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Post by Boomer on Dec 14, 2018 18:54:49 GMT
Another posting started a discussion on outdoor projected movies and drive-in theater sound through AM radio. How common was it to use a low power radio station to broadcast movie and intermission sound to cars at a drive-in? It seems like most theaters have done it, especially as their pole speaker systems and wiring had fallen into disrepair, small transmitter technology became available, and solid state radios came to cars, so tube sets wouldn't drain car batteries during a double feature. Most drive-ins today broadcast only on FM, but I found Benjie's Drive-In in Maryland (with my K-9 avatar, I like that name) that's on both AM and FM, so it's great if you have a classic car with only an AM radio and want an authentic movie viewing experience. They use 106.9 FM and AM 830 for the sound. www.bengies.com/about/Look under 'Little Has Changed' and at the FAQ for radio info. Cine-Fi by Meieei(?) Electric Co. Ltd., was one of the transmitter manufacturers for drive-ins. This drive-in history page from Australia talks about Cine-Fi as a tech improvement. aso.gov.au/titles/collections/drive-ins/I guess it's sensitive to high pressure sound waves.. Cine-Fi was one of the AM transmitter types I found marketed to drive-ins, and LPB also marketed them to outdoor theaters, as did Broadcast Warehouse on the FM side. Boomer
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Post by Admin on Dec 15, 2018 3:52:35 GMT
Friend of mine was a projectionist at the East Drive-in, Tallmadge Ohio many years ago.
He told me he installed an LPB (AM TX) at the drive-in for their in-car movie sound.
Rather than carrier current or leaky co-ax, he ran an antenna wire from the projection booth to the top of the screen.
Even at lowest power I'm sure you would hear that at a distance from the drive-in.
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Post by End80 on Dec 15, 2018 4:10:53 GMT
I took a quick look around and found a thread at the Film-Tech forums where someone asked: "Who has experience working at or attending drive-in movies? I'm wondering when was your first encounter with "radio sound" (Cine-Fi, etc.) as opposed to hanging a speaker on your car door?..." Here are some of the replies or excerpts of, describing different setups going back as far as the late 1950s. These are the ones I found most interesting, some even specifically mention part 15: ----------- Louis Bornwasser from Prospect Kentucky: "I used the LPB am transmitter in 1970 in a 1600 car drive-in here as a test. Owner would not buy it because he felt the car batteries would not start the car at the end of the night. FM was slower because part 15 did not originally apply to FM...." -------------- John Pytlak from Rochester NY: "When I worked at the Grandview Drive-In in Angola NY, I built a home brew AM transmitter in 1968 that was coupled to the underground speaker wiring. About half the audience preferred the AM radio sound, event though plenty of speakers were available on the lot. We played several films in "stereo" using the in-car speakers for one channel, and the AM for the other: GWTW (remix), "2001 A Space Odyssey" (during the week of the Apollo 11 moon landing in July 1969) and "Funny Girl". Biggest problems at the time were nightime interference from Radio Havana on the frequency we chose (640 KHz), and older tube type car radios running down car batteries. We always had jumper cables handy for the dead batteries. " ----------- Mitchell Dvoskin West Milford NJ: "Carrier Current AM was legal from the early 1960's on. It allowed you to broadcast though electrical wires, and to be legal, could not be picked up more than 30 feet from your property. Many Drive-in's and college dorms used this format. I was involved with the Paramus Drive-In (Paramus, NJ) in 1980-1981, and we had an illegal stereo FM transmitter that we broadcasted the left / right from our Dolby CP-50. You could pick us up on the Garden State Parkway, ¼ mile away. I believe low power FM was legalized somewhere in the late 1980's." ----------- David Kilderry from Melbourne Australia: "Here in my part of the world all drive-ins were 100% speakers until 1978. At this time the Village Drive-in circuit upgraded to Cine-Fi AM. They removed most of the speakers, but found many had to be returned as many did not have radios and the old Blue Cine-Fi hire radios were soon wrecked or stolen. The opening films here in Melbourne with Cine-Fi was the Grease + Saturday Night Fever double..." ---------- John McConnel from Okmulgee, OK: "The Riverside Drive-in in Norman, OK, had radio sound in 1959, as well as field speakers. It was an AM system, built by J. Eldon Peek of Oklahoma Theatre Supply in Oklahoma City. The antenna was a wire stretched horizontally between posts behind the back ramp..." Concerning the Cine-Fi system...
