waashk/20ng huggingface dataset:
Does anyone know what frequencies the wireless transmitter/receiver microphone systems that Radio Shack sells operate at?  I've tried everything short of opening one up (not actually owning one makes this difficult...) and just looking..  Any help would be greatly appreciated..  These systems are designed for wireless PA systems, etc..     					Thanks,
In article <1993Apr22.060607.12380@macc.wisc.edu> jvannes@vms.macc.wisc.edu writes:     I would also be interested in the application here.  I work with a Dance and    Technology program, and want to build something to track dancers on a 30 foot    wide stage from 50 feet away.   Could make for some interesting choreography... light and sound could be  controlled directly by the position of a dancer on stage, or by the number of dancers on stage. Neat.  You could even build a spotlight that follows the dancer around on stage!  Can you tell us more about what you're doing? Sounds like a very cool program.
In article: <1qlg9o$d7q@sequoia.ccsd.uts.EDU.AU> 	swalker@uts.EDU.AU (-s87271077-s.walker-man-50-) wrote: >I really don't know where to post this question so I figured that >this board would be most appropriate. >I was wondering about those massive concrete cylinders that >are ever present at nuclear poer sites. They look like cylinders >that have been pinched in the middle. Does anybody know what the >actual purpose of those things are?. I hear that they're called >'Cooling Towers' but what the heck do they cool?  Except for their size, the cooling towers on nuclear power plants are vertually identical in construction and operation to cooling towers designed and built in the 1890's (a hundred years ago) for coal fired power plants used for lighting and early electric railways.  Basicly, the cylindrical tower supports a rapid air draft when its air is heated by hot water and/or steam circulating thru a network of pipes that fill about the lower 1/3 of the tower. To assist cooling and the draft, water misters are added that spray cold water over the hot pipes. The cold water evaporates, removing the heat faster than just air flow from the draft would and the resulting water vapor is rapidly carried away by the draft. This produces the clouds frequently seen rising out of these towers.  That slight pinch (maybe 2/3 of the way up the tower) is there because it produces a very significant increase in the strength and rate of the air draft produced, compared to a straight cylinder shape.  The towers are used to recondense the steam in the sealed steam system of the power plant so that it can be recirculated back to the boiler and used again. The wider the temperature difference across the turbines used in the power plant the more effecient they are and by recondensing the steam in the cooling towers before sending it back to the boilers you maintain a very wide temperature difference (sometimes as high as 1000 degrees or more from first stage "hot" turbine to final stage "cold" turbine).                                          R. Tim Coslet
> Also are they really commonly avaliable in the states, and if so, then > how much are they and who sells them (maybe if I cant get one here, I'll > write to one of the companies over seas..)  ----------
In article <1993Apr23.205906.10745@sol.ctr.columbia.edu> seema@madvlsi.columbia.edu (Seema Varma) writes: >Hi, >	I am looking for a high speed  >D-to-A converter ( at least 8 bits >and 150MHz) for testing a chip - any >ideas on where I can find such a monster? >A paper in the January issue of IEEE Journal >of Solid-State Circuits (authors from Philips >Eindhoven) mentions a 1GHz, 8bits, GaAs DAC >they use in their testing, so I know that  >such circuits are around somewhere.     TriQuint (Beaverton, Oregon), has been selling an 8 bit, 1 GHz D to A for several years.  I have used it and it works well, faster settling time and smaller glitch area than any video d DACs I have seen.  Also, they have been developing a more precise version that may be for sale now - it's somewhere in the 10 to 12 bit area at 1 GHz.
> Though, 1500 real watts still isn't impossible.  About 125-150A with > a 12V alternator, less if the alternator produces higher voltages.  Anyone claiming that 1500 "real watts" isn't possible in a mobile should dig through their back issues of 73 (and, I think, QST) for a description of the mobile installation of that most revered of OMs, W6AM.  As I recall, this included a Heath 1kW (DC in) amp (what was that model number...SB- something....  my mind is turning to the usual Friday mush...) and was run  full-out CW fairly regulary.  The car's electrical system had been modified,  including a rather seriously-heavy-duty alternator, but such an installation  HAS been done, and so IS possible.  This installation was the source of the legendary story of W6AM sitting in the car, and paging his wife over the department store PA systems!
