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Low-cost Battery-powered portable widescreen DTV

Picture of Low-cost Battery-powered portable widescreen DTV
Use ordinary D batteries to power a small DTV converter box connected to a portable DVD player or handheld TV.

Last September, Hurricane Ike swept through town and just about everyone was without power for days, unable to get news or weather updates. Being a computer programmer, I have two backup UPS (Universal Power Supply) battery backups that I charged up in advance so I'd have *some* emergency power during the inevitable blackout.

When the storm hit, I was able to power my portable TV for a mere 3 minutes before my UPS was drained. My sister took shelter at a friends' home, who happened to own one of those tiny 2.5" battery-powered handheld TV's. My sister noted how helpful it was (and would be) to have one for emergencies, but I reminded her that after February 17, (now June 12) 2009, that handheld TV would be nothing more than a paperweight, as TV stations went all Digital.

I then started looking online for a portable digital TV, which I discovered all cost between $150-$350. Ouch. That's when I started thinking about just plugging a small DTV tuner into a handheld TV. It wouldn't be as "portable", but I didn't care about "portability", just something to provide TV reception during a blackout. If the TV was powered by batteries, I only needed to power the tuner, preferably using cheap off-the-shelf batteries that I can stock up on the next time a storm hits. And once the Digital switch-over takes place, those old handheld TV's are going to become super-cheap as people find they can no longer use them.

To save even more money, I ordered two government $40 DTV coupons online and (after much research) used one to purchase a "MicroGEM MG2000" Digital Converter Box (the smallest unit made) for the most compact package. The power requirements of the MG2000 is only 6.5v. Hoping I could power it with only 6v (four 1.5v batteries), I also purchased a 4-D cell plastic battery holder (only to discover later it just wasn't enough power).

Mostly, this "Instructable" is just about building a battery pack for the DTV tuner. Everything else is done for you. If you find/have a DTV receiver whose power requirement is an *exact* multiple of "1.5v" (6v, 7.5v, 9v, 12v), you can do all this without "building" anything!

I apologize for not having taken any photos *during* construction, but I didn't think of turning this into a how-to until after I was done.
 
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Step 1: Materials:

Picture of Materials:
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rca audio cable.jpg
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1. Low-power Digital TV Converter Box. If you don't already have a Digital TV Converter Box, I recommend the "MicroGEM MG2000", the smallest unit on the market at 4.5" square. It's also one of the top rated units out there. If you can still order one of the free government $40 "coupons", do so asap. The MG2000 is apx. $55 (before coupon).

2. Portable video player, such as a handheld TV. I purchased a used 8" portable DVD player on eBay just for this project for $40. Your device MUST have external "Video In/Out" and "Audio In/Out" jacks. If you already have a portable DVD player or old portable TV, use that and save yourself some money. I chose to use a DVD Player because most have a "widescreen" display (perfect for DTV) and a 3-hour battery pack.

3. ONE 4 D-cell battery holder with "snap terminal" (aka: 9volt style) connector, and ONE single D-cell battery holder with wires. I found the 4-cell holder on eBay for $6 (after s/h) and the 1-cell holder at Radio Shack for 99cents - or try this. (This is what I needed to power the 6.5v MG2000. If you have/buy a different receiver, be sure to buy the correct number of holders for enough batteries to power your receiver.) Be sure to use D-cell holders for maximum battery life.)

4. One 2.1x5.5mm (tubular power connection) to "9v clip" for conecting the "snap-terminals" of the battery holder to the DTV receiver (+ center, - sleave). I found this at a local electronics supply for $3. ("Electronic Parts Outlet [EPO]" part#: RC-9v-2155).

5. Five D-cell batteries.

6. A small piece of wood to mount the battery holders, 7"x3" (1/4" thin is best).

7. Silicone glue for mounting holders to board.

8. Two small machine screws cut down to apx. 1/4" long, with nuts.

9. One thin metal "plate", 1/2" square, with a hole in the middle for the screw.

10. Depending on your video display device, RCA cables to connect the audio/video output of your Converter box to your display. I used a single RCA-to-2.5mm for video and a dual RCA-to-2.5" cable for audio (both found at Radio Shack). The audio cable is easy to find just about anywhere. The single RCA-to-2.5mm cable can be a bit harder to find (Radio Shack part#: 42-2444A - "Audio and Digital-Camera Cable").

11. Rabbit-ears or other small UHF antenna (or Google DIY HDTV antenna).

I already had most of these items, so my total cost was about $65, the most expensive items being the used DVD Player and new HDTV tuner. If you find a tuner for less than $40, it'll be free with the government coupon. And many people already have an old portable TV that would otherwise become worthless after the national switch to DTV in February, taking your total cost down to just a few bucks for batteries and cables.

