cheap mp4 player

[cteno4]

ok we had started a discussion on ffisiv's thread on using an old phone to play video in a building on other mp4 players around. so here is one experiment to that goal.

a couple of weeks ago i decided to try and experiment and ordered a cheapo $7 chinese mp4 player from ebay. these are for cars and take an sd card to do mp3 playback thru the radio and have a small 1.7" lcd screen that is suposta play mp4 videos. for $7 i thought what the heck, lets see if this could get turned into a little video screen on a building.

http://www.ebay.com/itm/290514328881?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649#ht_3158wt_977

well it arrived today and disappointment right away as the car 12v adapter plug was snapped off. got crushed in the mail. we will see what the vendor will do about replacing it.

luckily the power wire was not snapped so i could at least play with it. did fine with mp3 files and displaying jpegs, but took some fiddling to finally get the files into the proper video file format it would recognize. turns out that it only will do AMV format like most cheapo chinese mp4 players -- they dont play mp4 format files. AMV is basically a motion jpeg with very little decoder overhead and low resolution and frame rate.

plays the video decently well, actually mimics a large video display you see on buildings pretty well. only issue is right now at times it shows a big light spot in the top center of the screen some of the time, but this might be due to the breakage and the tape job i did to hold it together putting some pressure on the lcd. been letting it play a while and it seems to be getting lighter and lighter on the screen this may be a real problem.

the unit also has a remote control which was why i was intrigued as this would let you change settings w/o having to access buttons w/in the building. remote works but unfortunately its a bit flaky. i think it may be the ir on it might be very weak, been trying to figure out where the receiver is on the unit.

biggest drawback is that this one has no real instructions with it. ive had to figure it all out by trial and error (and with the flakyness of the controls that can be fun!). they also lied and said it has 1gb internal memory but thats not true. i tried it hooked to a mac and pc with the usb w/o a sd card and no joy of any onboard memory.

once i hear back from the seller about what to do about the busted unit i will see about opening it up. the screen problem could have been some damage to the lcd when it got slammed. it had to be a good crunch to break the lighter adapter off like that. they may offer to send a second and i may just do that to see if the display wash out is coming from the damage on the first or the design of the unit.

all and all its something ok for $7 to experiment with. once i open it up i can see how i might be able to separate the lcd from the rest of the circuitry. sometimes these are soldered or glued together, but usually the lcd is separate with a small jumper ribbon that may allow the lcd to go externally with the guts inside the building. nice thing about these guys is they have no battery and are meant for just 12v power (probably could use 5v thru just the usb if there are no data grounds, ill see).

i havnt played with the pvps for a couple of years here. they are getting very cheap and simple. this makes it something cheap and easy to play with to see what can be done, but it will be necessary to see if these are sturdy enough to bother with as they are made pretty cheaply. there are others for $15-20 range with slightly larger screens and touch screens as well and on up in price and size. goal is to find something thats inexpensive and easy to throw into a building and not have to have a lot of electronics skills to do it.

next experiment are a couple of $3 keychain photo frames that should be here this week. hoping these will work well for doing a station schedule sign that can have times and destinations and adds change with time. might also be interesting for an advertising sign as its brighter than a printed sign even if not motion. would be great if they could fit onto the side of an advertising truck, but i think these are a tad too large to do this and not the right aspect ratio...

cheers

jeff

[Mr Frosty]

The photo key chains have to be worth a go at only 99C each.
Might get one of those to play with.

[The_Ghan]

That brand name, TOMTOP, is purely coincidence, right?

Cheers

The_Ghan

[cteno4]

thats not the brand name thats the name of the store selling on ebay. tomtop is a chinese electronics wholesaler. stuff like this is totally no name cheapo chinese stuff. not getting any sort of a brand name for $7...

why does tomtop has some other meaning?

jeff

[keitaro]

tomtom

[The_Ghan]

Hi cteno4,

Since you raised this thread I've been considering getting one of these puppies for my car.  I'm using a Samsung Galaxy SII phone and need something to get the music from the phone to the car, without ruining my bluetooth phone connection.  Therefore, I have the following questions:

1. Have you tested this thing with your car FM and, if so, is it any good?

2. Can you use a USB stick instead of a SD card for MP3 content?

3. If you plug it into a PC can you navigate to the music folder and play music using the FM Transmitter controls?

Cheers

The_Ghan

[cteno4]

