waashk/20ng huggingface dataset:
We have a setup with with 13 polaroid transducers and rangefinders. We would like to fire these three at a time with about 5 ms between firings. The three that are being fired do not fire in the same direction.   To further explain the situation, assume we are firing sonars A,B,C 5 ms apart each other. We should normally see an echo on A that corresponds to the distance. However, sonar A detects the INIT line of sonar B! The detection is actually through the transducer of sonar A; we can see a very faint 50Khz signal on the transducer, exactly at the time the init line of sonar B is activated.   We feel that there is some ground coupling that is causing this interference. We came to this conclusion since we are using a separate power supply for sonars B and C.   Has anyone else had any problems with these particular units and this type of experience? Your suggestions for remedies will be greatly appreciated.
jhawk@panix.com (John Hawkinson) writes: > My main question is the bulb: where can I get UV bulbs? Do they > need a lot of power? etc., etc.   he ones I have seen are all fluorescent tubes. Maybe you could find a small tube to go in one of those hand-held fluoro lanterns?  > One other thing: a friend of mine mentioned something about near-UV > light being cheaper to get at than actual UV light. Does anyone > know what he was referring to?  Blue lights. Ultra-violet (by definition?) goes from the blue end of the spectrum that people see to the radio spectrum (X-rays, cosmic rays etc).  possibly you could get light at the fringe of visibility (which people with false eye-lenses can see easily, since it's your lenses that soak up most of the UV), however since most people use UV to get other things to `glow', and the near-blue is less energetic, it would probably not work as well, if it worked at all. (lecture on basic atomic physics fits in here, about electron transitions (quantum leaps) and stuff.
If you're thinking of reactive polymers they're making ESD safe contauiners out of it. As far as being conductive goes anything with a resistance less than 10 to the fouthrth power ohms per cubic measure is classed as conductive per MIL-STD-1686 for ESD protection. My $0.02 ($0.016 US).
I need information on microstrip circuit design especially  filter design for the 1-3GHz range. Can you recommend any good books, journals, or microstrip circuit design software. . all help appreciated
I would be interested in hearing from anyone who knows of good software for antenna simulation, particularly in source form suitable for Unix workstations (though good PC software would also be of interest). I'm aware of the numerous mininec mutations, and have been using MN for some time now.  I'm primarily interested in HF, VHF, and low UHF (< 500 MHz) designs, mostly wire antennas, but for thick wires and mesh surfaces as well as for your basic thin wire assumption. Is anything interesting happening with NEC itself?  I've seen a version that was mutilated to run (sort of) under Microsoft Fortran, but I'm not sure how many "new and improved" versions of the code might be out there somewhere. I'd also be interested in non-NEC derivatives.  The ones I've seen have been aimed at microwave applications, but if there is something out there useful at the lower frequencies, I'd like to know about it. Thanks,
Hello--  I just bought a new portable CD player for the office, and I notice that it proudly proclaims "8 TIMES OVERSAMPLING" on the box.  Now while I think I understand what oversampling is (the rate of discrete "samples" exceeds the highest frequency component of interest by some factor), I don't understand this "8 TIMES" business...  It seems to me that when I bought my first CD player (was it REALLY 10 years ago?!), the specs said "4 TIMES" ...  Could someone please tell me whether I'm getting senile?  If I'm not, then what good does it do for the player to take samples at a higher rate?  If I really wanted better fidelity, wouldn't I have to have the same higher rate of sampling during the recording process?  Furthermore, am I wrong in interpreting the sampling rate (from the player's point of view) as being the same thing as the data rate for the bit stream coming off the optical medium?  Does this mean that the data rate (related to the rotational speed of the disk) has  changed since 1983?  I'm so confused...    --Cliff
