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« on: May 25, 2011, 06:47:52 am » |
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.
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Red Sea, Saudi Arabia
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« Reply #1 on: May 25, 2011, 06:55:30 am » |
I used R-C time constant T=R*C twice today... But mostly ohm's/watt's
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« Reply #2 on: May 25, 2011, 07:06:47 am » |
Many thanks for that Terry.
Anyone else?
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'round the world...
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« Reply #3 on: May 25, 2011, 08:18:16 am » |
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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Nota também que eu não me responsabilizo por parvoíces escritas neste espaço pelo que se vais seguir algo dito por mim, entende que o farás por tua conta e risco.
Dito isto, mensagens pessoais só se forem pessoais, ou seja, se já interagimos de alguma forma no passado ou se me pretendes convidar para uma churrascada com cerveja (paga por ti, obviamente).
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« Reply #4 on: May 25, 2011, 08:32:15 am » |
Bubilindo, I know the T=RC formula - please could you explain the others as they are new to me?
Regards,
Morrolan
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« Reply #5 on: May 25, 2011, 09:00:44 am » |
...
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...) :-) |
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« Reply #6 on: May 25, 2011, 09:07:12 am » |
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 |
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« Reply #7 on: May 25, 2011, 09:13:50 am » |
Haha, I hadn't even clicked that there were just different versions of V=IR and P=IV!
Any others?
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« Reply #8 on: May 25, 2011, 11:49:36 am » |
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. See filter discussions in:- http://www.thebox.myzen.co.uk/Tutorial/PWM.html |
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« Reply #9 on: May 25, 2011, 12:16:32 pm » |
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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« Reply #10 on: May 25, 2011, 12:19:35 pm » |
Not so much a law as a theorem.  |
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« Reply #11 on: May 25, 2011, 12:46:28 pm » |
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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« Reply #12 on: May 25, 2011, 04:49:46 pm » |
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?
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« Reply #13 on: May 25, 2011, 05:03:21 pm » |
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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« Reply #14 on: May 25, 2011, 10:24:28 pm » |
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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