Wireless "Flight" Camera Question

The current draw is really irrelevant as long as it is above what the receiver needs to operate. If the receiver draws 300ma and you have a 20 Amp power supply, the recover will only draw what it needs. Just make sure the voltage is within its specs or it will probably sprout a chimney if its to high.

| I have tested this set-up around the house, and the quality is pretty | good - however, how do you guys hook up your receivers outdoors? | | I suspect most come with a 12V power adaptor like mine does.

So use a 12 volt gel-cell battery. Small ones for use in field boxes and the like can be had for around $20, and they'd probably power it for hours. Possibly days.

| I have everything set up for a "true" wireless camera system, but the | problem is powering the receiver.

Odd. That's usually the easiest part :)

| Has anyone with a similar set-up been able to power their receiver with | a 9V battery? My receiver does say 9-12V next to the power input socket

Then it would probably work. But 9v batteries are very expensive compared to the power they generate. Don't power it with a 9v battery. Get a 12v gel cell battery, or a 9-10 cell AA pack.

(Actually, if it works on 9 volts, an 8 cell AA pack ought to work just fine.)

Personally, I wouldn't even power the transmitter with a 9v battery. I'd either use the plane's battery, or a small 3 cell LiPo pack, maybe with a 9v voltage regulator. Keeping it light is important, and 9v batteries are sort of heavy.

| although no mention of current is given (may be 500ma if it is the same | as the one above, except mine also transmits audio).

What seems more likely is that the transformer they have is rated at

I built a Video box to carry all my video ground support equipment. It is a plastic tool box with wheels that I purchased from OSH for about $30. Big bottom compartment where I installed a Die Hard lawn tractor battery. Center compartment holds the various rxs and a small 12v BW TV. Tray carries the various leads, connectors, etc. I have a tripod that supports the pvc mast or I just bungee the mast to the box.

Thanks for the input.

Eventually, I will be powering the tx via the heli.

I have ordered a few 9v batteries for cheap and will run a few tests.

Do you have a multimeter with an amps setting? Just put it in series with the power supply and you'll soon find out how power you need - same with the transmitter. As others have mentioned, a 12v gel cell is the simplest solution for the RX end.

To have any kind of range, the transmitter needs to be reasonably powerful - around the 50-100mW mark - that kind of output will draw considerable current - I'd be guessing anywhere from 200 to 500mA depending on the transmitter voltage, design and output. There's no way a little 9v battery will power that kind of transmitter for very long. I'd consider making up a pack of AAA NiMH cells.

I use a 9V Duracell drycell battery for both the camera/xmtr and the ground rcvr and it will last for several flights when the camera/xmtr is strapped to a heli.

The biggest problem is not the power source (any battery combination giving a 9V source will likely work very well), but is the highly directional nature of the rcvr antenna. Flying a regular circuit (race track pattern) the xmtr signal will be lost in several places. Having an assistant moving the rcvr as the heli moves helps some, but the assistant cannot anticipate every signal loss. Hence, never a smooth video sequence.

Here is some info that I was given some time ago. Naturally, I never got around to making the improved antenna system....

Email from me -

H i -

I looked at the videos on your web site. Most impressive. I've been playing with a unit on my helicopter and find that it is highly directional. Good pix when the heli is pointing in just the right direction. Your site mentioned something about a "antenna disk" . My antenna is a short piece of wire about 6" long. Where do you come by these antenna disks and is the use process as simple as soldering the existing wire onto this disk?

TIA for whatever info you can provide.

The response -

Hi. Thanks! Still works in progress but I am getting there. As far as patch antennas, that would depend on what frequency band you are operating on. What I am using for the USBW videos is a 2.4ghz patch antenna I purchased from BlackwidowAV.com. I also have one I won on Ebay that is for the 900mhz band to use on my Kadet Senior. For the 1.2ghz Hongkong systems you would need to fabricate a patch antenna yourself. I havent seen any for sale anywhere that I have looked. There are detailed instructions on how to do this on MR RC-Cam's website. His instructions are for a 2.4ghz patch antenna but you simply double ALL the dimensions for a 1.2ghz antenna. The antennas I am using all have the connectors that match what is on the receiver. The antenna that is on the transmitter is whatever came with it, whether a screw on type or a wire coming out of the housing. Any more questions, feel free to ask and I will help if I can. This is all a learning process for me also so a lot of the technical stuff is still over my head!

Dan

| The biggest problem is not the power source (any battery combination giving | a 9V source will likely work very well), but is the highly directional | nature of the rcvr antenna.

If the antenna is just a straight piece of wire, it's not very directional. Yes, it does have some gain in certain directions (mostly perpindicular to the antenna) but it's quite moderate -- 3 dBi or so.

The transmitter antenna is probably directional in a similar manner, but of course that's harder to aim in a reasonable way.

The real problem is that the power and range is already very marginal, and so it doesn't take much of a reduction to make it stop working.

As long as your receiver antenna points straight up and you're not flying directly overhead, the gain should be in the right general direction. (In general, as the angle to the helicopter gets higher, the gain will go down, but you're also likely to be closer, so it may be OK.)

As for how to improve it, perhaps a longwire antenna? Remove the stock antenna, and make a new one with a new connector with a several foot (or more) wire or so on the center connector, and ground the other connector with a wire and a stake that you stick in the ground.

Or perhaps _two_ straight wires, both of the appropriate length, connected at the base of the antenna, at approximately right angles to each other? Or three, all at right angles to each other -- that would come reasonably close to an isotropic antenna, one with no gain at all.

(About the `appropriate length' -- it's 234 inches/the frequency in MHz. So for 1.2 GHz it's 2.34 inches. You can also multiply that by an odd positive integer -- so multiplying by 3, 5, 7 etc. would be OK, and it might even work better. The more exact you are, the better it is likely to work.)

Antenna design is indeed a precise science, but with all the variables involved, it turns into more of an art. You may need to try a lot of different things to find the best solution.

Note that most `improved' antennas are improved by having lots of gain, which is exactly what you don't want. Gain is good if your antenna can be pointed in the right direction, but that's not the case here. You want low gain.

| Do you have a multimeter with an amps setting? Just put it in series with | the power supply and you'll soon find out how power you need - same with the | transmitter.

Good advice.

| To have any kind of range, the transmitter needs to be reasonably | powerful - around the 50-100mW mark - that kind of output will draw | considerable current - I'd be guessing anywhere from 200 to 500mA | depending on the transmitter voltage, design and output.

(Though I don't know how much power the CCD camera itself uses. Measuring it yourself is the best plan.)

| There's no way a little 9v battery will power that kind of | transmitter for very long.

Nope.

Apparantly the `really high capacity' 9v alkaline cells are rated at around 600 mAh, and that goes way down when they're discharged at over C/5 or so. (The 9v NiMH batteries are usually less than 300 mAh. But they do handle higher discharge rates better.)

| I'd consider making up a pack of AAA NiMH | cells.

Definately. Cheaper, and will last longer.

My son carries the works in a gun case. Sets the ant. on a tripod and every thing else is contained in the case. He is using a gelcell from an old battery backup to power the receiver system. Transmitter is powered by a 3s2p lipo and a stepdown resister to provide the voltage to camea and transmitter. Works better than taking power from the airborn pack.