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Post by End80 on Dec 15, 2018 4:15:08 GMT
And at that same thread, Jack Ondracek from Port Orchard, WA, went into great detail about the Cine-Fi system you mentioned....
"The Cine-Fi system is/was a package of rack-mounted components, which could be mixed and matched to fit your theatre and budget. If you had a working speaker system, and wanted to eliminate speaker maintenance and replacements, Cine-Fi was the way to go. It was like the LPB systems, except it was designed to work with your existing speaker wiring, instead of leaky coax. As most of Pacific's drive-ins were paved, I can see how a system like this would have been attractive to them.
The system was provided in both full-sized racks and half-sized open "relay" racks, usually on wheels. The transmitters were 10 watt units, which were designed to feed into a "splitter" box. That box had screwdriver-adjustable pots that let you feed a portion of the transmitter's output to each of the theatre's existing rows of speaker boxes (the speaker wiring hooked up to the splitter). Some installs had a monitor of sorts, which would include an automotive AM radio, a 12v power supply and in some models, a small oscilloscope for adjusting modulation levels. A CB-type microphone allowed for paging, and there was a tape deck input for "non-sync". Larger installations could be purchased with emergency standby transmitters and switching panels to route input audio and ouput RF lines.
The system was literally self-contained. The sound-head solar cell connected right up to the transmitter, which had mic-level inputs for the projector and paging mic. Given the vintage and intended use, there was never any accommodation for noise reduction. After replacing the outside speakers with antenna clips, installation was more or less complete. At one point, all of Pacific's drive-ins in Washington State, and maybe even in California used this system. The sound was roughly comparable to what you'd get from a window speaker, which was a shame, because most AM radios back then could do much better.
..In Japan, somebody had a building with an elevated parking lot. There was an activity of some kind there... can't remember if it was a drive-in, though... maybe. Anyhow, poles and speakers were out. Somebody there came up with the idea of sticking an incredibly low RF level into a wire with a clip. You clip the wire to your antenna to get the sound. In practice, some radios can pick up the signal without the clip, but a lot depends on evening skip interference.
Somehow, someone at Pacific Theatres got wind of the Japanese system and sponsored/imported/licensed its use in the US. Inventor Kiichi Sekiguchi (then of Cine-Fi International) received the 1978 Technical Achievement Award for the development of the CINE-FI Auto Radio Sound System for Drive-in Theatres
By today's standards, Cine-Fi is pretty seriously outmoded. Of the two transmitters they made, one had a vernier analog tuning dial... really great when transmitting to today's PLL-locked radios (the transmitters drifted horribly with changes in ambient temperature). They didn't have any processing, either... not even basic limiting. You'd have to add a lot of outboard processing to make it sound very good. Some of the parts in there are pretty hard to come by, if you can find them at all.
As for FM in the '70s, there weren't many options, other than being lucky enough to have an "in" at a radio station with a good junk box. As for the 'do it yourselfers', did Broadcast Warehouse, Ramsey, Decade or Panaxis exist? Mr. Microphone, maybe [Smile] .
Shown below is a Cine-Fi installation, currently in use at the last "United Drive-Ins" location in Washington.
From top to bottom are: The monitor panel (note the car radio at the upper right).
Two of the "newer" transmitters (dip switch frequency set with frequency readout, audio level and RF meters).
The "input panel", where source equipment is connected and leveled.
Finally, two versions of output splitting panels, to which the former speaker lines are connected.
