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Topic: Electronics formula's (Read 1 time) previous topic - next topic

FeersumEndjinn

Hi,

I'm interested in finding out what common formula's people use on a regular basis, eiether electronic or electrical.

The common ones are Ohms Law(v=IR), Watts Law (P=IV - don't know if it is actually called Watts law), potential dividers (Vout = R2/(R1+R2) xVin) etc.

Are there any other formulas that people use on a regular basis?

Many thanks in advance.

Terry King

I used R-C time constant  T=R*C  twice today...  But mostly ohm's/watt's 
Regards, Terry King  ..On the Red Sea at KAUST.edu.sa
terry@yourduino.com  LEARN! DO! (Arduino Boards, Sensors, Parts @ http://yourduino.com

FeersumEndjinn

Many thanks for that Terry.

Anyone else?

bubulindo

P = UI
T = RC
U = RI

And I think it's about it.
Knowing the voltage drops in LEDs to calculate the current going through a LED is also good to know, but I mostly don't care and go for a 1k resistor with 5V. 

Can't think of any more formulas for small electronics, since all the other more complicated deride from these. :\
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FeersumEndjinn

Bubilindo, I know the T=RC formula - please could you explain the others as they are new to me?

Regards,
Morrolan

tastewar


...
Can't think of any more formulas for small electronics, since all the other more complicated deride from these. :\


I think you mean "derive," (he said derisively...) :-)

floresta

Quote
Bubilindo, I know the T=RC formula - please could you explain the others as they are new to me?


Substitute an 'E' or a 'V' for his 'U' and they should look familiar.


Don

FeersumEndjinn

Haha, I hadn't even clicked that there were just different versions of V=IR and P=IV!

Any others?

Grumpy_Mike

1/ (2pi Sqrt(LC)) - is the resonant frequency of an LC circuit

1/ (2pi FC) - is the capacitive reactance (equivalent resistance) of a capacitor at a frequency F. Replace C with L for inductive reactance.
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johnwasser

De Morgan's laws are helpful in designing digital logic:

NOT (A AND B) == NOT A OR NOT B
NOT (A OR B) == NOT A AND NOT B

That means that even if all you have is a big pile of NAND gates (or NOR gates) you can build anything.
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Grumpy_Mike

Not so much a law as a theorem.  :) 

johnwasser


Not so much a law as a theorem.  :) 


You'll have to edit the Wikipedia article:
http://en.wikipedia.org/wiki/De_Morgan's_laws
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Grumpy_Mike

Ok looks like I will have to. A law is reserved for physical phonemna you don't talk about Pythagrous' law do you. Or perhaps you do?

cr0sh

When I went to tech school here in Phoenix, one of the things we were given as a part of our toolkit was (IIRC) a small folding "booklet" of equations for electronics, from - once again going from memory here - Graymark. I'll have to dig it up when I get home tonight...
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Grumpy_Mike

Then there is:-
Q = VC
Where Q is charge in coulombs, V is voltage and C is capacitance (in Farads)
One coulomb is the amount of charge that flows past a point in 1 second when the current is 1 Amp.

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