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Re: Teleportation
开云体育In a message dated 4/23/2004 4:07:56 PM Central Standard Time, dave_mucha@... writes:
Maybe we need an honest politician who is familiar with military ?
Whew!? All those phrases in the SAME little sentence?? A PIPE-dream, for sure!?? ("Honest Politician"???? Ain't no setch thang!) |
Re: Teleportation
开云体育In a message dated 4/23/2004 3:16:02 PM Central Standard Time, rtellason@... writes:
something goes wrong during that process,? you're screwed! ?
Mild verb, for this syntax,?methinks! |
Re: Teleportation
Curtis Sakima
A mark of a good moderator. Doesn't just tell supposed "off-topic" to
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"shut up". But leads to forum where the "off-topic" is "on-topic". Good Job! Curtis Dazzle Mom this coming Mother's Day season with flowers! ----- Original Message -----
From: Steve <alienrelics@...> Perhaps this should be on the Mad Scientist list. |
Re: signal oscillation
Keith
--- In Electronics_101@..., Stefan Trethan
<stefan_trethan@g...> wrote: thanthat is exactly what i meant. wanted effectswith the oscillations thanand see what happens in thereally great tool.The problems, as shown by a quick simulation, are fundamental to the opamp and the circuit configuration and do not require any details of the parasitics. That may be required later, but I believe a quick simulation is always worthwhile. It would have saved building a circuit that doesn't work. With regards to simulators, I would not recommend Pspice - it is overpriced. There are plenty of others, including usable demonstration versions, that cost from a small amount to nothing if you just want some basic functionality. Keith. |
Re: signal oscillation
Stefan Trethan
that is exactly what i meant. You need to be seriously skilled with it to take all that into account, which i am not. I say that it is definitely much harder to simulate unwanted effects than wanted effects because wanted effects use components you know of, because you designed and dimensioned them. the unwanted effects use parasitic effects too, which you definitely didn't design on purpose and don't know that much off. So to me it seems to be very much harder to simulate this problem with the oscillations than for example the wanted amplification of the amplifier. You say yourself you have the experience in this case from your work so you can properly use pspice for it. I would most likely just try to plug a capacitor on and see what happens in the hardware. Still i too strongly recommend getting that pspice because it is a really great tool. ST |
Re: Power supply design
开云体育In a message dated 4/23/2004 2:20:00 PM Central Standard Time, stefan_trethan@... writes:
electric toothbrushes requiring a 100Mhz processor to turn the motor NOT funny!? Have you dismantled one, lately?? Oh, maybe it was only several gates and a multivibrator, but there IS some "logic" in those, simply to control charging and on/off!? Yep!? (The Ni-Cads inside are often still good for "other stuff"; you'd think they'd [give out] first, but not always.? Besides, the EPA-Police will be all over you if you simply trash 'em.) |
Re: increase cable strength
Pablo E. Limon Garcia Viesca
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Hash: SHA1 You want longer wires? about 100 meteres? use a RS485 interface! lol!! if that is too much for you, then follow the previows postings ;) - -- Pablo E. Limon Garcia Viesca ID 279930 plimon@... al279930@... pelgv@... GPG-Key: 0x386906F1AD4C7FEA - -----BEGIN GEEK CODE BLOCK----- Version: 3.1 GO d? S+:- a-- C++++>$ UL++++ P+>+++++ L+++>+++++>$ E--- W++ N++ w--- PS PE Y+ PGP+++ t 5 X+ R- tv-- b+ D G e+ h* r++ !y - ------END GEEK CODE BLOCK------ www.geekcode.com -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.4 (GNU/Linux) Comment: Using GnuPG with Debian - iD8DBQFAiUiqOGkG8a1Mf+oRAmgFAJ4kpQSJDPss+4tDzZIBcfLl07vpyACgl50p KI0wYw4hblyYpjeNGjrNVyI= =yBIq -----END PGP SIGNATURE----- |
Re: signal oscillation
Keith
--- In Electronics_101@..., Stefan Trethan
<stefan_trethan@g...> wrote: On Fri, 23 Apr 2004 09:04:13 -0700 (PDT), k a <ktauyeung@y...> wrote:in myThe current source is from a PMT. What is a spicespice is a software for simulating electronic circuits. experiencehelp in designingI have to disagree that a Spice simulators are not good at such problems. Five minutes on one shows that the LT1028 will be unstable in a transimpedace configuration, and that is before the capacitance of the PMT is taken into account. Simulators are only as good as the models and the circuit used. If you don't include all your parasitics then they won't give the right answer. If the design is at a high frequency then the capacitance of each pad matters and so does the capacitance across a resistor. The phase margin of the LT1028 is not great for this sort of application, but then most opamps need some form of compensation in this application. Unfortunately, the design of such amplifiers is quite complex (and one area where I make my living). If you get a Spice simulator (I use Simetrix from Catena software - a quick search should find it, and a usable demo version) you could try different opamps to see if you can find a suitable one. For a 1 Meg feedback, around 0.2pF would stabilise it but that is not a practical capacitance. Other tricks have to be used to get round the problem. If you can live with a lower feedback resistance then the capacitor required to stabilise it will be a more sensible value eg at 100k, 1pF would do. This does reduce your signal to noise ratio and may require another gain stage to get the signal you are after. Keith. |
Re: Power supply design
Stefan Trethan
i disagree too / agree with keith.As for inductors / transformers on these application notes - DON'TI disagree. I often wind my own inductors because what I want usually Buying the demo board is no way of learning how to do it. it is a way of buying a ready-made unit, but then i can just go out and buy the supply module and that would maybe be even cheaper. Best approach if you have a scope and a generator. You can test it close to the frequency you will use it. If you use a small component tester you might want to make sure the measuring frequency isn't so far off that the result is worthless. of course you can calculate the error. ST |
Re: Breakaway headers
Stefan Trethan
On Fri, 23 Apr 2004 15:34:15 -0000, upand_at_them <upand_at_them@...> wrote:
