I've been testing this 1,8 MHz oscillator (circuit attached) followed by a buffer. Managed to complete the adjustments probing always on point A (buffer's transistor not soldered yet).
After soldering the buffer's transistor, surprise!! found no signal in points B or C. I recalculated the bias divider with current values shown to no avail.
Finally, after replacing the transistor twice, not sure why I probed A, B & C using both points and found that as long one of the points was probing point A, I would get output signal in B (and in C as well). I swapped the points, tested both channels with independent trigger, changed to X10 and back to X1. No change.
After lifting point D in C14, I applied a 400 mV pp sine from my signal generator and got the expected output at B (and C as well).
My questions:
a) Why I get signal at the output only if a probe is on point A?
b) Accepting that the oscillator's Ic is not enough, how to actually calculate the necessary to drive the buffer appropriately? Every time I read that the input impedance is related to the parallel of R13//R14, I get lost. Sorry but the little I knew of Thevenin, Norton and God knows who, is gone. It seems that my 73 years are claiming their share on me. Cannot help much.
Could anyone explain in simple terms the most basic so I can go ahead with my calculations? Gracias for that.
After soldering the buffer's transistor, surprise!! found no signal in points B or C. I recalculated the bias divider with current values shown to no avail.
Finally, after replacing the transistor twice, not sure why I probed A, B & C using both points and found that as long one of the points was probing point A, I would get output signal in B (and in C as well). I swapped the points, tested both channels with independent trigger, changed to X10 and back to X1. No change.
After lifting point D in C14, I applied a 400 mV pp sine from my signal generator and got the expected output at B (and C as well).
My questions:
a) Why I get signal at the output only if a probe is on point A?
b) Accepting that the oscillator's Ic is not enough, how to actually calculate the necessary to drive the buffer appropriately? Every time I read that the input impedance is related to the parallel of R13//R14, I get lost. Sorry but the little I knew of Thevenin, Norton and God knows who, is gone. It seems that my 73 years are claiming their share on me. Cannot help much.
Could anyone explain in simple terms the most basic so I can go ahead with my calculations? Gracias for that.
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