I remember, back before commercial mikes with the "PZM" label (for Pressure Zone Microphone) started showing up, I read an article, in some engineering journal, that described the principles involved. All the physics aside, from a practicle standpoint the author's said they built a prototype with nothing more than a small Sony lavelier mike laid up against a large aluminum disk.  In demonstrating it at a presentation to audio engineers, this was impressive enough that the people present were bugging them about where they could buy them.  Anyway...I want to build some to use as "choir mikes" (wide coverage). I've had good luck using some small electret mike elements I got from Digi-Key - most of these are limited-bandwidth, peakey units but for a buck or two more I got the ones spec'd to go out to 20kHz with a bit flatter response.    The distance of the mike opening from the flat plate is kind of critical.  I'm debating whether to mount it on it's side, which puts the opening a shade under 2mm from the plate, or mounting it with the opening actually pointing down into the plate at a small clearance.  I haven't dissected a unit like you can buy at Radio Shack to see how they do it.  Thoughts?
Any info on modern 20MHZ or better dual trace scopes would be appreciated. Should I buy a used one or a new one?  And where?  Please E-Mail.  Thanks in advance.  Ken
** For my computer law module I have been asked to write a computer     contract for the supply of computer software to a business. The    software is being especially written for the company.     Would anyone, per chance happen to have a copy of a computer    contract on their system which they could mail me.     If anyone has a computer contract but it contains sensitive     material then I can assure them that it will remain confidential    and I will not pass it on, or allow anyone else to view it.     Thanks.
Much deleted about assembly in USA vs. other,  I wish to focus on the subject of warm-running amplifiers:  > : >  Sure the amp runs very fairly > : >  hot - but that's how you get an amp to sound incredibly good. >  > : An amp that runs hot has no bearing on how it's gonna sound. > : The amp you have probably is running Class-A the whole day. >  > : because either the engineer or manufacturer of that amp wanted > : to skimp on heatsinking or cooling to save costs!  Hmmmmm.... >   There is a correclation between warm-running amps and good sound, or in your words, "it DOES have a bearing on....".  Now, I don't suggest that everyone run out and create combination stove/amplifiers that will degrade lifespan, but a cold-running circuit is much more suceptible to temperature variation with varrying current than is a warm-running one.  And since junction resistance is a function of temperature, this has a detrimental effect on linearity.    a few facts: -bias points vary with temperature -junction resist varrie with temp -Adcom products do NOT run class-A  If you still don't beleive this assertion, consider the warm-up requirements for most good test equipment, or better yet, just listen to an amplifier warm-up.  On many designs its quite audible, on mine, about 20 minutes for the output stage, many hours for the drivers.  Fortunately the drivers are not switched.  In any experiment, or when drawing conclusions from listening, betcareful to seperate the effect of device temperature from bias (idle current) level.  Both have a positive correlation with low distortion and "good" sound quality, and high bias results in warmer operation, all other factors being equal.