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Post by End80 on Dec 15, 2018 4:37:30 GMT
Hmm.. no I guess I didn't read the FAQ.. (where is the FAQ?)
Anyway, here's an interesting 2001 patent application for "Drive-In Movie Theater with Short Range Sound System" which apparently utilizes part 15 and was also intended for use in shopping center parking lots. The patent was granted in 2011 but apparently abandoned... I can see why, it seems to me it would be problematic. A single part 15AM transmitter would make more sense. patents.google.com/patent/US7266927
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Post by End80 on Dec 20, 2018 15:03:58 GMT
Found this video
September 6, Oddity Archive Episode 155: The Archive Drive-In Movie Theater (or, more fun with Part 15 microbroadcasting) Description: 2018 - Attempting to realize a viewer’s vision of an old-school, drive-in theater—at home.
The video is about a half hour long, and to be honest pretty boring. I didn't have the patience to watch it in full and just kind of jumped thru the video.. after about 20 minutes he finally gets to demonstrating with a 16mm film projector and a Radio Shack part 15 FM transmitter, which is basically the same setup I used, only mine was an AM transmitter. He seemed to be having a lot of trouble getting the sound right.. in reality it's not nearly as complicated a process as he was making it out to be. It's not complicated at all, it's actually pretty cut and dry thing to do.
I just figured I'd post the link since it's on topic, although it's a very poor presentation.
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Post by Boomer on Dec 25, 2018 6:28:00 GMT
Stretching a wire between the projection building and screen would seem to be an alternative way to broadcast to cars, compared to the trials of loading into the underground speaker wiring, and maybe using a clip lead to the car's antenna.
The horizontal wire antenna in the air over the cars would be less complicated and require far less power. From tests the signal under the wire should be strong, but with the wire being horizontal, that cancels the signal a great deal, so it's well controlled. The solid state LPB transmitters can be turned down to almost nil power also, at least the one I use does.
I wonder how many drive-ins just use one of the whip on mast transmitters at the main building? If run at the bottom of the AM band, it might give enough signal to the cars, without going out of the grounds too far.
End80. Great info on Cine-Fi, and the abandoned patent, for a scenario like Walt Disney would have thought about in the 1950s for the 'city of the future.'
I might have more comments later, but here's hoping you can do a blog about this, if you are looking for topics to write about there. I have full Cine-Fi manual as a PDF if you're interested in having it. The scan is pretty low quality, at least the schematic is hard to see, but it still might be informative. I got the file some years ago, and wasn't able to find it on search nowadays to post the link.
I find drive-in radio transmission an interesting topic, any low power radio really, something most people just don't give much thought to, 'there's a radio station here and I can tune it in at the drive-im', they just accept that it's possible, but it's a concept that fires my imagination.
Boomer
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Post by End80 on Dec 25, 2018 7:21:22 GMT
...I might have more comments later, but here's hoping you can do a blog about this, if you are looking for topics to write about there. I have full Cine-Fi manual as a PDF if you're interested in having it. The scan is pretty low quality, at least the schematic is hard to see, but it still might be informative. I got the file some years ago, and wasn't able to find it on search nowadays to post the link. I find drive-in radio transmission an interesting topic, any low power radio really, something most people just don't give much thought to, 'there's a radio station here and I can tune it in at the drive-im', they just accept that it's possible, but it's a concept that fires my imagination. Boomer I'd like to do a blog post about it, but if I do it would want it to be for the most part be part 15 specific. I've heard so many mentions about drive-ins being done with part 15 but have found nothing which actually confirms it, nor of any hobbyist who've done it other than myself. I know there are pictures floating around of some of my own impromptu drive-in type settings using 16mm projector and my transmitter, cause I've seen people take pictures on several occasions, but that was years ago and wouldn't have a clue how to track them down..