Hi cteno4,

Since you raised this thread I've been considering getting one of these puppies for my car.  I'm using a Samsung Galaxy SII phone and need something to get the music from the phone to the car, without ruining my bluetooth phone connection.  Therefore, I have the following questions:

i would go with a better quality fm transmitter. check the ipod sites for reviews of the ones that use the audio jack, they will work with any device with a standard headphone jack. the reason i say check the ipod review sites is they have a lot of reviews and most of the fm trnasmitters have issues of one sort or another. ive tried a few fm transmitters over the years and none has worked very well. luckily i dont drive enough to worry about using mp3 players in the car, i just burn cdrs of albums to have copies in the car if i want more than the radio and dont care if they get ruined (although ive had cdrs in the car now for like 7-8 years and they still play fine!)

cheap audio jack fm transmitters start at like $5-10 and go up from there, hence check out the reviews. cheap ones i think will be a crap shoot depending on how much an audiophile you are. these fm transmitters will always sound like an ok (not great) regular fm radio station. also depending on the local radio stations, some transmitters will have a hard time finding a good transmitting freq.

this model i described here is not one you can plug a phone into. you plug in a sd card with mp3 files on it and the unit plays them via the transmitter to the car radio.

1. Have you tested this thing with your car FM and, if so, is it any good?

no i didnt test it, but i did notice when i first tired the unit in the car quickly that the radio was doing some popping. not sure what channel it was tuned to or the transmitter was set to, but it smacked of widespread noise, not a good sign.

2. Can you use a USB stick instead of a SD card for MP3 content?

no only a sd port on this along with a micro usb that is not meant to interface with a usb drive, but with a computer. most all cheap consumer stuff with a usb port will not recognize usb memory sticks, they are meant to interface with a computer. ive seen a few higher end things that will recognize a usb memory stick (like some tv av players), but this sort usually on can communicate on usb with a smarter device that is doing the driving.

3. If you plug it into a PC can you navigate to the music folder and play music using the FM Transmitter controls?

The only thing that happens if you plug it into a computer via the usb is that it turns into a sd card reader where you can move stuff on/off of the sd card using the unit as a reader. the unit does not see anything past the sd card, it can only play stuff off the sd card. this is true of most players like this. you can use a regular fm transmitter to broadcast from your pc by just plugging it into the speaker port and using any mp3 player software to play tunes in the background.

cheers

jeff

[The_Ghan]

Thanks cteno4,

Very helpful reporting ... I'll go and get something with a label, like a Belkin or the like.

Cheers

The_Ghan

[cteno4]

Ghan

Do look at some of the reviews though as some of th $$$ name brands are pretty poor. Don't expect to get cd quality, at best its middle fm radio quality.

Jeff

[cteno4]

ok an update. the seller is sending a new unit and does not want the broken one back so i could tear into it. turns out that its a pretty good form factor for mounting into a building. the lcd is attached with a flex pc connector that can give about 1cm of play. the lcd is about 3mm thick, so would not be bad to mount on the outside of a structure with the rest of the board inside the building. SD card drops down to the bottom of the display so thats the only item you need to get to inside the building potentially later. if you need it to point up just mount the unit upside down and rotate your mp4 video in post.

at about 46mm diagonal that translates into an almost 7m diagonal display, thats pretty respectable size for a smaller building.

this unit does have a remote which is the big plus as you can turn it on and turn it to video and turn it to repeat all videos via the remote. take all of about 20 seconds to do this setup. no real way to automate this. i guess you could use one of the ir remote programmers and grab the codes and then try to sequence them out on a programmable ir remote system, but seems like way too much trouble. again the issue is most consumer things like this you find cheap will not have a power on setup to play all videos repeated. mpeg playback units that can do auto set up like this start at closer to $100 and you will need an lcd display that can take ntsc or vga input...

ive had it run for several sessions for like 4-10 hours. does get a bit lighter with time. one thing is that i found one of the barrel capacitors gets very hot with time. thinking ill try a slightly lower voltage and amperage power supply to see how that works. 12v is convenient though for having it fed off of an aux 12vdc power bus for lighting and other stuff.

the video on this unit is still a bit bright/washed out. it also has a light spot in the top center that seems to get a bit worse with time. both of these issues may be due to it getting stomped in the mail so will have to wait to see how the replacement looks. the bright spot got much less noticeable when i tore the board out of the broken casing, so im thinking that one of the shards from the cracked off auto power plug squished the lcd in the case and may have caused this. o

overall though, it plays pretty well. i can also pull the brightness and contrast down some in quicktime and re-encode into the AMV format. it could be the AMV transcode that is doing the lightening as well. video of the screen is a bit more washed out than it really appears due to the lighting.

<a href="http://www.youtube.com/v/G3l79xYyjLw" target="_blank">http://www.youtube.com/v/G3l79xYyjLw</a>

ill post as soon as i get the replacement to see how its display is (hopefully not smashed). im thinking if the replacement works well ill pick up a few and mount into some buildings.

pictures below with 1cm grid. display is funky due to the digital camera only grabbing part of the scan.

cheers

jeff

[CaptOblivious]

Aluminum electrolytic caps (barrel caps) are sensitive to high temps. If they are getting hot, expect them to fail, perhaps explosively. I would consider replacing them with better caps for a longer life.