One not-so-quick question to throw out there for you guys...  For our class project, we need to design and build a power supply to the following specs:  Voltatge:  adjustable from 1-12V Current:   *limited* at 1A  Voltage must stay within 2% of designated value for I from 0-1A AC ripple less than 5 mV (rms)  Of course, we can't just use an adjustable voltage, current-limiting regulator chip ;^)  Our problem is with the current limiting (i.e. we've found stuff to do the rest of the parts of the circuit).  What the supply must do, if presented with a load which would draw more than 1A, given the supply voltage, is reduce the voltage so that the current will equal one amp.  Thus, if we were to short the thing with the ammeter, we should read one amp.  If we measure the current through a 1 ohm  resistor at 12V, we should read one amp (and the output voltage, by necessity, must be 1V.  The only basic idea we have seen for the current limiter involves a circuit which will pull current off of the base of the output  power transistor, and therefore reduce the output.  So, does anybody have any ideas we could work from?  Thanks in advance.  Andy Collins, KC6YEY acollins@uclink.berkeley.edu
In article <1993Apr22.220549.26828@dmu.ac.uk>, cph@dmu.ac.uk (Chris Hand) writes: |> Carter Ames (camter28@astro.ocis.temple.edu) wrote: |> :   Why does a lead acid battery discharge and become dead (totally unuseable) |> : when stored on a concrete floor?    I think it's because the lead gets coated with lead oxide if the battery is not being charged or discharged. I remember some advice from an ancient car manual guide my father had, which was to use car batteries to power a garage clock or something similar when they're not in a car. This is supposed to  prevent the oxidation but I've no idea if it really works. The concrete floor connection is a red herring.  |>  |> It could be that you stored it somewhere that it could become covered |> by moisture or damp air, which would short out the terminals.  This may contribute to discharging but would be reversible.   |>  |> The same thing happens to my car (Citroen 2CV) -- damp gets under the |> bonnet (US: "hood") and shorts the spark-plugs to earth so it won't start. |>  |> The solution (for the car) is to clean the plug leads and spray with |> WD-40 (moisture repellant).  If damp *is* the problem, then storing the   Well, this is off-topic, but back in the days when I used to drive bangers I never found WD-40 to do anything that wiping with a dry cloth did'nt do. I think the effectiveness of WD-40 is a myth invented by the guy who owns the company.  |> battery off the ground may help.  I'm not sure if spraying with WD-40 |> would be safe since it is very flammable (high percentage petroleum). |>  |> Just a thought... |>  |> Chris |>  |> --
klp@doe.carleton.ca (Ka Lun Pang) writes:  >  > Hi folks, >  > I borrowed a VHS tape from a friend and it has a warning in the begining sayi > that attempts to copy the tape will result in destroying the copy and the > original. I found this unbelievable as playing and recording are two differen > processes. However, I've never seen this tape being sold anywhere so I don't  > want to take the chance even it's small. >  > Anyone has experience in this kind of self-destructing video tapes? >  > Thanks in advance. >  > -- > Ka Lun  Pang (a.k.a. Andy) - Lost between frequency and time on the unit circ >                       email: klp@doe.carleton.ca  >                                DoD# 0687   To put it bluntly, they are full of it.  Paying a tape is playing a tape.  There is no difference whether the  output goes to a second VCR or to a TV.  (How the VCR or TV reacts to  this signal is a different story - see messages pertaining to macrovision  copy protection.)  In order for the tape to self-destruct, it would have to have circuitry  of its own within the tape case.  The circuit would have to somehow  magically determine what the output of the VCR is connected to.  The  circuit would then have to have an erasing head to actually do anything.  It is a pretty lame scare tactic.  (I've seen something similar on a BBS. When the SYSOP wanted to, he could have a message sent to the user's end  saying that it is sending the code to format your HD.)
Dear Netters I want to send EMG-signals from a running person to a computer.  Each signal is 4KHz wide and there is up to 30 of them on each running person. The signal is only to be sent over a few hundred  meters. It seems to me that the frequency intended for this use is about 150MHz and about 440MHz. To make the transmitters as light as possible I suppose it will be best  the to send the signals in an analog form. As this application is rather  specialized I do not expect to be able to buy the exact transmitter- units i need. On the other hand I imagine that I can buy the receiver somewhere. I  need a multichannel (up to 30 channels) receiver or 30 complete   receivers in some rack system where one can add as many receivers  as needed in the particular case. DO ANYBODY KNOW IF THERE IS EXISTING SUCH RECEIVER  SYSTEM ON THE MARKET?
In article <1993Apr21.170932.18356@news.columbia.edu> kn1@cunixa.cc.columbia.edu (Kimball Ng) writes: >kolstad@cae.wisc.edu (Joel Kolstad) writes: > >>One other thing... there are bubblejets, and then there are BubbleJets. >>There are a few bubblejets out there that produce rather mediocre output >>(such as HP's dinky little BubbleJet), whereas most produce really good >>looking output (such as HP's DeskJets).  IBM and Canon both produce some of >>the really good style bubblejets.   ** I am considering either an inkjet or bubble jet printer. I've seen    inkjet printers and I was impressed with the near lazer quality.     I have heard a lot of bad things about the cheaper bubble-jet printers.    Does the ink smudge very easily and take a long time to dry ?     Thanks.
