Don't remember exactly but they did razz me because I was wrong about the cigarette brand. It wasn't a Marlboro.
Did they at least notice that you were eating their lunch?
BTW, some day you should put up a small section on your web site about the history of your building, and most of all its construction. On the way home I kept thinking, how is that elevator holding position at a given floor without oozing water? Or does it just ooze a little and there's a runoff somewhere so it won't soak the foundation?
Huh? What's there to evaluate when one knows exactly what's going on? Putting in a CMOS amplifier wiped that problem away completely. No sense in evaluating a problem to death, I just moved on to the next problem. There was a whole punchlist and I had only two days.
Hey, that seems to not have been a fun birthday party if you are back so early :-)
I don't know. They sort of gave up without a fight. They had some firmware bugs they couldn't fix either; I think they lost the source code.
There's a big hydraulic cylinder/piston down in the the ground, with packing where the big shaft exits the cylinder. It does ooze a little, so the maintanance guys top off the water tank now and then. They add some soapy oily stuff, so the result looks sort of like milk.
The leakage just dumps into the elevator pit. I think it mostly just evaporates.
For anybody wondering, we're talking about a water-powered, roughly
80-year-old, hydraulic freight elevator.
We have to remember to park it on a lower floor. If we leave it at the top, especially over a weekend, it doesn't want to go down. So we have to get a bunch of people inside, jumping up and down, to break it free.
--
John Larkin, President
Highland Technology, Inc
jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
That's a bit scary since it goes in near the foundation walls. But I guess if it's been ok for 80 years it'll be ok for another 80.
What I found amazing is that the piston was still shiny as a mirror. Looks like new. Either good quality steel or the soapy stuff makes the water totally non-corrosive. But even then it's amazing because I bet the fortune cookie folks that owned the place before you guys must have had sitting it at the upper floors a lot, where the piston would be out.
Whoa, now that's scary. Some day everybody hops on the elevator with gusto to free it up and then it roars down super-fast because all the water had leaked out somehow ...
It is nice. Might benefit from some base resistors to keep the BFT25's from oscillating.
--
John Larkin, President Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
What do you say to running Monte Carlo analysis on the passives tolerance on your circuit? It would only be an overnight thing. I think you have more passive R sensitivity than you think.
satisfactorily. It is more compact than a diff amp or current source with= inductor, but there's no cost savings with DK's pricing. It is standard = current source level shift except it is voltage controlled by the 3.3V so= the shift tracks with power supply drift.
pendent.pdf
endent.pdf
rror.pdf
Your circuits are very nearly the same as Fred Bartoli's. Both would = have better performance with a ferrite bead in the collector of the final dc offset transistors collector. It would improve the ac impedance.
be cheaper to make that way. Shouldn't the pairs be monolithic at least?= That's all you really need.
Back in the bad old days of core memory there was a circuit called a current diverter, which was use to drive the fast pulses on the X an Y drive lines. Kind of a cross between a current mirror and a current mode DAC bit. Clean fast pulses, accurate to 5 % current. 2N2222 or 2N3904 would work fine.
For that (O.P.) poster here with the brachycephalic rectumitis (otherwise known as "with big head up butt" :-), I have added a 4th page showing power dissipation...
formatting link
...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 can do the sensitivity analysis manually. Gain error in the diffamp won't make much difference, since it will only change the gate drive a few per cent of 800 mV swing. My main error will be from resistance value differences causing the diffamp to have less than perfect common-mode rejection. That will map the Vcm voltage into the gate voltage. We'll use 1% quad resistor packs, which are matched to better than 1% in each pack. If I pick the sections right, the CMRR error will be below 2%, which is 40 millivolts. Add in miscellaneous stuff like opamp errors, and we'll still be well within my 100 mV error target.
I think the current-mirror circuits have the disadvantage that they are trying to measure a big quantity, Vcm, and subtract that out from the flop voltage to get gate voltage, and everything affects that subtraction. They have to do that to a couple of per cent accuracy, working through transistor beta and Early effect and Vbe and temperature issues, not to mention resistor tolerances. That's more difficult to do well, and to analyze. In my experience, all sorts of people make and sell things they call "2N3904" and a Spice model may not be very accurate. All the 2N3904's you plop into an LT Spice circuit default to being exactly identical.
