of the capacitor is 20pF and so it is 20 x 10^-12. And, 3E3*20E-12 is around 16M. Post the calculation that produced 1.6 MHz.

Mike.

 

[gaspode42]

Jason

I think that this is a function of the way you are driving the windowz calculator. I get the same result in Unix (ubuntu) as you are if I do 20*10e-12 (because this is besing expanded to 200e-12), however if you do 20e-12*3e3 (and then do 1/x) you get the correct result. In fact I could not get in to work in Windowz at all!

Hope this helps,

Rupert

 

[Pommie]

Wow, maths is now operating system dependent.

Unbelievable.

Mike.