Step 2: Pre-testing:

Picture of Pre-testing:
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(If you don't need to construct the battery pack because you can get a holder for *exactly* the right voltage for your tuner, this is your only step.)

If your portable DVD player (or other portable video device) has a switch for video In/Out, be sure to switch it to the "In" position. Plug the single RCA-to-2.5mm cable between the yellow "Composite" jack on the tuner and the Video In jack on your video player. Do the same with the Red & White audio cable and the audio jack on your Player.

(I tried this with a different portable DVD player that input both audio & video through the same port. Despite this, every 3RCA-to-2.5mm cable I tried failed to produce video. I solved this by using the *2RCA* stereo audio cable for both video and sound, plugging the Red plug into the yellow video port on the tuner and connecting the white plug as normal. You won't get stereo, but at least you'll get both picture and sound.)

Connect your Rabbit-ears antenna to the tuner. You may need a 300ohm ("horseshoe contacts") connector to 75ohm (cable) adapter to connect the rabbit ears to the "video-in" on your receiver. These are common and found most everywhere. If you're like me, you probably have two or three just laying around the house. They're tiny boxes with a round male cable jack above two screw wire contacts). You can collapse the antenna rods since DTV only uses the UHF loop.

Plug in your DVD player and DTV tuner using the supplied power cords (we just want to make sure everything works first). Turn on the tuner and the DVD player. If all is well, you should see *something* on your player, either TV or the tuner's menu. If this is the first time you've used your receiver, you may need to scan for channels before you can watch TV. Make sure you are getting both picture and sound before proceeding.

Digital TV on your DVD Player. Cool.

Step 3: Procedure for building your battery pack:

Picture of Procedure for building your battery pack:
Take the 4-D cell battery holder. At the bottom, there will be a wire (or some other connection) bridging the bottom two contacts. You will need to snip this so the batteries are no longer in contact with each other. The positive terminal will stay in place, but the negative spring contact will need to be held in place with a piece of metal and a screw. When batteries are inserted, there should be roughly a 3/8" gap where the spring compresses, just enough room for a short screw. There should be holes in the bottom of the battery holder where the contacts are. Insert a screw through the hole. Hold the spring in place with the metal plate. Fasten the spring in place with the nut on the inside and the screw head on the outside of the holder. Insert a screw through the positive side next to it as well, head on the outside.

(sorry for the blurry pic. Close ups tend to be fuzzy, but you can see the metal plate and the screw inside holding the spring in place.)

Step 4: Attach holder for fifth battery:

Picture of Attach holder for fifth battery:
Strip the tips of the single D cell holder wires just enough to wrap them around the two screw contacts you just inserted on the 4-cell holder. Be sure to connect the negative wire to the positive screw contact and vice versa so the power runs through the fifth battery (this gives you a total of 7.5v of power, 1v more than the MG2000 needs, but enough to power the receiver without harming it. 6v isn't enough power w/o the signal cutting in & out, and there is no combination of off-the-shelf 1.5v batteries to give you exactly 6.5v of power.)

Step 5: Test:

Picture of Test:
receiver plugged in.jpg
Now that your holders are wired together, you can test your battery pack before mounting it to the board. Insert the batteries and snap the "9v to 5.5mm sleeve" power connector to the snap terminals atop your battery pack. Plug the battery pack into the DTV tuner and turn the tuner on (the MG2000 goes on the moment you plug it in). Turn on your DVD Player. You should be getting TV. If not, try changing channels on the converter box and moving your antenna until you do.

Step 6: Mount and Done!

Picture of Mount and Done!
If everything is working, turn off the DVD Player and unplug the battery holder from your tuner. Apply a few dabs of silicone glue to the board and affix the battery holders to it. Glue should dry in about an hour. You might want to wrap the holders down with masking tape while you wait for it to dry.

That's it! Now, the next time the power goes out, you'll still be able to watch Digital TV. Especially useful in a storm when you need weather updates. By using D-cell batteries, the unit should stay powered for several hours. And if they go dead, you can easily replace them. The biggest drawback of my particular setup is the rechargeable battery pack on the DVD Player. But if you use an old handheld or portable TV that can run on disposable batteries as well, as long as you have batteries, you've got TV... even after the DTV switchover in February.

Enjoy your new battery powered HDTV!
jpnagle593 years ago
Come on boys, .4-.8 volts makes for not much concern- the box has a filter... Want HDTV? Like Last_Liberal said, it is for emergencies and such. Good thinking LL...if you want HD or Imax, rent a big generator, that way your neighbors can plug into it, and you can charge them for the juice...

Just trying to help here folks, not criticize...

Good point here- if you are expecting to have bad weather that will isolate you from having modern devices that work, rent that generator or buy one as fast as you can...they go fast, very fast...

