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Although I convinced myself otherwise at the time, I tried learning through equations when I was in grade school and didn't learn jack. It's best to seek out a tutorial page like or something more comprehensive like a Shaum's Outline book.
* Resistance (R) is given by doing some manipulation of 0hm's Law. Since V= I*R, dividing both sides of the equation by "I" yeilds R = V/I.
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* Impedance (Z) is a combination of resistance (a real number) and reactance (an imaginary). Given that, you can expand 0hm's Law for more generality by saying: V= I*Z, or Z = V/I.
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* Because impedance is a complex number, there are actually several "types" of power (true, reactive, and appearant). In a DC circuit, we can stick to true power by saying: P = V*I -or- P = I²R -or- P = V²/R. All three are equivalent because of the V=I*R rule.
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* Charge (Q) is a measure of how many electrons occupy some finite space. Because charge is important while dealing with capacitors, we can say:
Capacitor Charge (Q) = Capacitor Voltage (V) * Capacitance (C)
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* Capacitance and Inductance are where Calculus comes into play. The capacitor voltage and current is always:
Vcapacitor = 1/C ∫ i(t) dt + Vinitial (integral limits: 0 to t)
Icapacitor = C * (di/dt)
The actual capacitance of a capacitor is set by the plate area, the plate spacing, and the dielectric material.
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* Inductors have a similar pattern:
Vinductor = 1/L ∫ v(t) dt + Iinitial (integral limits: 0 to t)
Iinductor = L * (dv/dt)
The actual inductance of an inductor is set by the number of turns, the radius of the coil, the core material, and the inductor length.
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* Transistor Current Gain is signified by β and α. (β is sometimes called "Hfe"). Beta is the ratio of collector current to base current. Alpha is the ratio of collector current to emitter current. So to sum it up: Beta = Ic/Ib. And Alpha = Ic/Ie. Also, the two are inter-related by:
α = β / (β + 1)
β = α / (1 - α) <--- Double-check me on this one
...it's important to note that β and α only describes the transistor and not the whole amplifier. Also, the two are not constant, and β tends to shrink and as the transistor saturates and begins carrying its maximum current.
If you go to a university or college book store, or even some regular book stores, there are what are called "crib sheets" or "cheat-sheets". They are laminated cards, 8 1/2 x 11 inch, ti fit in a 3 ring binder, they cover many topices, and are absolutely crammed front and back with data, including formulaes, charts, etc.
I don't remember who made the ones I have seen, but here is something similar:
I have several QUICK STUDY laminated cards- by Bar Charts Inc, Boca Raton, Florida, USA. Excellent with one "however" - useful as a quick reference if you understand the material. It might help as a supplement to other study materials or a good mentor but alone I think they'd create more problems than they solve. I suppose the important point is that if it helps you then it's the right tool.
* Resistance (R) is given by doing some manipulation of 0hm's Law. Since V= I*R, dividing both sides of the equation by "I" yeilds R = V/I.
--------------------
* Impedance (Z) is a combination of resistance (a real number) and reactance (an imaginary). Given that, you can expand 0hm's Law for more generality by saying: V= I*Z, or Z = V/I.
--------------------
* Because impedance is a complex number, there are actually several "types" of power (true, reactive, and appearant). In a DC circuit, we can stick to true power by saying: P = V*I -or- P = I²R -or- P = V²/R. All three are equivalent because of the V=I*R rule.
--------------------
* Charge (Q) is a measure of how many electrons occupy some finite space. Because charge is important while dealing with capacitors, we can say:
Capacitor Charge (Q) = Capacitor Voltage (V) * Capacitance (C)
--------------------
* Capacitance and Inductance are where Calculus comes into play. The capacitor voltage and current is always:
Vcapacitor = 1/C ∫ i(t) dt + Vinitial (integral limits: 0 to t)
Icapacitor = C * (di/dt) No, i = C dv/dt
The actual capacitance of a capacitor is set by the plate area, the plate spacing, and the dielectric material.
--------------------
* Inductors have a similar pattern:
Vinductor = 1/L ∫ v(t) dt + Iinitial (integral limits: 0 to t)
Iinductor = L * (dv/dt) No, v = L di/dt
The actual inductance of an inductor is set by the number of turns, the radius of the coil, the core material, and the inductor length.
--------------------
* Transistor Current Gain is signified by β and α. (β is sometimes called "Hfe"). Beta is the ratio of collector current to base current. Alpha is the ratio of collector current to emitter current. So to sum it up: Beta = Ic/Ib. And Alpha = Ic/Ie. Also, the two are inter-related by:
α = β / (β + 1)
β = α / (1 - α) <--- Double-check me on this one
...it's important to note that β and α only describes the transistor and not the whole amplifier. Also, the two are not constant, and β tends to shrink and as the transistor saturates and begins carrying its maximum current.
LOOK WHAT YOU NEED IS A REFERENCE DATA BOOK mine is for radio a nd electronics for engineers and it is old by INTERNETIONAL TELEPHONE AND TELEGRAPH CORPORATION. It has anything you want in there from the size of wire to screw size to KLYSTRON ,LAPLACE TRANSFORM you name it. mine is forth edition pay the money and it will stay with you forever. do you know the sign of a good engineer is a GUY THAT KNOW WHAT BOOK TO GO TO FIND THE ANSWERS. And another book if SYSTEN ANALISYS by philip & cutler.you learn these 2 books you got it.
The gain (Hfe) of transistors listed on their datasheet is an approximation. Some transistors can have up to 200% of this value, even "complimentary pairs" for use in push-pull amplifiers (where the gain needs to be a pretty close match). Don't trust the datasheets. Adjust the values of your emitter and/or collector resistors for the appropriate gain, and don't bypass the emitter resistor with a cap for extra AC gain, because you won't know for sure what that gain will be.
Go to the site that DigiTan suggested earlier. Navigate to the forums. (The link is in the top right of the first page.) Navigate to the first sub-forum, General Electronics Chat. Then check out the first link titled Electronics AC/DC + Logic Cheat Sheets (Final Edition).
You can find a circuit formulas cheat sheet in the first post there.
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