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Re: RF Antenna question
Shawn W. McClintock
开云体育Only
too glad to help. Yes, the PCB trace antenna is directional.. however, for short
distances of say under 300 ft. this is not very apparent. so if the cat is in
the house, you shouldnt have too many problems. if the transmiter output is 50
ohm, you can use a simple loop antenna that would fit inside the cat's collar.
all this would require is a 4:1 matching transformer because a loop antenna is
300 ohm, the matching transformer?is very easy to build or, if you want,
buy at many electronics stores. These are commonly known as CATV adaptors, for
older sets that have screw terminals for the flat twin lead type antenna cable
to be able to use the new coax based devices. Many TV shops have them and may
give you one for the asking, they can also be found at?Wal-Mart,
ect..?
?
Shawn
?
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Re: RF Antenna question
Mounir Shita
开云体育Actually, a PCB trace antenna sounds like a perfect fit
for my project. However, the circuit will be going on my cat. On the datasheet
it says that this type on an antenna is very directional. How true is that? And
is there a way around that problem.
?
Hope
the questions aren't to stupid. I'm very illiterate when it comes to
RF.
?
Mounir
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Re: Audio Line Level Potentiometer
Jim Purcell
Chris,
toggle quoted message
Show quoted text
My church wants to run a line level, balanced output from the back of the church to the front of the church (65')? Then, after running through a wall-mounted pot, on to an amp and then to monitor speakers.? The pot is so that the choir director will have volume control over the signal. |
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Re: Demonizing Hackers
Jim Purcell
Curtis,
It is really great to be part of this group. I'veYou mean I don't express myself well? :-) Or you we agree on the issue under siscussion? Jim |
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Re: PIC resources
Must agree, 18 is way better than 17. Hopefully soon they'll get all From what I have read about the dsPIC it sounds impressive. However at present time I think I will have little use for it at work. ?But I might play around with it at home some when it come out, just for fun. |
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Re: RF Antenna question
Shawn W. McClintock
开云体育Not at
all. Although the application this device was designed for?utilize a PCB
trace type antenna, it by no means limits you to such an item. There are of
course, several things you must remember with any antenna, PCB, wire or
otherwise.
1)
Ensure proper impedance from antenna to transmitter circuit. If need be, it may
be necessary to include some type?of? impedance matching
circuit.
2)
Maintain proper impedance through out your transmission
line.
3) The
actual antenna be a function of wavelength for the frequency you are operating
at.
?
You
can find out more about antenna design and building by exploring amateur radio
sites on the web. a search on most search engines for antenna design should get
you started.
?
Shawn
?
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Audio Line Level Potentiometer
Christopher Fetters
开云体育I
normally don't do a lot of electronics work but I do a lot of audio work.?
I can run a soldering gun... that's about the extent of my
expertise.
?
My
church wants to run a line level, balanced output from the back of the church to
the front of the church (65')? Then, after running through a wall-mounted
pot, on to an amp and then to monitor speakers.? The pot is so that the
choir director will have volume control over the signal.
?
How do
I spec the voltage/amperage on the pot? And how would I wire the pot inline with
a balanced signal?? Do you have any suggestions on companies who might
specialize in audio electronics parts?
?
The
board is a professional board operating at +4 dBU (not -10
dBU)
?
Thanks
in advance for the help!!!!
?
Chris
--------------------------------
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Re: PIC resources
How do you compare the PIC17 family to the PIC18 family? I only used PIC17 once before PIC18 was introduced. But on my current project I was comparing PIC17 and PIC18. I honestly couldn't find any reason why Microchip still made the PIC17 series. PIC18 is way better and about the same price.
Am I missing something ? Do you have good experience with PIC17? When we started this project I had intended to use separate PWM outputs to each of the three phases of the motor, therefore I needed three PWM outputs. The PIC17C756A was the best choice available with 3 PWM outputs. ?Later, changes were made to the motor and controller and I no longer needed separate PWM outputs. ?If I had known this earlier I would have used a PIC18 series chip. ? The PIC17 series was the next logical step for Microchip to take at the time they developed it. I believe it was just a step along the way to the PIC18. Microchip still supports this family, even though the PIC18 is a much better choice if you need more power than the PIC16 which is much cheaper, because of their policy of whenever possible always supporting past lines. They do this to prove to their potential customers that they will not be hung out to dry because of discontinued or obsoleted parts. |
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Re: PIC resources
In a message dated 10/29/01 1:47:26 PM Eastern Standard Time, mshita@... writes:
I have some years experience with PIC.Actually 5-6 years to be exact. I've built quite a few projects. My biggest was my senior project at college 3-4 years ago when I built a speech recognition system with a PIC16 and a PIC17. Worked okay, only got 70% recognition rate. Also built tons of small projects. Right now I'm playing with a robot I'm gonna squeeze a PIC18F to do some simple navigation. I did not know that Microchip had released any of the PIC18F series yet. ?All I have seen are listed as Future Products. |
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Re: The need to know!
G Ramasubramani
开云体育Jim,
?
?? It is tough responding to this mail
since you seem to have misunderstood nearly everything I wrote.
?
Rama
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Re: Demonizing Hackers
Curtis Sakima
Jim,
It is really great to be part of this group. I've long accepted the fact that I do not express myself in words very well....however....from what you have written, you and I seem to be (at least sorta) on the same page. Thanks for responding!! Curtis --- Jim Purcell <jpurcell@...> wrote: Curtis,I only would like to add that "a lot of times"after"all hackers get downgraded into criminals"If we look at specific acts and punish those I think ===== * * * We guarantee hits to your website * * * * * __________________________________________________ Do You Yahoo!? Make a great connection at Yahoo! Personals. |
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Re: PIC resources
I have been involved with PIC programming for several years. ?I have wrote code for several projects at work mostly dealing with motor and actuator controls, as well as, some test equipment. ?
