Had nothing to do with bias. We had "dynamic bias", meaning bias was only applied when a drive signal was detected by a Ge diode and transistor. Else the tube consumption per year would reach fiscally unfathomable levels, at least for a student.
Problem was that we squeezed them out real hard. For example an amp with five H-deflection tubes for color TVs delivering a sustained 1200 watts of raw RF output power. No joke, this was measured with a calibrated Bird wattmeter and was legit back then in Germany. It blew up my antennas numerous times. The loudest bang was a balun where the T200 Amidon core was literally gone afterwards. Shoulda stacked two cores but only had the money for one ...
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Regards, Joerg
http://www.analogconsultants.com/
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Use another domain or send PM.
I1 V1 +8.4 | R1 = 240 | V2 .---------> 5 mA current source I2 | R2 = 570 | V3 .---------> 5 mA current source I3 | R3 = 100 | | GND
By solving for the current into V1, you will have enough information to solve for the voltage drops. The current into V1 can be found by using the substitution method for simultaneous equations.
#1 The voltage across R3 = Ir3*R3 #2 The voltage across R2 = (Ir3+I3)R2 #3 The voltage across R1 = (Ir3+I3+I2)R1
The sum of the resistor voltages = 8.4 volts therefore - #4 Ir3*R3 + (Ir3+I3)R2 + (Ir3+I3+I2)R1 = 8.4
And the total current into V1 is #5 I1 = Ir3+I2+I3
Simplifiy #7 #8 (I1-I2-I3)R3 + (I1-I2)R2 + (I1)R1 = 8.4v Carry out the multiplication indicated #9 (R3I1-R3I2-R3I3) + (R2I1-R2I2) + (R1I1) = 8.4v Move all I1's to the left and everything else to the right
#10 R3I1+R2I1+R1I1 = 8.4v +R3I2+R3I3 +R2I2 Factor out I1 #12 I1(R3+R2+R1) = 8.4+R3I2+R3I3+R2I2 Divide by (R3+R2+R1) #13 I1 = 8.4+R3I2+R3I3+R2I2 / R3+R2+R1 Seeing as I1 = I2 I can simplify this to #14 I1 = 8.4+.005(2R3+R2) / 910 I1 = 8.4 + 3.85 / 910
I1 = 0.0134615384615384615384615384615385
Now that the current into V1 is known, the voltages can be found The current through R3 is I1-10ma or 0.00346 and the voltage across R3 = V3 = .346 The current through R2 is I1-5ma or 0.00846 and the voltage across R2 is
You apparently missed my post, "Just Write It Down"...
Message-ID: ...Jim Thompson
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| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Cut the circuit below the upper 5 mA drain. The power supply and the top resistor with the drain form a new supply with an EMF of 8.4 V - 5 mA * 240 Ohms.
Perform the same operation with the lower drain. The EMF of step 1 will be dropped by 5 mA to 240 + 570 Ohms, and the internal resistance of the new supply is 240 + 570 Ohms.
Connect the bottom resistor to the supply of step 2 and solve your result.
The current drains have been marked as constant-current elements, so their infinite impedance does not enter the impedances.
I think you missed my meaning. It's not that theory must exist for the observation itself. It's that theory is primary to interpreting and understanding experimental results.
I've used the concept of a small-angle pendulum swing here, before. I added then the point about "observing"; that the period itself, when better timing becomes available to notice (itself, depending upon prior theory), is not well-enough predicted. That's an example of interpreting and understanding experimental results.
What remains (let's say, the idea that the diameter of the hole and the different diameter of the pin must be accounted in some way) is consistent -- at that moment -- with the idea of 'random.' The values may then be subjected to _other_ theory, the idea of Poisson events and its integral (Gaussian distribution) to see if the distribution has a skew to it for which some rule of thumb might then be applied, though otherwise ignorantly until better theory is developed. No one is prevented by what I wrote from accounting for an issue by making up rules that "seem to work until something better comes along." A bias, or skew, or some other element can certainly be found.
But take note, using _other_ theory to do so and inform that choice.
Your example takes place amidst a great deal of existing theory of one kind or another, as well. All of which helps to inform some rule of thumb, as well. Which makes the point well.
To strip away all of the veneer of cultural training, imagine a neanderthal posed along a mountain ridge, looking into the distance at a slightly curving horizon. Without any concept of "sphere" in mind. With that theory firmly held, _we_ are _able_ to "observe" that curve and adduce it to a spherical Earth 'theory.' We can "see" it. However, the neanderthal probably wouldn't have any way of even noticing the effect.
I might argue that theory not only informs observation, in many regards the lack of it prevents such observation from even taking place.
Now, let's add a "theory of a flat world surface" to this neanderthal's mind. Now, the neanderthal _can_ observe the curve, because it _differs_ from existing theory. And might even be able to formulate some rule of thumb about the deviation observed vs relative height on a mountain, perhaps.
But again, observation through theory.
Well, I hope the point I was making is clearer. Or not. ;)
I am lazy... I will spend hours finding the easiest way :-)
I drive my wife bonkers... she'll ask me to fix something, I'll study it for a week or two, then fix it... click... click... click... in 10 minutes... I keep her away from knives ;-)
But she's ultimately always happy... I can cut up a cabinet, change door placements, etc., and you'd never know it from the original. ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Ok, but: Lets say the guy with the pendulum never really had a chance to visit a school, very common in medieval days. But he wants to make clocks. Good clocks. So he might decide to conduct numerous long term experiments to see which pendulum works best without actually fully understanding why it does. IOW, not having a grasp on the theory does not preclude him from making clocks of superb quality and consequently a nice chunk of money.
