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Old 17th May 2011, 8:04 am   #41
ppppenguin
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Default Re: 6080 Output Transformerless Power Amp ?

Quote:
Originally Posted by Stevie342000 View Post
I thought it was related to Ohms Law.

What are the other Laws from electrical/physics point of view that I should know ......
The 2 other laws you need for simple electrical circuits are Kirchoff's laws. The Wikipedia page is overcomplicated for what you need to know. When you realise what they mean you will think they are intuitively obvious.

KCL (current law) says that the sum of currents flowing into a node on a circuit is zero. In plain language, no current escapes. In the simplest case if you join 2 resistors together the current flowing out of one is equal to that flowing into the other so the sum of currents at the node where the 2 resistors join is zero.

KVL (voltage law) says that the sum of potentials round a loop is zero. There must be no branches in a loop so consider a battery feeding a pair of resistors in series. The voltages across the resistors must equal the voltage across the battery so the sum is zero.

KCL, KVL and ohm's law will allow you to fully understand your heater problem. There is no maths involved beyond ordinary add, subtract, multiply, divide.

Thevenin and Norton are also useful, especially when considering things such as the internal resistance of a battery. Don't worry about them until you have KCL and KVL understood. http://en.wikipedia.org/wiki/Th%C3%A9venin%27s_theorem
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Old 17th May 2011, 8:09 am   #42
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Default Re: 6080 Output Transformerless Power Amp ?

Resistors in series (More resistors gives more resistance)
Rtotal = R1 +R2 + R3 etc...

Resistors in parallel (more resistors gives less resistance)
Rtotal = 1/( 1/R1 + 1/R2 +1/R3) etc..

Capacitors in parallel
Ctotal = C1 +C2 + C3 etc...

Capacitors in series
Ctotal = 1/( 1/C1 + 1/C2 +1/C3) etc..


Inductors (coils) in series (If screened or not coupling to each other)
Ltotal = L1 +L2 + L3 etc...

Inductors (coils) in parallel (If screened or not coupling to each other)
Ltotal = 1/( 1/L1 + 1/L2 +1/L3) etc..
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Old 18th May 2011, 9:16 pm   #43
Stevie342000
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Default Re: 6080 Output Transformerless Power Amp ?

Resistance laws I knew about, capacitance I always get mixed up but it is the oppostite of resistance when in series or parallel.

Valve operating theory I think I should go and read up about, any recommendations? I have the Radiotron book? Good place to start?
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Old 19th May 2011, 12:47 pm   #44
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Default Re: 6080 Output Transformerless Power Amp ?

The easiest way to remember how it works with capacitors in series and parallel, is to imagine capacitors as what they really are: two plates separated by an insulating layer. You also need to know that C = ε * A / d; where A = area of plates, d = distance between them and ε is a constant which depends on the material.

If you put two capacitors in parallel, you are increasing the area of the plates, and hence the capacitance.

If you put two capacitors in series, you are increasing the spacing between the outermost plates (the two innermost plates, being at the same electrical potential, can be ignored) and so reducing the capacitance.
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Old 19th May 2011, 9:08 pm   #45
G8HQP Dave
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Default Re: 6080 Output Transformerless Power Amp ?

Radiotron might be a bit heavy to start with. Try to get hold of Foundations of Wireless. Early editions by Sowerby, later editions by MG Scroggie. The latest editions were updated by SW Amos, but may have less about valves.
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