Limiting that comparison to the range of sizes that C0G is available in (films get bigger), it's probably true enough. And yeah, cost besides.
Not to mention ESL of an MLCC versus leaded film (chip films aren't all that common, though PPS is pretty good too, I understand).
And yeah, if you want to get into big capacity, I know where you can get water cooled films well over 10uF with DF < 0.1% sort of range. And they're not cheap either. :)
JUST like that. The government can't do anything well. Some things it must do and it doesn't matter if there's waste. It's gotta be done. Those are damned few, though.
It's hard to know what the real object here is... being a Larkineque bloviation with no exact specification/definition... only the usual vagaries.
However, if the object is to get an accurate 60V P-P sine wave at
107kHz with good side-bands, the solution is trivial and _does-not_require_ precision tuning, nor high Q.
Any kiddy just out of school knows how >:-}
I'll post the trivial solution when the bloviating asshole stops spouting.
(Simulation results posted to ABSE)
("Asshole" IS a transitive verb... asserted for those of you considering criticizing my use of "pluperfect" :-) ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 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.
High Q does reduce the power required, though--power dissipation per radian of phase is E0/Q, where E0 is the instantaneous energy stored in the tank. Any of us can hook up some big ugly power op amp, but John's tank has a stored energy E0 = 1/2*75uH * 0.5A**2 = 9 uJ, so the drive power is
P_drive = (2 pi f/Q) E0 = 6.3W / Q.
Q=50 is dramatically easier to drive than Q=2, no?
And high Q also improves the THD, unless (as in the Y5V varactor proposal) the distortion comes mostly from the reactive components.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058
hobbs at electrooptical dot net
http://electrooptical.net
How do your comments add to the information content? Sounds like mostly sickophant support.
I said high Q was not required. The exhibition was Q~1. It's be nice if we could return to real engineering on this group instead a BS after BS.
As long as Larkin wants to name-call I will simply bring him down technologically. He really is quite incompetent. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 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.
My LC simulates a transducer of some sort, possibly an LVDT sort of thing; I'm not allowed to know, exactly. The point is that I do need to simulate the transducer impedance and its waveform, distortion and all, when driven by the given circuit. My Q will be close to the actual device's Q. And I'm required to hit the drive resonant frequency pretty close.
--
John Larkin Highland Technology, Inc
jlarkin at highlandtechnology dot com
http://www.highlandtechnology.com
Precision electronic instrumentation
Picosecond-resolution Digital Delay and Pulse generators
Custom laser drivers and controllers
Photonics and fiberoptic TTL data links
VME thermocouple, LVDT, synchro acquisition and simulation
Bloviate! Bloviate! What a dork ;-) ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 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.
Didn't try that. But we found the problem on a production board that had been reflow soldered. The caps on the reel, in stock, were similarly low in value.
--
John Larkin 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
I have measured many C0G (aka NP0) chip capacitors that lost 40 % C or more at rated voltage, but still have very low tempco. That includes several batches each from multiple manufacturers. Alright that was 30 years ago, but still. Not better than films for bias voltage, only for temperature.
y a mosfet and have about 60 volts p-p across it. L is about 75 uH, so Xl i s around 50 ohms. Peak inductor current is half an amp or so.
ielded inductors are mostly +-20%. So, how to tune it?
d P26x16 gapped pot cores with a central hole.
e fine.
number is 2098922 - you can also get it out of Newark if nobody else in the US stocks it.
bably more than enough to take the +/-3% tolerance on the heavily gapped co re pairs.
ou may want to find a coil winding shop to make your coils. Hand coil windi ng machines are pretty cheap, and if you only need 20 parts it wouldn't be too much of a chore to do it in house. Most places where I've worked have h ad a coil winding machine somewhere around the place, but the Nijmegen Univ ersity workshop threw their's out a few years ago because none of the new h ires could imagine winding a transformer.
all that easy to get hold of, but I managed it - you should find it easier.
re.
ded slug).
oviation with no exact specification/definition... only the usual vagaries.
z with good side-bands, the solution is trivial and _does-not_require_ prec ision tuning, nor high Q.
In fact John Larkin has spelled out that it is to substitute for LVDT coil (or something like it) in a test bed for one of his customers.
an of phase is E0/Q, where E0 is the instantaneous energy stored in the tan k. Any of us can hook up some big ugly power op amp, but John's tank has a stored energy E0 = 1/2*75uH * 0.5A**2 = 9 uJ, so the drive power is
l) the distortion comes mostly from the reactive components.
He seems to be planning on driving it in class-C, so the energy going in is almost a Dirac spike, with equal levels of every harmonic up to the width of the spike.
Obviously the spike gets smaller if the Q of the tank is higher. With Litz wire he might get a Q of about 150.
Baxandall's class-D driver feeds in what is nominally a square wave, where the harmonics decrease in proportion to the harmonic number, but the feed i nductor inject a load-independent second harmonic component, which means t hat there's a constant harmonic content for sufficiently low loads.
My current mirror variation of that can push the harmonic content down by 3
0 or 40dB, to a level where the non-linearity of the ferrite introduces as much harmonic contentas the drive.
I've modelled that in LTSpice using the John Chan model - we got a third ha rmonic content about 80dB below the funadamental with a tolerably heavily g apped core, and confirmed it on a test winding (hand wound and shipped off to London for measurement on a friend's rig). The design then moved to the core with the biggest gap that I could buy, where the harmonic content simu lated at 104dB down.
That needed a better drive, which I've designed, bought the parts for, and should eventually build.
You've just lost your temper, is all. You claimed that Q didn't matter, and I showed that it reduced the drive power by a lot, from watts to tens of milliwatts. You like math, remember?
Of course high Q isn't required, if you're driving it with a Kepco BOP, but (at Q=1) six watts of gate drive is a bit ridiculous. You could roast hot dogs on the driver stage.
Today's feature is like Godzilla vs Rodan. Both quite capable of ravaging Tokyo as long as the other one isn't around. ;)
Pass the popcorn, Mabel.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058
hobbs at electrooptical dot net
http://electrooptical.net
I sort of doubt that. John's customers are usually a bit higher tech than that. It could be an inductive transducer that has some built-in capacitance, e.g. a resonant magnetostrictive drive or something driving air or a fluid. Matching acoustic impedances is a lot easier with a resonant transducer.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics
160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058
hobbs at electrooptical dot net
http://electrooptical.net
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.