(03-03-2017, 11:43 AM)Nowhere-Man Wrote: The wording of a question for me is crucial. I did old exam questions on this stuff in the past and never got one wrong. I'm also choosy about textbooks and avoid classroom systems. I would start first on PNP germanium because these were the first used and current doesn't leave the N type base. It sinks current at the base. Bear in mind transistors are new to me (about 7 weeks). So, start with the basics is best, PNP first. Also with valves phase is very important and I have to apply this to semiconductors too. What is the phase of cathode anode voltage in relation to the anode load of a triode? That is with signals on the grid. What is the cathode grid phase? I need the full picture to get the details.
It's easy to figure out the phase relationship between a signal on the grid and the signal across a cathode resistor, as the grid voltages increases more current flows through the cathode resistor therefore the voltage across it increases, therefore the grid voltage and cathode voltage increase at the same time, therefore they are in phase with each other, that same increase in current causes a voltage drop across the anode load resistor which means that the voltage on the anode will reduce at the same time, in other words the increase of grid voltage results in a decrease of anode voltage, therefore the grid and anode voltages are not in phase with each other, there is now a phase difference of 180 degrees between the grid signal and the signal between the anode and ground, you now have the basics of a phase splitter because the anode and cathode signals are out of phase by 180 degrees, take that one step further and shift the anode signal by a further 180 degrees and feed it back to the grid in sufficient quantity and you now have the basics for an oscillator.
Same thinking for transistors.
EDIT: Post crossed.
Lawrence.