Here is a different viewpoint.  > FYI:  The actual horizontal dot placement resoution of an HP > deskjet is 1/600th inch.  The electronics and dynamics of the ink > cartridge, however, limit you to generating dots at 300 per inch. > On almost any paper, the ink wicks more than 1/300th inch anyway. >  > The method of depositing and fusing toner of a laster printer > results in much less spread than ink drop technology.  In practice there is little difference in quality but more care is needed  with inkjet because smudges etc. can happen.  > It doesn't take much investigation to see that the mechanical and > electronic complement of a laser printer is more complex than > inexpensive ink jet printers.  Recall also that laser printers > offer a much higher throughput:  10 ppm for a laser versus about 1 > ppm for an ink jet printer.  A cheap laser printer does not manage that sort of throughput and on top of  that how long does the _first_ sheet take to print? Inkjets are faster than  you say and in both cases the computer often has trouble keeping up with the  printer. (I have a 486/33 and a lot of drivers cannot keep up with the  printer)  A sage said to me: "Do you want one copy or lots of copies?", "One",  "Inkjet".   > Something else to think about is the cost of consumables over the > life of the printer.  A 3000 page yield toner cartridge is about > $US 75-80 at discount while HP high capacity (~500-1000 page yield) > cartridges are about $US 22 at discount.  It could be that over the > life cycle of the printer that consumables for laser printers are > less than ink jet printers.  It is getting progressively closer > between the two technologies.  Laser printers are usually desinged > for higher duty cycles in pages per month and longer product > replacement cycles.  Paper cost is the same and both can use refills. Long term the laserprinter  will need some expensive replacement parts (consumables) and on top of that  are the amortisation costs which favour the lowest purchase cost printer.  HP inkjets understand PCL so in many cases a laserjet driver will work if the  software package has no inkjet driver.   There is one wild difference between the two printers: a laserprinter is a  page printer whilst an inkjet is a line printer. This means that a  laserprinter can rotate graphic images whilst an inkjet cannot. Few drivers  actually use this facility. (there is also the matter of downloadable fonts and so on)
My next project is to come up with an IF/detector module for fast -- 112 to 250 kB/sec -- packet radio use.  No fancy modulation scheme, just wide FSK for use at 902 or 1296 MHz.  I'm a bit familiar with the Motorola 3362 chip, but I wonder if there are newer designs that might work at higher input frequencies.  My goal is to come up with an inexpensive design for a receiver "back end" with IF input on one end and an FSK demondulator on the other.  I'm particularly interested in ways to use a higher IF than 10.7 -- do any current chips work up to, say 150MHz with internal downconversion so a normal IF filter can be used?  Any suggestions?  John
Greetings!                Situation:  I have a phone jack mounted on a wall.  I don't                     know the number of the line.  And I don't want                     to call up the operator to place a trace on it.
msf@skaro.as.arizona.edu (Michael Fulbright) writes:  > I am trying to build a synchronous demodulator and I've hit a snag. > In my application I want to be able to change the gain of an > op amp amplifier from 1 to -1, controlable via a digital input. > The most obvious way I've come up with is to use analog switches > to adjust the gain of the op amp. The only analog switch I have > experience with it the 4066. Unfortunately I want to switch an > AC signal which goes from about -5V to 5V, and the 4066 is only > for positive signals. >       I have recently used the 4066 to switch a bipolar signal.  I simply ran the 4066 off a bipolar supply, +/- 8V in this case.   As long as your analog input signal stays between the supply rails, the 4066 will work fine. Of course, your control (logic) input must use -8V as the logic LOW and +8V as the logic HIGH reference, so that either (1) all your driving logic must be 4000 CMOS with the same bipolar supply or (2) you must provide some kind of voltage level shifting circuit between the 4066 and the control logic.  In my case, I was able to use the bipolar supply all the way.