They make header posts that you can break off what you need, but I this is one of the messages where i don't know what this answer is referring to. might be a good idea to add at least the one xentence containing the question. there are break off female header receptors. there are also ones that can be cut apart, but with these you loose the pin where you cut. the breackaway version has no lost pin, but i have only seen them single-row so far. if you need 2 row either use 2 parallel or use "cut apart" type. from my experience the breakaway type has slightly worse contacts (metal only on 2 sides). What i find hard to get hold of are female headers for attaching cables, the ones for flat cables which are self cutting are readily available but the type with individual contacts which you crimp on / solder is difficult to get. the contacts itself are not the problem but the plastic housing is hard to find. ST |
Re: signal oscillation
Stefan Trethan
On Fri, 23 Apr 2004 09:04:13 -0700 (PDT), k a <ktauyeung@...> wrote:
The current source is from a PMT. What is a spicespice is a software for simulating electronic circuits. it uses mathematical models for the parts. You can either draw the schematic or input a netlist. However, i would not suggest using it for the particular problem, as in my experience this is exactly where the simulation differs from reality. (may also be i am just not using the right models) You should get one version of spice for other things, it is a great help in designing circuits. You can experiment faster, at least with some circuits. ST |
Re: Power supply design
Keith
--- In Electronics_101@..., "Bruce Carter" <brucec@m...>
wrote: Probably. Give me a link to the data sheet and I will look it upI disagree. I often wind my own inductors because what I want usually doesn't exist. For power inductors I quite like the Micrometals E cores becuase they have high energy storage without having to mess about with gapping and are cheap. If you want gapped ferrites then MMG Neosid do a good range. To answer the issue of measuring the inductance, it is easy to do. I often use resonance - put a known capacitor across it, a series resistor and hook it up to a scope and signal generator. However, you shouldn't need to measure it. Design it, wind it, use it. I am not quite sure of what you want to get out of the regulator. If it is for car use and it runs off 12V, why regulate? Does the equipment you want to use require a very precise voltage? Keith. |
Re: signal oscillation
k a
The current source is from a PMT. What is a spice
simulator and what is it used for? The opamp I used is a LT1028, very low noise. Thanks. KT. --- Keith <keith@...> wrote: --- In Electronics_101@..., "ktauyeung" __________________________________ Do you Yahoo!? Yahoo! Photos: High-quality 4x6 digital prints for 25? |
Re: Teleportation
开云体育In a message dated 4/23/2004 12:49:54 AM Central Standard Time, phil1960us@... writes:
the use of serious and teleport in the same For sure!? As logical as "Military Intelligence"!!!!!!!!!!!!
? |
Re: Power supply design
Bruce Carter
Probably. Give me a link to the data sheet and I will look it up
for you. Transformers are usually for isolation, if you are willing to give up isolation you are probably all right. As for inductors / transformers on these application notes - DON'T try to do it yourself! The characteristics are usually so intertwined that the manufacturer recommends vendor and part number. Substitute and the circuit won't work. They usually sell evaluation boards with the necessary parts - a very annoying, but necessary investment for the hobbyist, because your chances of getting samples of the oddball inductors, special capacitors, schottky diodes, wierd transistors are almost zero - much less making a PC board layout without parasitics that will ruin your design. |
Re: Power supply design
Stefan Trethan
How can you measure the inductance? Incase I choose to make my own You can get meters, looking like digital multimeters, that can measure this. they are in about the same price range as digital multimeters. the professional version is a "resistance, inductance, capacitance measuring bridge" but a simple component meter is ok. You can even get multimeters with inductance measuring range. Another approach is with a scope and a ac signal. But you can buy ready-made inductors for which the value is known. What do you need the 12V for? You should be able to use 5V components, or use a regulator only limiting, no stepup, for motors (fans, maybe harddisk). If you take apart a old PC power supply you will find a inductor which carries one winding for 5V and one for 12V, maybe even one for 3,3V. you can use it , using the 5V winding for primary and the 12V winding for secondary. ST |
Re: Power supply design
Anthony Toft
I don't know about the LM2587 and would need more details of what youNo, no mains at all, it is for in car use only. need a transformer for safety/isolation. If you are converting from aYes, it will be in car, the data sheet says that for the input voltage I am looking at (10-15v) I have to use it in flyback mode, all the example circuits have a transformer in them. suitable for that configuration as I have never used it, but certainlyHow can you measure the inductance? Incase I choose to make my own tranformer? The problem is I will need 2 (for current requirements) and after the regulators the magnetics are the most expensive part of the circuit by half. -- Anthony Toft <toftat@...> |
Re: Power supply design
Keith
--- In Electronics_101@..., Anthony Toft <toftat@c...> wrote:
I am trying to desing a power supply, including a 12v flyback regulatorI don't know about the LM2587 and would need more details of what you are trying to do. If you are connecting to mains voltage then you need a transformer for safety/isolation. If you are converting from a car battery or something like that then you can just use an inductor - a transofrmer is not necessary. I do not know if the LM2587 is suitable for that configuration as I have never used it, but certainly other switching regulator chips are. Keith. |
Re: Teleportation
--- In Electronics_101@..., JanRwl@A... wrote:
In a message dated 4/22/2004 11:02:17 PM Central Standard Time,naw but I did find the use of serious and teleport in the same sentence some what oxymoronic... |
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