Or he does notice, starts walking up to the curved horizon and the dang thang keeps moving away from him. Hence, the horizon must be afraid of him :-)
True.
Or he might decide "Ah, what the heck, let's get something to eat" :-)
There are two ways to arrive at good product. Theoretical and empirical, or a combination thereof. I've heard many old masters respond to questions "Well, that's just how it is" and these guys were real masters in their profession.
I grew up in medical ultrasound. Back in the 80's a lot of stuff around PZT-based transducers was not understood. Yet the front end parts and transducers of the old machines are not that much different in performance from the ones today, where we have oodles of computer horsepower to simulate and calculate just about anything. If we had said "Oh shoot, we don't understand the theory so let's not build but keep studying until we do" a lot of people in hospitals would have needlessly died.
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
Understood and point taken, as well. Life goes on. People could float on a board in the water before they had much more than a vague idea about it -- drawn from some collected observations.
...
This moves now into a protracted discussion, which I'd better not enter deeply here. But ad hoc rules, regardless of apparent value, are rarely any more than the vague appearance of a common "rule" from specific, repeated observation. Not a very good foundation, as ideas go, to build upon. As such things doesn't extrapolate very well to areas we haven't yet trod. (More on this in a moment.)
One can succeed with induction like this, almost as well with Tarot cards, as necromancy, as pretty much any idea that "seems to work" for some point in time and understanding. Some are okay as far as they go, of course. But it is very much like unearthing stones (fragments of utility) to make a farm wall. Each bit of this kind of inductive knowledge exists by itself and is barely connected to any other bit. Works great so long as you don't go outside the experience which created it.
Still, a farm wall is useful and may keep the cows in. No arguing with that. If you blow a hole in one part of it, the rest stays, too. That is it's power, in a way. A rock over on this part of the wall does NOT much depend upon a rock over 'there' for its strength. But at the same time, that's also its weakness. Structures formed like this cannot be efficiently used to carry extremely heavy loads, since almost none of it builds upon the strengths of other parts. They must be in close proximity to cooperate.
Science, of late, has focused upon deductive theory -- preferring to test and falsify based up deduction of general theory predicted into specific cases, given the particulars. It yields knowledge structures that are quite different. Induction still plays a role, but not nearly as important as before. In science knowledge, the parts are highly unified.
So in keeping with the above 'farm wall' concept, I'd now introduce the archway concept. Stones in science are shaped and fashioned so that they cooperate with each other, like stones in a grand, curving archway; with each piece lending strength to other pieces. The result is a structure that _can_ carry a heavy load. Of course, if you blow a huge hole in it, the whole thing falls down. ;)
Same nuggets of stone, two different structures resulting.
In fact, what separates science from other forms of knowledge isn't that science is "true" and the others less so. It's the unifying nature of the resulting body. It's no more "true" than anything else. But it is MUCH more unified.
I like to think of science knowledge as being "Borg." You can easily tell just how Borg some bit of knowledge is by how well connected it happens to be with "the collective." If it isn't connected into the collective, it's not Borg. And it's not science. Doesn't mean it is wrong. Doesn't mean it is useless. Just means it's not Borg/science.
Jon
P.S. There is a great book on knowledge; IMHO very easily grasped and extremely very well argued in six separate lectures. The author is Jacob Bronowski and the book is called, "The Origins of Knowledge and Imagination," 1979. Copies are available for very little money (only a few dollars) via abebooks or alibris. I consider it to be an excellent primer, enjoyably told, and I gladly recommend it to anyone. No matter how you come down on anything I write, I think you'll enjoy his lectures -- they were given to very young students and are very easy to follow, while simultaneously engaging, too.
What a pathetic story. But as always just your limited experience. I also worked for a company(Krautkraemer) in the 80s and those guys from the transducer department were called "the Phds" in the company. They knew what they were doing. The whole principle of operation was actually found/invented by 2 brother professors in the 40s who later founded the company, hardly any "Neandertals". ciao Ban
No such luck I'm afraid, Charlie. I did several semesters of college as a Comp Sci major, back in the late 90s, but I made a poor choice of school and things didn't work out. I was searching for somewhere to transfer to when I fell ill the first time. After recovering from that I had to give up my educational aspirations in favor of making a living, at least until I fell seriously ill the second time...Go on like that for a while and suddenly a decade has passed.
I do have a lot of "gen ed" prerequisite courses for transfer credit under my belt, I did them here and there at various community colleges (and Harvard's adult education program) over the years with the hope that someday I'd have the chance to enroll in a full degree program. Circumstances have granted me that opportunity now, and I feel this is probably my last chance.
then, your greatest problem might be just getting accepted into a program. Many EE programs are 'impacted', i.e. they have many more applicants than they have slots for students, so they become very selective. I know that twenty years ago, when I decided to go back and get an EE degree, I ended up moving out of state to get accepted to a program. Later, I found that I could get a masters in EE, even with my bachelors in psychology, and so was able to move back...
Just put on your application that you were tutored by Bill Ayers... you'll get admitted immediately... particularly if you apply to Berkeley ;-) ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
I say go for it. I don't think it's your last chance, but 30-ish is definitely a good time to return to school: You're still young enough you don't stick out like a sore thumb from the standpoint of getting job internships, going to recruiting events, etc.
One way around this is to sign up initially as a "non-degree seeking student" -- you're just paying tuition but not impacting the school's "quality," so usually anyone can get in as such. Then you go around and find a few sympathetic professors who'll let you sign up for their EE classes (usually non-degree seeking student require instruction permissoin to take any so-called "professional" level courses), do well in them, and then the next year petition for acceptance into the department... now with several professors on your side.
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