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



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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...) :-)


As you probably noticed, I'm not a native speaker. Thanks for the heads up. :)
Eu não sou o teu criado. Se respondo no fórum é para ajudar todos mediante a minha disponibilidade e disposição. Responder por mensagem pessoal iria contra o propósito do fórum e por isso evito-o.
Se realmente pretendes que eu te ajude por mensagem pessoal, então podemos chegar a um acordo e contrato onde me pagas pela ajuda que eu fornecer e poderás então definir os termos de confidencialidade do meu serviço. De forma contrária toda e qualquer ajuda que eu der tem de ser visível a todos os participantes do fórum (será boa ideia, veres o significado da palavra fórum).
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).

raron

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

Small typo there, so just for completness sake: For inductive reactance the formula is the reciprocal (with regards to capacative reactance); XL = 2pi FL.

Since nobody have mentioned it, calculating resistance of resistors in parallel is also handy:
R = R1*R2/(R1+R2)

Personally I never use the above form, I like the reciprocals variant as it is simpler with more than 2 resistors:
1/R = 1/R1 + 1/R2 ... + 1/Rn

Same goes for capacitors in series btw:
1/C = 1/C1 + 1/C2 ... + 1/Cn

While capacitors in parallel just adds up (like resistors in series, so they are kind of opposite)
C = C1 + C2 ... +Cn

floresta

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Personally I never use the above form, I like the reciprocals variant as it is simpler with more than 2 resistors:
1/R = 1/R1 + 1/R2 ... + 1/Rn

Same goes for capacitors in series btw:
1/C = 1/C1 + 1/C2 ... + 1/Cn


If you have a calculator that uses RPN (Reverse Polish Notation) these versions are especially easy to implement.

Don

raron

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If you have a calculator that uses RPN (Reverse Polish Notation) these versions are especially easy to implement.

Ok. I never had one of those. But I do
(R1-1+R2-1)-1
which is similar I think, and pretty quick also, since there is a "^-1" button.

floresta

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(R1-1+R2-1)-1


As I see it this requires at least 6 keystrokes over and above whatever it takes to enter the resistor values.

With RPN you enter: R1, 1/x, R2, 1/x, +, 1/x  Since there is a 1/x key this gives you 4 keystrokes over and above whatever it takes to enter the resistor values.  In my experience RPN always does the job with fewer keystrokes.

Don


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