Gremilins have attacked my keyboard and the correction to my followup on audio relays got fouled up.   Varying lamp resistance, should read, "Varying lamp voltage" --  73, Tom ================================================================================ Tom Wagner, Audio Visual Technician.  Malaspina College Nanaimo British Columbia (604)753-3245, Loc 2230  Fax:755-8742  Callsign:VE7GDA Weapon:.45 Kentucky Rifle Snail mail to:  Site Q4, C2.   RR#4, Nanaimo, British Columbia, Canada, V9R 5X9
In article <afgE02Wb3dVu01@JUTS.ccc.amdahl.com>,  dws30@p1ps110cd.amdahl.com (David Sharpe) writes: > There are a few more details to radar and some > rumors that are not true.  A common one is that two beams are sent one > reading the car speed and one the ground speed.  If this were true then > calabration would be murder.  Hope this helps (Flame On)  Gee, then I guess the extra horn that's mounted in the floor of some SDPD cars, firing at the ground at a shallow angle, is just for show, huh?  (For calibration, they simply turn off one horn or the other.)
{Michael Fulbright} said    "Analog switches/Balanced"       to <All> on 04-15-93  01:08  MF> I am trying to build a synchronous demodulator and I've hit a snag.  MF> In my application I want to be able to change the gain of an  MF> op amp amplifier from 1 to -1, controlable via a digital input.  MF> The most obvious way I've come up with is to use analog switches  MF> to adjust the gain of the op amp. The only analog switch I have  MF> experience with it the 4066. Unfortunately I want to switch an  MF> AC signal which goes from about -5V to 5V, and the 4066 is only  MF> for positive signals.      How about using a 4053 it has a seperate ground for the     analog outputs.  It would get you 3 bits.   MF> Another part which caught my eye was the Analog Devices AD630. This  MF> is a balanced demodulator which appears to fill exactly the need I  MF> have. The data sheet was somewhat skimpy on application notes. Could  MF> someone comment on using this chip for the following application?      Or how about a multiplying D/A convertor?  This is     essentiallty what you are makeing.                   Stephen Cyberman@Toz.Buffalo.NY.US              Mangled on Fri  04-16-1993  at 13:36:11  ... Catch the Blue Wave!
Here's one I hope some knowledgeable readers will make a comment or contribution to:  In the State of Virginia radar detectors are illegal, period.  If you are caught with one it will be confiscated on the spot and will not be returned until after you appear in court and pay your fine.  The fine for having a radar detector accessible in a motor vehicle (even if it is not on) is $250.00.  Sorry, tourist, ignorance of the law is no excuse - they will get you too!  It used to be that the only way the law could be enforced was for an officer to actually see the radar detector.  Not any more!  Many law enforcement agencies are now using radar detector detectors.  Right, a super sensitive receiver that is capable of picking up RF from the radar detector itself.  My first reaction was "no way!"  But, guess again, these little buggers really work and the police are writing citations right and left for people using radar detectors.  One news story quoted an officer as saying that he had found the radar detector in all of the cars he stopped except one, and he could never figure out where it was - but he knew it was there.  This tends to make one assume there are few false arrest.  Now, before I get flamed, please understand that I do drive at or near the speed limit.  I do not need a radar detector to keep me from getting a speeding ticket.  But, I do like to know when my speed is being clocked or a speed trap is functioning.  My radar detector now stays locked in my trunk when I am in Virginia (which is what they want - and yes, what the law says, and I intend to obey the law!) and is only used in states where it is legal.  For my fellow hams, I am not a microwave person - my mind only works in the HF spectrum between 10 and 80 meters.  Microwave enlightment may be necessary.  So, the questions are -   What do the radar detector detectors actually detect?   Would additional shielding/grounding/bypassing shield stray RF generated by   a radar detector, or is the RF actually being emitted by the detector   antenna?   Are any brands "quieter" than others?
