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Pixelcam Mod for Baseband Video Output


Photo by: Kevin Triplett

PixelCam or Pixel Vision Camera

(Photos and instructions courtesy of James Bodard, Jesse Chenven, Andrew Sempere, and Kevin Triplett.)

The Fisher-Price PXL2000 has taken microcinema by quiet storm (to skin a metaphore). Pixelcam shots can also be found in music videos and feature films (Michael Almereyda's epic Another Girl Another Planet was shot entirely in Pixelcam and scenes in his Hamlet and Richard Linklater's Slackers were shot with a similarly modified Pixelcam.

In it's pristine form, the camera records both moving images and sound onto high-bias audio cassette tapes. It's okay but you have to use the RF amplifier to get it into a computer or VCR plus the quality of tape and what temperature it was shot at versus what you're playing back at can make a noticable difference in terms of noise (little glitches appearing at random places on random frames).

The best way to use the camera is record onto videotape. It can be VHS, 8mm, miniDV, heck ... even digibeta. The best signal you can get is ''baseband'' video, similar to what camcorders output and what VCRs take as input. Which is nice because this signal can be connected to the input of a VCR or a camcorder that can record video when in VCR mode. If your VCR or camcorder has separate inputs for video and audio, then most likely it will work with these modifications (assuming your camcorder can record video ... some can't). This modification WILL NOT work with VCRs that only have a screw-on connector for both video and audio (mainly used with an antenna or cable TV connection).

At Mopac Media, we route our PixelCam video into a miniDV deck for recording. It's overkill but we can then import the images into our computer over firewire and not worry about degrading the images any further (ironically a big concern given Pixelcam low resolution). Plus, our Sony GVD-900 miniDV deck is compact, portable, and easily carried by the camera operator.

The only problem with the modifications that are published elsewhere on the Internet, the signal tap inside the Pixelcam cannot drive a 75 ohm video input, which is typical of many decks and televisions/monitors. You might be able to find a deck that the camera can drive, but most of the time you'll have to add the small buffer amp inside the camera that's described here. Our simple buffer that can be housed inside the camera and is easy to build, provided you (or a good friend) is handy with a soldering iron.

NEW! User Jesse Chenven has reported success in creating an external buffer amplifier (see below). This solves a problem with the internal buffer amp: while it works great, it messes up the standard RF-modulated video output. So you can't have it both ways, both TV audio/video and baseband audio/video unless you build Jesse's version of the buffer amp. It's the same buffer amp, just built to be external. See the following pages for a description of his clever solution.

Follow the steps 1 through 3 to tap into the video and audio signals in the camera. Then constuct the buffer circuit and complete the modifications with steps 4 and 5. I prefer to drill holes in the camera case but that may decrease the resale value of your camera, for collectors who aren't using the camera for filmmaking. I then attach RCA jacks through holes. But there are other ways to do it (you'll see what I mean when you get to step 5). Enjoy!

CAUTION!

I certainly don't want to scare you into not modifying your camera but there is one important thing you need to be aware of, namely that the Fisher-Price PXL2000 was designed in the early 1980's when electronic circuits were far more prone to damage from static electricity than they are today. ALWAYS use caution when you open your PXL2000 and make sure you discharge any static electricity from your body before touching the circuit boards inside the camera or YOU WILL destroy your camera. Since the chips inside the camera are no longer available, I'm afraid that once you damage the circuits, the camera is useful only as a coffee cup holder or as a conversation starter at parties. Email me if you have questions about this. I AM NOT RESPONSIBLE FOR DAMAGE TO YOUR CAMERA. ;-) That said, it's fairly straightforward to modify your camera, just take care about static electricity.

STEP 1: Removing the Cover

Here's where you get to feel like a surgeon -- opening the case of the PXL2000 is accomplished by unscrewing all seven, count 'em, seven screws that hold the camera body together. These screws are on the side OPPOSITE the tape door (as shown). If they haven't been pried off before, you may need to pry off the four rubber pads that are in the middle of the camera body -- this gives you access to four of the screws, which are cleverly hidden.

Once all these screws have been removed, take off the battery doors and gently pull the camera housing apart. You may need to unpeel the battery stickers that show you which way to put the batteries in (just unpeel one side!). Take your time and care to kind of wiggle the cassette mechanism loose. Your camera should now appear as it does in the picture below. The area inside the orange square is of primary interest - the next few steps will be performed there.