I actually have vague memories as a child of our family sitting and listening in the car at a campground while they screened Yogi Bear and other cartoons on an outdoor screen, I'd love to find some kind of documentation of that. I don't remember if they were KOA or what, but being in a military family, every five years or so we moved to another state, or sometimes just a trip to Tennessee to vista the grandparents, and those trips were always made by car with mom, dad, and us five kids, and our stops for the night was usually campgrounds. I could be wrong but it seems it was on more than that one occasion that campground movies was a part of those trips.
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Post by Boomer on Dec 25, 2018 11:49:30 GMT
Yeah, I never stopped to consider that drive-in theaters might be operating under Part-15, I'd always assumed that they were, and have heard of them being lumped in with P-15 use when articles talk about low power radio and where you might find it.
I see the possibility of it being something else though, being that outdoors are a commercial business, and would seem to want to conduct themselves more professionally and have the full assurance of the rules, and the companies that make equipment for use under those rules.
Then again, schools have used carrier current professionally under Part-15, and that seems to work out. Interesting.. something to look into.
Radio for movies at a campground sounds like a great idea, and likely at a campground there would be more open frequencies to use. A movie to send off the kids to sleep, and the sound right there on the car's radio, a must, since you wouldn't have the speaker poles that a drive-in would have.
Boomer
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Post by End80 on Dec 25, 2018 13:10:52 GMT
Found this article in the Washington Examiner June 2009, it's called "Impromptu Drive-In Movies Resurrect the Past", about a guy who projected about a dozen movies using a 16mm projector mounted on the back of his motorcycle at some historic fort, for some group of paranormal investigators, and the audio was received on FM radios. This obviously was a part 15 setup..
www.washingtonexaminer.com/impromptu-drive-in-movies-resurrect-the-past
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Post by End80 on Dec 25, 2018 13:56:09 GMT
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Rich
Full Member
RF Systems Engr (retired)
Posts: 112
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Post by Rich on Dec 25, 2018 19:55:17 GMT
Decade advertises their Drive-In transmitters (FM) with an adjustable range of coverage of 1500 to 5000 feet radius. ... Are such devices permitted under Part 15? A useful range radius of several thousand feet is unlikely from an unlicensed FM setup permitted by 15.239, and neither campus broadcasting nor "leaky cable" is authorized for unlicensed use of the FM broadcast band.
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Post by End80 on Dec 25, 2018 20:32:38 GMT
Decade advertises their Drive-In transmitters (FM) with an adjustable range of coverage of 1500 to 5000 feet radius. ... Are such devices permitted under Part 15? A useful range radius of several thousand feet is unlikely from an unlicensed FM setup permitted by 15.239, and neither campus broadcasting nor "leaky cable" is authorized for unlicensed use of the FM broadcast band.
Sorry for the confusion; No, neither the Decades nor the BW Broadcasting transmitters are part 15, they are just the kind of low power FM transmitters which are being marketed to existing drive-in theaters nowadays.
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Post by End80 on Dec 25, 2018 20:39:08 GMT
Now that I think about it, the above fair grounds article couldn't have been part 15 either (nor did the article say it was), because it probably wouldn't have been sufficient to cover an area of 70 parked cars.. Part 15AM would have though.
.... Well, now that I think of it again, maybe the fairgrounds was part 15FM and they just used multiple transmitters. All the article said is that the audio was on 107.7, so I don't know, it was just an assumption.
.. or maybe it was just 1 part15FM transmitter which was over powered.. who knows?!
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Post by mark on Dec 26, 2018 1:18:33 GMT
Those Decade transmitters in question are not part 15 or BETS-1 certified but are certified for other categories of use that need licenses. But as I recall drive ins are a separate category of use and for these transmitters NO license is needed in Canada for drive ins. Note that these transmitters are legal here(Canada) they are not in the USA. Not even for drive ins.
Check this out from Decade....http://www.decadetransmitters.com/en/radio-licences.htm
Oh, I will correct myself. The Decade FM 800/850 can be used in the USA for drive ins with out a license. Guess it has been approved for that application only.
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