Anyway, a look inside the guts is quite interesting! What's under that tape, and on bottom of the PCB? I bet these things could be hacked to do interesti.g things....

[cteno4]

capt,

that was my worry as well with the cap. im going to just let this one run on and off for a while to see what it does while im around. it will be interesting to see if the new one has the same issue. i bent the capacitor out from the board a bit and it seems to be running cooler now, ill see after an hour of play. the one that gets hot is the one in the center top there, the other electrolytic does not get warm. any suggestions for a replacement?

the black tape is just double sided foam tape to stick the lcd down to the back of the circuit board.

btw this unit also does mp3 so could also be used for supplying some audio scape sound around the building at the same time as well.

cheers

jeff

[cteno4]

ok bending the cap up some has helped on the temp. its warm, but you can still hold your finger on it. the cpu is warm, but not super hot, as to be expected.

i have to get a ir probe here. they are so dirt cheap now to test stuff like this!

jeff

[KenS]

What's the voltage rating on the cap (should be printed on it)?  A hot cap makes me nervous.

The usual rule of thumb is the rating should be 1.5x to 2x the actual voltage for safety. And as Don noted, when they fail it can be dangerous to things around them, like you. And they fail fairly quickly if hit with an overvoltage.  Be careful.

[CaptOblivious]

Looks like a crap solder job on the hot cap. A bad solder connection could cause it to overheat, might consider hitting it with an iron?

I'm more and more intruiged by these little devices. Color TFT displays, even with basic touchscreens, are getting to be very, very cheap, and I've been spending a lot of time lately specing out parts for the hand-held throttle I'm designing for Railstars. Any chance you could make out any kind of part number on the display or the ribbon cable attached to it? What about markings on the MCU?

[cteno4]

yes i think that may be the issue is the joint on the board there. its now fine on temp once i bent it back the other thing is the metal top was resting against the coil just above it, but i dont think shorting. ill hit the joint with the iron to refuse it. its right on the power ground lead as well. i also have this plugged into i think a 2A 12v supply which is way overkill, but thought it would be fine as in a car its got more amps than that in the cig lighter. ive had electrolytic caps go pop on me in the past!

its actually been playing better, not as light as it was so the cap bending may have helped this. again this one got stepped on in shipping so im thinking its just one to experiment on. ive run it for maybe 36hours total now and still trucking along. goal is to have it running while im working to keep watch on how long they last. new one should be here in a week or so and ill mount that one into a building. the ir receiver is pretty sensitive, im hoping that the windows in the building will let in enough to let it work w/o having to unsolder it and relocate it at a window.

while looking around at a lot of these cheap car and portable mp4/5 players ive found 3 car players in the 1.8" size that have different button arrangements, but i think use the same basic guts (just a different pc board configuration for the buttons probably) as i have found pictures of all three showing identical menu and playback screen features. also a couple of pocket mp4/5 players again with different button configurations, but the same menu and playback screen features. so it appears to be a chip that folks just build around that has all the basic playback features.

a couple years ago at an A/V conference i was at i saw the coolest micro OLED screens. they were like 32x32 to 128x128 in size and built into various control buttons. was way cool you could have a keypad that you could have custom graphics on each button and have them change on the fly. the guy was saying they were getting them to the point they could be programmed and then always power on with your desired graphic. would be wonderful to have a dcc controller that had picture buttons or a little oled screen the picture of the train on it!

the touch screens have also just gotten everywhere. even a couple of years ago i was getting 7" touch screens that were 640x480 with a dedicated mpeg/jpeg playback system (from flash cards) for like $125 each w/o housings. these are perfect for doing a little audio station as you get simple 10 zone touch screen response and a simple programming system to flip between jpegs and movies. you could create a simple little menu tree of button screens and then have them show movies or graphic/text while your audio played. turned out much faster use these and program a station with 10-15 audio clips than do it the old way with physical buttons as the process for doing the physical graphics for the panel was a bitch and if you made one mistake in the process you had to start over! this way we also got a couple of paragraphs of text to go with each audio clip which we would have never had room for on the panel!

heres picts of the processor and the text on the lcd ribbon cable. i removed the back of the lcd panel and there was nothing there on it.

cheers

jeff

[KenS]

The amperage of the supply won't have any effect.  That's just a rating of how much power it can supply when needed.  As long as it's more than what you need, 1 amp or 1000 amps is just the same. Caps have a problem with high voltage.