Just how accurate *is* a 2-transistor current mirror made from discrete parts? How much might Vbe vary among a bunch of Mouser and Digikey 2N3904's at a given collector current? With my circuit, I don't need to know. Digikey alone offers them from five manufacturers.
--
John Larkin, President Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
is more compact than a diff amp or current source with inductor, but there's no cost savings with DK's pricing. It is standard current source level shift except it is voltage controlled by the 3.3V so the shift tracks with power supply drift.
Right. I use FBs in the collectors of current sources driving ramp caps. Remarkable improvements.
--
John Larkin, President Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
Not so with my method. Please do the math rather than hand-waving.
Doesn't matter. Do the math I recommended, and you ignored, analyzing the mirror once there's resistance in the emitter circuit.
Excuses, excuses, excuses. When you can't do math, you make obfuscations.
And your claim that I didn't model the PECL drive makes me think _you_ didn't do that LTspice schematic... one of your engineers did. ...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.
"Do the math" means determining the Spice params of all those various
2N3904's, and analyzing the consequences of building current mirrors that have generic 3904's that come out of a stock bin, purchased from various vendors. No, thanks. You do that and let us know what you find.
Consider how many params Spice has for a transistor. And how many it has for a resistor.
OK, you copied my slightly-inaccurate PECL model, and you came up with the same idea as Fred did. But I don't have to worry about the asymmetry of the open-emitter PECL drive because I'm not hanging an ancient 2N3904 collector on it. All I have is a resistor and the gaasfet gate, which is around 0.5 pF by my personal measurement. The less junk I hang on the gate node, with its 150 ps edge times, the happier I'll be.
Capacitive loading of the PECL things distorts the average DC levels, and messes up the DC shift accuracy, in any of the circuits. Your latest circuit runs the klunker at very low Vce, so collector capacitance is unnecessarily high.
Of course I designed that level shifter and Spiced it myself; it's done in my style. I'm designing the entire pulse generator myself, and I'll do the fast part of the PCB layout, but I'll let Paul write the ARM code for the USB control... he's awfully good at that. I'm a circuit designer and find hacking C to be annoying. All my guys have (too many) projects of their own. We just on Friday shipped the first four LVDT/synchro simulator modules to a big jet engine company (I did the architecture/manual/schematic, and arguably flubbed the DAC filters) but Rob and Karla and Paul did the FPGA and ARM code and the test/cal software, which was a lot more work than the PCB. Schematics are the easy part of a project these days.
I do have to force myself to let other people design things, their way, and make their own mistakes, or they won't learn. I can't hog all the architecture and schematic designs, as much as I want to.
I do appreciate all the hours you dedicate to designing stuff for my company for free, even though none of it has been usable so far.
--
John Larkin, President Highland Technology Inc
www.highlandtechnology.com jlarkin at highlandtechnology dot com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom timing and laser controllers
Photonics and fiberoptic TTL data links
VME analog, thermocouple, LVDT, synchro, tachometer
Multichannel arbitrary waveform generators
That's how I like to do it, and with things a *lot* bigger than an Opamp. I like to do processors and FPGAs the same way. That way I _can_ put the decoupling capacitors right on the pins they go on, without cluttering the schematic. Unfortunately, where I am now they usually insist on a physical representation of the chip (opamps and packages >>100 pins excepted).
No +Z?
Mine *strongly* for '-' above '+'. Feedback goes on *TOP*.
--
John Larkin, President
Highland Technology, Inc
jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
I really should pay you for the work you are doing for my company. Intern rates should be about right.
--
John Larkin, President
Highland Technology, Inc
jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
Yes, it is a TDC. I have different ones, too, but I cannot depart much from the existing engineering model. Replacing the architecture would be a lot of trouble.
BTW, you might find the 1993-10 issue of the HP-Journal interesting.
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