My latest project is for a motor controller for NASA. The heart of the controller is a PIC17C756A. My controller drives a brushless DC motor and controls it's speed. ?My controller also monitors the motors speed, current, and temperature. This data is sent to a PC via a RS-232 interface. Commands for speed, as well as, current and temperature limits, can be sent to the controller from a PC via the RS-232 interface as well. Also these limits are stored on an EEPROM, which requires separate serial communications. The baud rates for the RS-232 communications are variable, based on separate signals sent to the controller. There is also a separate enable/disable for the motor. ?Current and temperature is monitored using the PICs A/D convertor. I have a web page, below is a link to my home page, from there you can get the link to my PIC programming page. |
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Re: Demonizing Hackers
Jim Purcell
Curtis,
I only would like to add that "a lot of times" afterIf we look at specific acts and punish those I think we will be better off. Labels are simplistic and often a convenience that bypasses thinking. They are sometimes a necessary short hand, but we should pay attention to what the label means and not equate reality with the label instead of what it represents. Laws which ... were ... intendedAs long as people think in terms of the labels instead of the acts that will continue. We should think, people who crack computers should be punished. Not hackers should be punished. It the long run it will be the acts that bring about court cases. To object to misuse of terms like hacker is probably foolish, I have tilted at windmills before. I am a language freak and it bothers me to see that many people have little grasp or effective use of same. Jim |
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Re: Demonizing Hackers
Curtis Sakima
Couldn't said it better myself.
I only would like to add that "a lot of times" after "all hackers get downgraded into criminals" (as Charles so beautifully puts it).... LAWS GET LEGISLATED Laws which (I know ) were probably originally intended only for the original bad-hacking /cracking act. But in the end, serve only to stifle creativity and make it hard for everyone else. Curtis --- Charles <hazenoff@...> wrote: I don't know how the group got diverted on to thetopic of hacking, other than my invitation to come and check out my yahoo group, hackerz_n_hickory... but anyways, to address your fears... Hackers, for the most part are really good at onething --------edited simply to reduce length---------- ... so don't demonize them..Just sorta like sayingall Christians are like Pat Robertson, or that all Muslims are like Osama Bin Laden..Generalizations suck... So, thank goodness for them <the hackers> ... and ifsomeone does something illegal, treat them like the crooks they are, I'm down with that.. what I'm not ok with, is everyone who likeselectronics/ computers/ etc, downgrading all hackers into the realm of criminals... ===== * * * We guarantee hits to your website * * * * * __________________________________________________ Do You Yahoo!? Make a great connection at Yahoo! Personals. |
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Re: capacitors and dielectrics
Jim Purcell
Doug,
The main reason I am on this list is because electronics hobbiestsDo you think so? I hope not. I used to think that radio Hams were too, but I think that while their ranks may be reduce (maybe they aren't actually) the ones who remain are just as dedicated. Maybe Electronics Hobbyists are like that too. Jim |
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Re: Capacitor - Charge- Energy
Jim Purcell
werrr,
i think because of the deformation of theThat idea works until you experience vacuum capacitors, no dielectric. So the storage medium seems to be the e.s. field itself. I think I missed that early on because a field is such a tenuous thing, at least in my mind it is. i think if there is vaccum between theIf that's so then the Collins radio transmitter spent big bucks on a device that does nothing. I was a broadcast tech for almost twenty years. Some transmitters had vacuum capacitors to avoid the problem of moist air causing arcing. I am moving to the conclusion that the charge is stored in this field, nothing new here and that the plates and dielectric support that field. If the capacitor is altered in any way it seems to me that the field will either collapse or change. But if it changes I don't buy the idea that the voltage could rise. That's just my intuition working. No support evidence. Now I'm going to wimp out on this discussion. I am losing interest, mostly because I haven't seen any new ideas proffered. I will continue to read but probably won't reply to the topic any longer. In my dotage I have a little less tolerance for perpetual rediscussion of some issues. I start of with a bang and eventually become disenchanted. Jim |
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RF Antenna question
Mounir Shita
开云体育Anyone
know about the MICRF102 Micrel part? It's a 300-470MHz transmitter chip. I don't
know anything about RF transmission and I'm just reading the ad on the current
issue of EDN magazine. It says here:
?
"The
MICRF102 QwikRadio transmitter is an easy to use, easy to manufacture
transmitter designed for use with a low cost PCB trace
antenna"
?
This
doesn't mean a I can only use a loop back trace on the circuit board to make the
antenna for the chip?
?
Mounir
? |
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Re: Cable TV signal amplification
Jim Purcell
Imran,
when i split the cable in two by A/B connector , one for my tv & other forMaybe, but we can't help without more information. Which signal are we talking about, the video, audio, RF. I'm assuming RF from the context. There are antenna splitters, that couple one antenna signal to two inputs. They can usually be had from any store that carries a variety of TV accessories. If the antenna consists of 'rabbit ears' however, the result will be less than ideal even with an amplifier. RF amplifiers are available in well stocked electronics stores. Jim |
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Re: Capacitor - Charge- Energy
i think if there is vaccum between theI don't think so. As long as their is an electric field between the plates, there is stored energy. With a dielectric between the plates, you can support a larger field, hence store more energy. Paul |
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