I was just wondering one thing, actually two. ( I hope that this is the proper place to post this subject)    Why does a lead acid battery discharge and become dead (totally unuseable) when stored on a concrete floor?     I decided to bring the battery in from the lawn mower and the motorcycle from the unheated garage this year, *to preserve them* and I just went to use them and noticed that not only do they not work, but  they act like the two terminals are shorted.  I asked a friend and he said that you should never do that, 'cause it ruins them, but he couldn't tell me why.
In article <3402@tau-ceti.isc-br.com>, jimc@tau-ceti.isc-br.com (Jim Cathey) wrote: >  > In article <alan-210493163447@17.129.12.26> alan@apple.com (Alan Mimms) writes: > >Actually detecting a BREAK is done by watching for a "character" containing > >all zero bits with the framing error resulting from its receipt.  This >  > True enough, but... >  > >means that the line stayed in the zero bit state even past the stop bit > >time slot, which basically indicates a BREAK.  There is no special way to > >detect BREAK that I have found other than this -- there's no magic signal > >generated by UARTs, etc. >  > Zilog SCC: > --------- > 	RR0[7]:  Break Detect >  > This is a very popular part, but it has a number of quirks, especially > in HDLC mode. >  > Signetics 68562 DUSCC: > --------------------- > 	RSR[2]:  Break Start Detect > 	RSR[3]:  Break End Detect >  > Two of the bits in the Receiver Status Register.  You can enable an interrupt > on either of these bits going high, too.  Also, only one NULL will be put > in the FIFO per break detected. >  > This is simply the best serial chip I've ever worked with.  _Many_ less > quirks than the SCC, which is IMHO second-best.  (Death to 8250 devices!) >   And I thought I knew a lot about serial devices.  Perhaps I should just keep my big mouth shut.  Sorry.
zjoc01@hou.amoco.com (Jack O. Coats) writes:  >The same folks now have out LBL (Little Big Lan) for $75.  I think you >get it for $50 if you already own $25 Network.  LBL works with Arcnet, >parallel ports, and serial ports in any combination for up to 250 or so >nodes.      LBL now offers ethernet support also, although presently it is limited to NE1000/NE2000 style boards.  LBL owners can get an update for $8.50.
A little correction on my previous post about an hour ago. Please replace the term 'EEPROM' with the term 'EPROM' wherever it appears. (Don't not why I added that extra 'E' every time.)
In article <1993Apr23.191808.10835@rwwa.COM>, witr@rwwa.COM (Robert Withrow) writes: > In article <1qf44aINNll@rave.larc.nasa.gov>, watson@nimbus.larc.nasa.gov (Catherine Watson) writes: >  > | I gave up after a year of > | letters and phone calls.  I got the impression the FCC was powerless and it  > | was up to the cable company to correct the situation. >  > Isn't there some *formal* action a citizen can take that *requires* the > FCC to, at least, generate some paperwork? >  > --  >  Robert Withrow, Tel: +1 617 598 4480, Fax: +1 617 598 4430, Net: witr@rwwa.COM >  R.W. Withrow Associates, 21 Railroad Ave, Swampscott MA 01907-1821 USA  For those who are interested, the FCC does indeed care about cable leakage, particularly into the aviation nav band, or leakage that is "causing interference to other services".  Part 76.611 details specific limits to acceptable leakage, and measurement technique.  If you will clearly document your problem, and measurement technique (a signal level meter with dipole is the normal approach, remember to correct between measurement data and microvolts per meter) and fax or mail the details to Mr. John Wong Cable Branch, FCC 1919 M st. NW Wash DC, and a copy of your letter to the local cable company, you will get results.  In fact the cable company will probably start treating you much better when they realize you have figured out how to get the FCCs attention.  What is important is to document your case as it relates to the applicable rules.  However the cable company *is required* to at least check out every complaint of leakage.  They must file with the commission and maintain on premises a yearly measurement report that details the results of leakage testing.  But remember, call the cable company first, and give them a chance to work to correct the problem before contacting the commission.  I am in the business of measuring cable system leakage via the airborne method.