I just got an IBM-PC XT with no documents. Its a true IBM, and I was wondering if anyone had the definitions of the 2 8 position dip switches?
kludge@grissom.larc.nasa.gov (Scott Dorsey) writes:  >My car, unfortunately, has so much computer junk under the hood that it's >astonishingly sensitive to RFI.  If I key a 2W HT over the engine with >the hood open, the car loses timing due to the RF leaking into the  >distributor pickup.  Very poor design.  There was a news article a little while ago reporting a type of car (was it a Volvo?) was found to stall if you used a certain brand/model of cellular phone in it.  I seem to remember the car was recalled to fix the problem.
acollins@uclink.berkeley.edu (Andy Collins) writes:  >How thick do I need to make a PCB trace for 15 Amps of current? and >Does anybody have any other thoughts on the process (what kind of PCB >to use, materials, thickness of copper, any advice graciously accepted)?  In four replies, I've seen no hard numbers, so here goes:  For traces on the outside (not inner layers), expect, in 1 oz copper, at 15 amps, the following temperature rises versus width.  This is from Sams' "Reference Data for Engineers," seventh edition, Pg 5-30, which claims in turn to be from MIL-STD-275C...      width   Temp rise     inches  degrees C     ------  ---------      .125	100      .15	 75      .17	 60      .20	 45      .24	 30      .33	 20  At 10 amps, the rise for the .125 width is only about 30 degrees. Power goes as square of the current, plus the copper resistance goes up as temperature goes up...  Certainly .20" (~5mm) traces should be  ample for what you want to do.  And 2 ounce copper almost cuts the  required width in half.  (I'd do 2 oz at about 0.08" width myself,  I think...given that the _rated_ current is 10 amps and the 15 is a transient or fault condition.)
In article <C5sr8H.JpH@cbnewsl.cb.att.com> klink@cbnewsl.cb.att.com (steven.r.klinkner) writes: >Can anybody recommend a good, application-oriented beginner's reference >to RF circuits?   >Steve Klinkner                AT&T Bell Labs               srk@boeing.att.com  I have the ARRL Handbook for the Radio AMateur, and I'm getting the Solid STate Design for the Radio Amateur.
The pricing of parts reminds me of something a chemist once said to me:  "A gram of this dye costs a dollar. It comes out of a liter jar which also costs a dollar. And if you want a whole barrel of it, that also costs a dollar."  I.e., they charge you almost exclusively for packaging it and delivering it to you -- the chemical itself (in that particular case) was a byproduct that cost almost nothing intrinsically.
lihan@ccwf.cc.utexas.edu (Bruce G. Bostwick) writes: >Well, yes and no.  The _image_ can't be on the screen less than 1/30 >of a second, but a _mixture_ of images that's about 90% of the field >that was supposed to be there and 10% of the 'subliminal' addition >could be overlaid for one field, producing the same overall effect to >our sluggish retinae of a discrete image projected for 1/300 second.           This is a 1950s idea.  Supposedly, splicing in a frame of "Buy popcorn" upped popcorn sales in a movie theatre.  Big flap at the time. Congress involved.  Talk of making it illegal.  General agreement by networks not to do it.        A few years ago, some junior person at an advertising agency re-invented subliminal projection and one commercial went out on tape with single-frame messages.  It aired on a few stations, but a tech at one station, previewing the tape, noticed a flicker and looked at the tape frame-by-frame to find the "defect".  Big flap.  FCC notified. Commercial pulled.  Press reports. Embarassed ad agency.  You could probably find the press reports via Dialog or Nexis if you wanted.        Now that everybody has VCRs, it's not likely that anybody could get away with this on TV.
In article <93114.142835U19250@uicvm.uic.edu> <U19250@uicvm.uic.edu> writes: >Can anyone offer a suggestion on a problem I am having? >I have several boards whose sole purpose is to decode DTMF tones and send >the resultant in ASCII to a PC.  These boards run on the serial interface. >I need to run * of the boards somwehat simultaneously.  I need to be able to ho >ok them up to a PC>  The problem is, how do I hook up 8+ serial devices to one >PC inexpensivley, so that all can send data simulataneously (or close to it)? >Any help would be greatly appreciated!   Are the boards at all intelligent?  (I.e., run by microcontrollers?)  The easiest thing would be to have another line that says that one of the boards is talking to the PC.  When this line was true, the other boards could all hold off and not send their data.  This isn't a perfect solution, though, since you have to worry a little about making sure two boards don't decide to talk at the _exact same time_.  Other than that, I think you will need to hook up each board to "something" that speaks RS-232.  This actually isn't as hard (or as expensive!) as it used to be, though.  Assuming the boards talk relatively slowly (9600 BPS or slower), the PICs can coordinate things between themselves to multiplex the data.  (This is really just forbicly adding the suggestion in the first paragraph to your system.  And it assumes that each board doesn't talk more than 1/8th of the time, of for very long, since a PIC isn't going to be able to buffer more than, maybe 20-some bytes!)  You might want to check into the prices of multi-serial card for your PC, though.  I recently bought a Boca Research 2x4 card (2 parallel ports, 4 RS-232 ports) for a very reasonable $85.