STEP 2: Exposing the Source

In order to get at the hot spots where you tap into the audio and video signals, you have to get under the large metal plate that you see in the following photo. This is easily done by heating up the tabs with a soldering iron (the upper tool in the photo) that secure it to the circuit board and gently prying it with a screwdriver (the lower tool in the photo) at each tab where you melt the solder, until all of the tabs are free.

By the way, you do NOT want to break off any of the tabs on this big metal piece, trust me. If you do, all is not lost, you can fabricate new tabs with wire or solder wick.

Once all the tabs are free, swing the plate back (again, carefully, you don't want to break it) without breaking it (as shown in the bottom image -- this is how it should look, not all mangled).

STEP 3: Constructing the Buffer Amplifier

You need to take a trip to Fry's, Radio Shack or your area's Surplus Electronics Shop and pick up the following parts:

Bill Of Materials
Qty Description
1 2N3904 NPN bipolar transistor
1 100 ohm 1/4W resistor, 10% tolerance or better
1 10K ohm 1/4W resistor, 10% tolerance or better
1 47K ohm 1/4W resistor, 10% tolerance or better
1 220 pF (picofarad) ceramic capacitor
(be careful not to break the fragile ceramic around its legs)
1 10 uF (microfarad) non-polarized electrolytic capacitor
(can be polarized, see below)
2 RCA phono jacks
(chassis-mount type for soldered connections)
small
spool
Solid-conductor hookup wire
(or as we like to say in East Texas, ''hookup war'').
Optionally, you can get various colors to make it easier to follow.
optional Small perforated circuit board.

Here's the schematic for the buffer amp ... this is what you're going to build. If you want to skip this step and try out Andrew Sempere's original design (you're free to come back and build the buffer amp if it doesn't work out), you can skip to step 4.

You can construct this buffer amp on a perforated board, printed circuit board, or use point-to-point wiring as shown in the following photo from James Bodard. NOTE: The pins for the transistor may vary, so please use the pin out for the transistor you are using and not what's shown in the photo. Even so, don't worry ... if you get the pin out wrong on the transistor, as long as the rest of the circuit is correct there's little chance you will damage your camera ... your buffer just won't work.

If you look closely at the above photo, you'll notice that James used a polarized capacitor. This is okay, I chose a non-polarized capacitor because I didn't know the bias voltages for every Pixelcam out there, not having the schematics to go by. But the polarized capacitor should work fine, just connect the positive side to the base of the transistor and the negative side to the video connection on the camera circuit board (see next step).

STEP 3: Soldering the Signal Lines

Now that you have access to the hot spots (the baseband audio and video signals) we can solder a wire to each point. Be careful to solder only to one point and not to leave too much exposed wire or you may have a problem later on.

Here's the original photo, if you want to first try Andrew's original approach (without the buffer amplifier).

Also, keep track of which wire is audio and which is video. This is mostly for your convenience - it will be difficult to tell once the metal plate is replaced. I recommend either sticking a little sticker on the video wire, marking the video wire with a pen, or just tying a loose knot in the video wire. (You can do any these of these tricks with the audio wire too, I just decided to pick on the video wire.)

STEP 4: Finishing up and Testing

Upper photo and instructions courtesy of James Bodard, middle photos and instructions courtesy of Andrew Sempere, and lower photo courtesy Jesse Chenven.

To route the wires, it helps to knock out the rib at the rear of the camera. This rib makes the camera body more rigid and less prone to damage, but as long as you don't drop the camera or get mad and smash it against a wall, you won't notice any difference or have a less-sturdy camera for everyday wear and tear.

Andrew's original instructions, for those doing without the buffer amplifier:
(Note: even so, these instructions may be useful for those of you using the buffer amplifier.)

At this point you should have two wires securely attached to the proper points on the circuit board. Now bend the metal plate back into place and re-solder it (a reverse of step 2).

Finally, both the audio and video jacks are going to need a ground. For this, solder two wires to the metal plate. It doesn't matter which wire goes where, just as long as they're both attached to the plate somewhere, see photo below.

The strange-looking gray thing with the four plugs? That's Andrew's power adapter, a universal device that can supply power to any number of devices, pretty handy to have. You can get one at most electronics supply stores.

