Recommendations for hardware at Drive In
May 28, 2020 12:34 PM   Subscribe

Hi all, I'm looking for an answer about what kind of accessory I should pick up to plug into the AUX hole of my speaker at a drive in movie theater in order to make it pick up the (possibly weak) signal of the theater.

So, first off, I don't really understand how cars, radios, or anything else works. I like seeing movies and since I can't go to theaters for the foreseeable future, but still want the experience of seeing a Drive In movie, I've been going to a place in San Jose, CA called the Capitol Drive In. Really like it, but I'm paranoid about my car battery dying on my Toyota Prius, because basically any time that I go there, some not-so-old car battery dies and it's a whole thing. So, to prepare for the double feature this past week me and my socially distanced friend in a different car BOTH purchased different radios in order to play the music not on our car stereo.

He picked up this old school one which has a three foot antenna attachment:

And I picked up this newer looking guy which has a much harder to navigate radio setting where you basically just scan the stations and plug in an AUX cord as an improvised radio antenna:

Funny thing is that both of our radios didn't work, only picked up a distant screen on the other side of the parking lot for Trolls World Tour (ugh), which is fine, but definitely not John Williams's soundtrack to ET. Anyway, friend turned on his car radio (which picked it up fine). His car battery died by the end of the first movie and we needed to get a jump from the owners before the start of Jurassic Park. I streamed the entire movie on my phone and played the audio into the boom box, which also feels incredibly lame.

I get the sense that I might be able to solve this problem with an FM transmitter or something maybe? But, like I said, I have no idea. Obviously the car radio was stronger because we heard other people playing it in their cars, but I want to avoid that preferably without buying a new radio. Thoughts?
posted by ABlanca to Technology (9 answers total)
You don't need an FM transmitter. The transmitter is what the drive-in is using to send you the audio signal for the movie. If your car radio picks it up then the signal is available, and you just need a way to receive it, i.e. you need a radio. The unit you bought has a radio, but didn't work as expected. Maybe the signal is weak, or maybe your radio is terrible, or maybe your radio is broken, or maybe you're doing something wrong.

The manual for the unit you linked to includes this instruction:
Under FM radio state, the audio cable provided treat as antennal [sic]. Please insert the audio cable to get the best FM signal before using.
Did you insert the provided audio cable?

If you want to use the car's radio, be sure the ignition switch is in the ACC postion, not the on/run position, and make sure other electrical draws like lights and fans are all turned off.
posted by jon1270 at 12:57 PM on May 28, 2020 [4 favorites]

Can you listen to FM radio in your car under regular circumstances?

Also, you have a Prius. All you need is enough of a jump start battery to get the relays working and your big hybrid battery will recharge your little accessory battery, in the unlikely event your accessory battery dies.

(That does seem like a lot of dead batteries, for cars with their lights off just playing the radio. This is not typically a problem at drive-in movies.)
posted by Huffy Puffy at 1:20 PM on May 28, 2020 [2 favorites]

That does seem like a lot of dead batteries, for cars with their lights off just playing the radio.

Especially in an older car, a couple of hours with the ignition key turned to On instead of to Accessories can be enough to drain a marginally working battery. With the key turned to Acc, a car battery in almost any condition should be able to run a radio at reasonable volumes for many hours unless the car is wired in a way where Acc enables some heavy feeder like a rear window demisting element that's accidentally been left on.

As for the signal strength thing: last time I went to a drive in theatre, there was a little clip on the end of a wire that had to be stuck onto the car radio antenna to deliver the signal. Not sure why they do it that way - perhaps it's a broadcasting licence issue, or perhaps they're trying to discourage nearby freeloaders from just perching somewhere they can see the screen without paying and still getting audio - but that's how it worked.
posted by flabdablet at 2:01 PM on May 28, 2020

+1 on flabdablet's comments. I think part of the problem may be that the body of a a car is basically a giant faraday shield (since it's mostly metal.) Car antennas are external (either a whip antenna in older cars or a metallic element built in to the glass on newer ones) and so the shielding aspect of a car doesn't affect them. The other thing is that most newer, lower priced portable radios have very poor sensitivity. There are also FCC power limitations on the transmitters used in drive ins, so the transmitted signal may be weak even though you are relatively close.

Once parked, how about sticking the radio on your roof and then running a headphone style extension cable to some headphones you wear inside the car? Would just be a couple of bucks for the cable. Might work, might not. Did you see if the radio would work outside the car at all?
posted by Larry David Syndrome at 2:10 PM on May 28, 2020

On further examination, the speaker you bought doesn't appear to have a headphone socket, so my idea won't work with what you've got. It may work fine with a different radio, though. I'd really focus on buying something that's a radio first, rather than a bluetooth speaker which has some radio functionality added in as an afterthought.
posted by Larry David Syndrome at 2:15 PM on May 28, 2020 [2 favorites]

You should check your car's manual to see how to turn the radio on without the car on. If your batteries aren't lasting a couple hours, you are doing it wrong and you're turning on other things that you don't expect. The days of a key that you turn to the ACC marking (or earlier, just knew to turn it back toward you instead of forward) are over, as cars now each have their own crazy user interfaces with wireless dongles and pushbuttons and biorhythm sensors and cell phones and laser beams.

We have two cars which are 15 and 17 years old. In the older one, you can turn the car off with the key in the normal way and pull the key out, but then poke the radio power button to turn just the radio back on. In the newer one (a prius), I think you press the power button without first pressing the brake pedal, instead of with the brake pedal held down, which is the magic incantation required to make the car go normally. I think the little light that's (of course) on when the car is off but off when the car is on turns a different color. But I would have to check the manual to be sure.

So you can see I can declare confidently that this WENT ALL WRONG in 2004. I am sure it's much worse on newer cars. It's madness. But I am also sure even newer cars can run the radio for a few hours if only you can figure out how to tell them to do that.

I feel so old.
posted by fritley at 2:34 PM on May 28, 2020 [2 favorites]

Best answer: I'd start with a small portable FM radio with an antenna, like this or this, both under $16. Take a drive by the drive-in some night and see if you can pick up the the screen's signal-- call the drive-in if you don't recall the frequency. If it works, connected the headphone jack to the AUX of your speaker-- done. Have some spare batteries for the FM radio-- I don't think it'll run out in 2 hours of use on fresh batteries, but it's possible either of those will come with batteries that are very far from fresh.

I wouldn't sweat the battery in your Prius-- the car has more battery than engine.

The ultimate backup is a spare car battery which will sit in your trunk or the other person's, along with the tools ready to drop it into place. The other driver may need a new car battery anyway if it dies that quick running only the radio-- (but if the heat/AC was on the whole time, well, that's another story). They should get it checked, because car batteries in my experience seem to have a suicide pact with the alternator-- when one goes, it can take the other with it.
posted by Sunburnt at 2:39 PM on May 28, 2020 [2 favorites]

My cell phone has an FM-radio app; maybe yours does, also.

IMO it doesn't really make your cell phone into a radio (an older appliance which has a built-in speaker) but instead, makes your cellphone into a Walkman - which might be okay, for your purpose. My app won't work unless the headphone is plugged in, because it uses the headphone wire as an antenna. But if you plug your speaker into the headphone jack (if your cell has one) there may be enough power for you to hear the drive-in's broadcast on your speaker.
posted by Rash at 5:07 PM on May 28, 2020

On a Prius specifically, just leave it in Run mode! The engine will mostly stay off, as long as you turn off the HVAC, and the big battery will power the radio through the DC-DC converter.
posted by doomsey at 8:29 PM on May 28, 2020 [1 favorite]

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