Here's another tip- if you have a land line telephone, check to see if you have voltage available on the wires. Remove the telephone jack, check yellow/black, and red/green with a meter to see what you have. Here at my house, I don't have a land line telephone, but I still have juice on the jacks. I have a 5, 6, 9, 12 volt regulators already put together with telephone plugs, so I can just plug into the existing jacks to get the voltage that I need.

If you have land lines, and you use red/green on the jacks- make sure you have a regulator, just in case a ring voltage comes down the lines. It can be a larger voltage, and if you are not aware of it- it will cause damage to devices if not handled right...

I used this 'trick' back in 1969 when hurricane Camilla hit the gulf with 210 mph winds. The telephone lines to my house still had voltage, I used it...

Yes, I'm that old....
floryzzz5 years ago
 NOW TURN IT ON (i mean the cooker)
nice thing
ReCreate6 years ago
is there anyway to achieve a perfect 5.0 volts using 1.2 v batteries and 1.5 ones?
a five volt regulator
It outputs 4.98V What a rip off XD
i think it will still work
Oh sure it will work, I figured that out about 3 months after i asked the question, I never knew about regulators before ;)
Ok, but some times you dont get ripped off. i once got a set of AA's. They each put out about 1.8Volts :)
Wow, 1.8?
yes, on a 1.5v battery
Weird...
You dont need perfect 5 volts, most devices are designed to be able to work with a little bit more or a little bit extra voltage
Yes but more than .8 of a volt could kill them, and less that .8 of a volt and they could malfunction...
That all depends on what you are working with, I am running three camera charger boards on 12V, they are designed to work with 1.5V.
You are overpowering a camera by 10+ Times? That is truly amazing, Show me a picture of the setup if it is true.
HELLO?
Last_Liberal (author)  ReCreate6 years ago
Doing the math, four 1.2v batteries would give you 4.8v, which *might* suffice, but my experience has been "just over is better than just under".

If you have access to 1.2v cells, I'd recommend three 1.2v batteries plus one 1.5v battery for a total of 5.1v. That's as close as you're going to get.
Thanks man it worked
4x 1.5 will be fine as said below.
Thanks
ahhh also with the rechargeable batteries i stick them in the fridge after charging them for me they last longer
flag them if they say something mean u are trying to help them dont take their rudeness and i meant to reword what i wrote but im buzy and lazy
Winegard RCDT09A they made that for portable tvs..................................
Flea6 years ago
You should take the words HD out of the instructable. Portable HD media players costs over $400 which I wouldn't consider low cost. You shoul replace it with LCD. Or change the title to "Low cost battery powered HD tuner". Otherwise, it's very misleading. I'd also recommend using rechargable batteries. They're 1.2V, so 6 rechargables would give you 7.2V. A little closer to the 6.5V used by the device. Plus, you'll save money on batteries and the environment :). All in all, a nifty idea.
Last_Liberal (author)  Flea6 years ago
Please note that my use of "HD" was responded to below. Only your choice of display affects the quality of the output. While I chose a portable DVD player, if you used an LCD monitor, you could get full HD (good luck powering it on batteries for more than a few minutes though).

On the use of rechargeable batteries, as my goal was to have a battery powered digital TV in a weather-related blackout following the February DTV switchover, one would be hard pressed to recharge NiCad's once the power went out... especially since NiCad's last about 1/3 as long per charge as alkaline batteries do.

While NiCad's may *start* with a higher charge, that charge *quickly* dissipates, and the receiver I chose fails to work without at least a steady 6.5v of power.

Thanks for the feedback and kind words.
NiCAD batteries are old technology. They do not store much power, but their discharge rate (as with NiMH) is much more stable than Alkalines. Below are graphs of NiCAD discharge rate and NiMH+Alkaline discharge rates. Rechargables provide a much more stable voltage. The main problem with rechargables is that they lose a signifigant amount of charge if you store them for long periods. Thankfully, this is the problem Sanyo's Eneloop battery solves (hey, they're sponsoring this contest, might as well promote them). Eneloops should retain about 80% of it's charge after a year of storage. They should also power your portable DTV for a longer period than Alkalines.
nicad_test.gifnimh_vs_alkaline.gifnewgraph.gif
Last_Liberal (author)  Last_Liberal6 years ago
(Since it appears to be an issue, I changed the title to "DTV" instead of "HDTV".)
your a genius!!!! now i might do this to doggie-t.v.
DanAdamKOF6 years ago
Pretty cool, but this isn't really HD if you're hooking it up through composite. Should still look pretty sharp though.
Last_Liberal (author)  DanAdamKOF6 years ago
Well, technically, it's only standard SD (480p) resolution, limited only by my choice of display. The tuner I chose is capable of full 1080i/p, so a higher rez screen can indeed do full HD. The DVD Player I used is capable of supporting true widescreen video, though the second Player I tried was not (yes, I checked the Player's settings), merely stretching the video, thinking it was on an ordinary 4:3 monitor. :(