Greetings. I received a reply stating that unless someone else 	confirms that the following company is operating, I should 	remove it from my lst:  >PCB Prototypes of Sandy, UT >Ronald Baker >8195 South 2660 East >Sandy, UT  84093 >Tel: [read below] 	 	This is from the COMM_PCB.FAQ (commercial PCB makers).  	Also, I don't have time to get the FAQ onto the sci.answers 	because of what I like to refer to is "red tape" - after the 	finals, I'll see what I can do... in the mean-time, anyone know 	of an FTP site that wouldn't mind a 250K file? :-)  	And last, I have some new entries for the SIMUSOFT list (mostly 	commercial/institutional stuff) but was wondering: should I keep 	the restrictions on the price of the software to be considered -> 	under $600 or should I include all those in 4 digit prices also?  	Take care.
In article <1993Mar25.161909.8110@wuecl.wustl.edu> dp@cec1.wustl.edu (David Prutchi) writes: >In article <C4CntG.Jv4@spk.hp.com> long@spk.hp.com (Jerry Long) writes: >>Fred W. Culpepper (fculpepp@norfolk.vak12ed.edu) wrote: >>[...] >>A couple of years ago I put together a Tesla circuit which >>was published in an electronics magazine and could have been >>the circuit which is referred to here. This one used a >>flyback transformer from a tv onto which you wound your own >>primary windings. It also used 2 power transistors in a TO 3 >[...] >10 years ago I built a 1'000,000 volt Tesla, and the thing was VERY >spectacular, but besides scaring/amazing friends (depending on their >knowledge of Science), and generating strong EMI, I never found anything >useful that could be done with it ...  Is there any real-world application >for Tesla coils today ? > >David Prutchi  First of all, realize that Tesla invented AC power generators, motors, transformers, conductors, etc. Technically, *ALL* transformers are Tesla coils.  In general though when someone refers to a Tesla coil, they mean an "air core resonant transformer". The TV flyback version Tesla coil (see the _Encyclopedia_of_Electronic_Circuits_ V3, 106-1 for diagram) has NOT an air core. It is of a class of circuit called "Oscillating Shuttle Circuit" (OSC). Generally OSC's are highly efficient, but this version uses transistors and resistors, which are very lossy devices. Typically Tesla used active reactances instead of passive resistors, so that he could achieve efficiencies of 99.5%, and better. The usual application of an air-core resonant transformer, or of an OSC, is to produce strong EMI for wireless broadcasts. How well do you think your computer screen would work if we removed the HF HV Tesla (flyback) coil from it? If we were to remove from our homes and industries all Tesla coils, our lights would go dark, our cars would sputter and die, our radios would go silent, our industries would grind to a halt, and we would have to go back to using coal for heat, gas for lamps, horses for transportation, steam for power, and telegraph for communication. Is that real world enough for you???????  GET THE MESSAGE! WE WOULD NOT HAVE 1/100 THE CONVIENIENCES WE HAVE TODAY IF NOT FOR TESLA. GIVE CREDIT WHERE CREDIT IS DUE!  If it had been up to Edison, we'd still be in the 19th century. (flame me at your own peril. I'm very good at putting edison down).  ----  ET   "Tesla was 100 years ahead of his time. Perhaps now his time comes".
> I really don't know where to post this question so I figured that > this board would be most appropriate.  try sci.energy