Well, a big cap wired without a limiting resistor or similar can draw a huge current at startup, and that can cause a small supply's protection to kick in, but that's not what's going on here. That was a problem with early DCC sound decoders that had a big capacitor and no limiting.

[cteno4]

its a 35v 22 microfarad. its odd as i notice sometimes it will get hot and others not.

jeff

[keitaro]

Don't suppose you can tell me the approx minimum voltage / amp required to get this going.

I was planning a small solar farm wired together to power this up as an advertisement board on road side.

currently i can get enough power with my prototype setup (6 cells) to power tomix track to move the train ever so little to none.(room light) If i open the blind it gets a touch better.

I am using cells 3cm x 1 cm.

I was going to add a larger cell 5cm x 2cm to the free space at the farm to boost this higher and another on top of a house.

wire it up to make it look likes it's for the house run down under the table and get a switch to turn the solar on / off to the screen.

i'm assuming even with this setup i probably won't get enough power (indoors definately) maybe with sun light i could.

[cteno4]

Keitaro,

no not easily, dont have a variable power supply handy that i could try amperage tests. its set up to take 12vdc from a car so i expect they designed it to be getting 12v, not a range like from a battery source. i can try and slap it on some lower voltages via a kato power pack. i expect its not huge amperage, but again i doubt its made to be super efficient like a portable device as its designed to plug into a car lighter and get lots of amps at 12vdc.

why the need to run this from a solar cell? i can see it fun to have operational solar cells powering something, but probably better to to have accessories like this powered via a 12vdc buss.

wind mill might be the better thing to power via the solar cells. the one i have would probably work with 2x or 3x the solar cells to turn it under room light. works great under sunlight, but not under room light.

hopefully the replacement will be here this week and i can see how well a non stomped version works. i have not found many other alternatives up this route that is cheap and has a remote for easy set up.

jeff

[keitaro]

yeah it was more the fun factor to power something completely running off the solar cells.

Call it a "Green Feature" of the layout lol.

I would like to power a lot of things from the solar cells but obviously this is unpratical to the extreme especially under night scenes.

[cteno4]

yeah i tried a few little cells to perhaps keep some batteries charged in structures to run led interior lighting, but found they just wouldn't put out enough to even keep small cells charged under normal room lighting...

for the scene its easier to print out the solar cell pattern on and face with acetate (or print on acetate and put the print side down) and frame to make the panels for roofs and farms than trying to get the available real solar cells near to scale and look right. real panels are like 6-12" thick at most in a housing so thats like 1-2mm thick total.

cheers

jeff

[keitaro]

yeah these cells i got a 1mm thick. again it's more for fun i'll probably not end up implementing it but fun to play around.

[The_Ghan]

Don't suppose you can tell me the approx minimum voltage / amp required to get this going.

I was planning a small solar farm wired together to power this up as an advertisement board on road side.

...

Now that sparked a thought ... has anyone ever done a green layout - ie: self-powered using wind and solar - N-scale, of course.  I think THAT would make a tops competition project.

Cheers

The_Ghan

[cteno4]

Shashinka ran some trains from a solar panel he had when he use to work for bp solar.

He even made a PDF for a paper model of the standard bp solar panel in n scale. I'll see if I can find it.

Jeff

[cteno4]

Well good news bad news...

Good news, got the new unit the other day.

Bad news, plugged it in and it turned on for a few seconds, then went pop and dead... Not sure that it's worth pushing for a replacement at this point for a $7 item. I did find a place that ships from NYC for like $7.89 so may try that for another one.

The first unit with the busted case is still working fine, the one cap still runs a tad warm, but has played fine for like 40 hours of play now. Ther is still the light spot on the display but I do think thats from the stomping it took. Hopefully a new unit will prove tha...

Jeff

[keitaro]

Well good news bad news...

Good news, got the new unit the other day.

Bad news, plugged it in and it turned on for a few seconds, then went pop and dead... Not sure that it's worth pushing for a replacement at this point for a $7 item. I did find a place that ships from NYC for like $7.89 so may try that for another one.

The first unit with the busted case is still working fine, the one cap still runs a tad warm, but has played fine for like 40 hours of play now. Ther is still the light spot on the display but I do think thats from the stomping it took. Hopefully a new unit will prove tha...

Jeff

does the screen plug in out easy maybe the new busted one can be swapped over at least? assuming the screen is not the fault..

[cteno4]

no screen ribbon is soldered on and its such a cheap unit and massed produced so no real reason to replace parts. pretty much disposable level at $7... thats makes it good and bad. good to play with and not waste much money if something goofs, bad as they are not made all that robustly and everyting is soldered.

i can use the blown one to practice unsoldering the ribbon, wanted to see if thats a possibility. some solders like that are really tough to unsolder so i can experiment.

jeff