Now pair up the to fo wire and one of the ground wires and attach them to the proper points on one audio plug. Do the same for the video wire.

To test, just hook up the video cable to a TV and try it out. You don't have to have tape rolling to output video but you DO have to push in the record-play buttons. That means, you need a tape in the camera (and one that does not have the write protect tab broken out). You can test the audio the same way, but be ready for feedback (turn the volume down on the TV until it stops whistling.

If the video is distorted in anyway, and you didn't build a buffer amp, you may need to build that buffer amp. :-) Be sure to check out Jesse Chenven's external buffer amp below before you crack open your Pixalcam case again.

Screw the case back together and you have the camera back the way it was, except now you have video and audio out! Oh ... before you screw the case on, if you're FEELING ADVENTUROUS, you can remove the IR blue filter from in front of the CCD array. This will give you a little more light sensitivity BUT it is difficult to explain how to do this and requires that you refocus the lens. If you're mechanically inclined, it's pretty straightforward, but beyond the scope of this article.


External Buffer Amp by

Jesse contributed a solution to the problem that with the internal buffer amp, you can't use the RF-modulated video output (at least he couldn't, YMMV). Here's his report: ''When the buffer amp is installed, the original RF signal becomes slightly distorted with slight horizontal scan lines.'' His solution was to build the buffer amp externally and power it with a separate 9V battery. This has the added convenience of not having to build multiple buffer amps for multiple cameras. It also means that if you want Jesse or me to build the buffer amp while you tap into the video out of the camera, you don't have to send us your camera.

Just build the original modification with only the RCA connector connected to the video and audio outs on the camera circuit board, don't add the buffer amp. Then build the buffer amp externally (Jesse cleverly used an old tic-tac box) and away you go.

Here's Jesse's report on the external buffer amp: ''I built the external amp and it worked. As you can see in the photo it is housed in an old tic-tac box. The key was connecting all the grounds (amp, input, output, battery) to each other. The best way to use it is to tape on the 9V battery so that it is all one unit. Then the [battery connector] can be taken on or off each time you use it (important because otherwise you will drain the battery). Although it is a little bulky to carry around, it would mean you build one amp for many cameras. Plus, it avoids my original problem with the interference to the RF signal.''

''Also, as bit of irony to the whole thing, now that I use the external amp, there is very little interference. Perhaps because of the distance?'' [Could also be because of the external battery powering the circuit. I originally suspected the load of the buffer amp was somehow messing up the RF signal but apparently that is not the case.]


JESSE CHENVEN'S EXTERNAL BUFFER AMP -- A CLEVER USE FOR A RECYCLED TIC-TAC BOX


Additional notes and instructions from Andrew Sempere's original site:

Finishing up and testing

Once all the above steps have been followed, you should have something resembling the image below. Run RCA cables from your newly soldered jacks to the input of a TV or VCR and attach the power supply. With everything in place, press the record/play buttons and pause the tape unit as you would if you were filming normally - the video and audio should appear on your monitor. Congratulations! Your modification was successful! Now put the camera housing back together and go shoot something. (NOTE: If you do NOT see or hear anything, double check that the TV is on the right channel, etc. If you still don't see anything, go back and review each step carefully to see if you did anything wrong.)

Construction Notes

At the right you see a picture of Mark Bennett's completed modification. He has this to say about it: ''I thought it would be best to have both female jacks coming out of either side of the plastic case. Unfortunately while the top side worked, the back side didn't have enough space to accommodate the mount on the inside... In the end I removed the female RCA jack and had the two leads dangling out the back of the camera. Will find some sort of covering/restrainers for the holes one day soon.''

Andrew Sempere has this to say about his camera: ''I chose to gut the inside of my camera and remove the tape transport unit and the microphone. I also used a smaller RCA jack that was designed to screw flush and leave only a very small amount of the jack on the inside of the housing. The result is a very light camera with one jack integrated into the camera housing. This is probably a more drastic mod than most will want to make, but I'm pretty sure that if you can find these smaller RCA jacks you can fit both of them in the camera housing itself.''

The other option is not to drill holes at all - just remove the pause button and run the wires out of that.

Created: 2005-04-04
Modified: 2005-10-13

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