Can anyone point me to some relevant reading on choosing operating points when applying CCS's to small signal tubes?
I know how to read a curve chart and choose an OP based on B+, plate resistor, grid bias, etc, but I'm not sure how to go about this with a CCS. Is it as easy as figuring the current draw through the CCS, the grid bias, and letting it operate right at B+? Do I still need some resistive loading on the plate?
Backstory: have 100V B+ and was thinking about how to maximize the voltage
I know how to read a curve chart and choose an OP based on B+, plate resistor, grid bias, etc, but I'm not sure how to go about this with a CCS. Is it as easy as figuring the current draw through the CCS, the grid bias, and letting it operate right at B+? Do I still need some resistive loading on the plate?
Backstory: have 100V B+ and was thinking about how to maximize the voltage
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Choosing the operating point for a small signal stage with a CCS in the cathode is exactly the same as for a normal stage. You still put a load line based on anode load and supply rail voltage. The only difference is that you don't have to calculate a cathode resistor, just designa a CCS to give the required quiescent current - it sets the effective grid voltage to match the particular valve sample. Whether a bypassed CCS is better or worse than using a bypassed resistor is a moot point - a resistor is certainly cheaper and more reliable.
With limited supply voltage you can maximise the anode voltage by using a good anode load CCS, not a cathode CCS.
With limited supply voltage you can maximise the anode voltage by using a good anode load CCS, not a cathode CCS.
Sorry to bump an old thread but I read somewhere that depending on the cathode voltage you need to add a small B- supply? How does this work? I have a design idea but the bias voltage is 1.5V but I know that it needs at least 1.25V across it to function. Would I add a small resistor to the tail and connect it to a -5V supply?
Ballpencil seemed to have no problem understanding my prose, and he's from Indonesia. For the record "it" in this context meant "CCS" and "tail" meant the cathode.
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Somewhat mean response to someone trying to help you, especially since your post wasn't clear to me when I read it either.
Sorry not trying to be mean at all. Seeing as this is a thread about a CCS in the cathode I though it was clear enough.
We had a lecturer who was Russian, who spoke poor English with a heavy accent. Native English speakers struggled to understand him. Chinese students said they could understand him more easily than the native-English-speaking lecturers.kodabmx said:
On another occasion, I heard an engineering lecturer in a lesser university ask a class what was the most general form of the sine function. I was puzzled; the answer was obviously 'sin z', where z can be almost anything (real, complex, a matrix etc.) but that would probably have gone over their heads. It turned out that what he was looking for was 'A sin (2 pi f t + phase)', which to me as a physicist was a very particular form of the sine function but I suppose to them it was the most general one they had seen.
At this point you had not mentioned a CCS, so 'it' could not have been referring to it; I can't see the context inside your head.
'Tail' never means cathode; it means (in certain circuits only) whatever is connected to the cathode.
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