In article <1993Apr26.210417.2984@socrates.umd.edu>, johng@socrates.umd.edu (John Gustafson) writes: > ruck@beach.cis.ufl.edu (John Ruckstuhl) writes: >  >>I know this is a long shot, but does anyone know what solvent I should  >>use to clean duct-tape adhesive from carpet? >  > May I tease out a sub-thread from this discussion? >  > Can you all please tell me how to remove  the stickers from new houses' > appliances and outdoor lampposts?  Especially the lamppost, right on > the glass.  Isn't there something you can rub into stuck-on labels that > will release them from their death-grip on glass or other hard surfaces? >  > Many thanks for any help.   >  >                                               John >  > John Gustafson   johng@socrates.umd.edu >
I've got two lines coming into my apartment. Two different telephone numbers. When I ordered the second line installed, instead of bringing out another 4 wire bundle, the telco just connected up to my yellow and black wires. So I have one line on red & green and the other on yellow & black.  Today I was monitoring the voltage on both lines. I had a voltmeter across the red and green and read back 52 volts. I then lifted up the receiver on my second line.(black & yellow wires) The voltage dropped to 31 volts on the first line. (red & green wires) I repeated this experiment with the second line(monitoring black & yellow and lifting the handset off the cradle on the red and green line.) It also dropped to 31 volts.   Why is this ? I thought these were separate lines.  Next I went to the 66 block and disconnected the blue and white lines coming in from the telco cable. I then disconnected all the phones in my apartment and went back to the 66 block and did some resistance measurements. Both lines read open.  I'll appreciate any help on this. Is this considered normal ?  Guy Urbina
In article <1ptolq$p7e@werple.apana.org.au> petert@zikzak.apana.org.au (Peter T.) writes:  >Since an on-hook line is aprox 48-50V, and off-hook it usually drops below 10V. >How about an LED in series with a zener say around 30V. >On-hook = LED on >Off-hook = LED off. >Would this work? If anyone tries/tried it, please let me know.  Not recommended. Your circuit would take too much current, when telephone is on-hook. Telephone company does not like it.
In article <C5uLqG.I5@acsu.buffalo.edu> v064mb9k@ubvmsb.cc.buffalo.edu (NEIL B. GANDLER) writes: > >	How does the radio Electronics free information cards work. >Do they just send you some general information about the companies that >advertise in their magazine or does it also give you sign you up for a >catalog.   Radio-Electronics sends each company a bunch of computer-printed address labels for all the people who circled that company's number.  The company sends whatever it wants to -- normally a catalog.
In article <20756.2bd16dea@ecs.umass.edu> alee@ecs.umass.edu writes: > >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. > >        Question:   Is there a certain device out there that I can >                    use to find out the number to the line? >        Thanks for any response. >                                                    Al > >     How about calling someone with the Caller ID service and have them call you back with the number?  --
ab616@Freenet.carleton.ca (Marc Dion) writes:   >For a project of my own, I would like to build a Infra-Red Remote control >receiver (for regular VCRs and TVs remotes).  Does anybody have any info >or tips on how to build such receiver ? >In particular, >a) which photo detector should I use (which wavelength do remotes use) ? >b) which ICs or circuit should I use ? >c) any suggestions for circuit layout  >Please reply to this group (if you wish), but as well via e-mail (my >link to usenet is not always available).  	I'd like to see this info as well.  As for wavelength, I think you're primarily going to find two - 880 nM +/- a bit, and/or 950 nM +/- a bit.  Usually it is about 10 nM either way.  The two most common I have seen were 880 and 950 but I have also heard of 890 and 940. I'm not sure that the 10 nM one way or another will make a great deal of difference.  	Another suggestion - find a brand of TV that uses an IR remote, and go look at the SAMS photofact for it.  You can often find some very detailed schematics and parts list for not only the receiver but the transmitter as well, including carrier freq. specs. and tone decoding specs. if the system uses that.