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KeithLuneau

HongKong Video?

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I picked up one of the cheap "200mW" wireless cameras. It actually came with some specs on a sheet of paper that states 50mW output power. Anyway, I'm not too impressed with the range on it. It works great around the house on my r/c truck, but on my plane it's another story. It would be ok if not for the tuning knob having to be adjusted all through the flight. I read on the page about the frequency drifting because of a change in supply voltage. I'm powering the receiver with the wall-wart supply that came in the box, and the camera/tx with a 9V alkaline battery.

First, I would like to try powering the transmitter with a regulator, like is suggested on the project page. I need more info on that, like what IC to get, and a diagram with on how to wire it if possible.

Next, I'd like to experiment with better antennas. I'll try to scale up the ground plane antenna on the projects page for the receiver. The page for the camera says that the transmitter could also benefit from and upgraded antenna, but what kind, and where do i go to find out how to build it?

Thanks in advance for any and all info!

Keith

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First, I would like to try powering the transmitter with a regulator, like is suggested on the project page. I need more info on that, like what IC to get, and a diagram with on how to wire it if possible.

The LM2940T-9.0 is what you need. Just two caps complete the job. Wiring info is shown in the data sheet. Digi-Key has the link: http://www.digikey.com/scripts/DkSearch/dk...=293041&Site=US

The page for the camera says that the transmitter could also benefit from and upgraded antenna, but what kind, and where do i go to find out how to build it?

This should be last on your list to try. A 2.4Ghz groundplane is shown on yb2normal's site: http://www.yb2normal.com/antenna3.html. It can be scaled for other freqs.

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Thanks for the info on the regulator. I'll most likely try that first. This afternoon I set up the TV and VCR outside on a table next to my runway, and made another flight with the camera on my Slowstick so I could stay close in by the receiver. I used a fresh, brand new 9V alkaline, with hopes of the voltage staying put better than before. After I took off, I tuned the knob and it pretty much stayed set for the whole flight. THis time the video is actually not bad at all. The CMOS imager leaves a little to be desired, the colors are not that great, and it really hates the sun... lol onsidering what I have invested in the whole setup, I guess I'm happy with the results so far. Besides, it will give me something to tinker with until I can afford a real setup. :)

About that antenna, can I use a piece of plain old coax, and where should I solder the ground at on the transmitter? Could I solder straight to the PCB insted of using a connector? Am I right in thinking that once it's built and attached, I would point it straight down off the airplane?

I have alot of questions now, and will have more later I'm sure, I'm new to this part of the electronics scene.

Keith

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One more question, when I make the antenna for the transmitter, do I scale it the same as the receiver antenna on your website, say for 1.2GHz, I'd make everything twice as long?

EDIT - Ok, another question... (told you I'd have more... lol)

Do you think it would be safe to go with the LM2490T-10 (10V output) instead of the 9V version, in an attempt to get a stronger output from the transmitter? I see where you powered one with 12V and got more power, but I figure that 10 will give some gain and be a little more on the safe side.

I've scaveged through my electronics graveyard and found both the capacitors I need, now I just need to order the regulator and try it out.

Edited by KeithLuneau

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Ok, I've been tinkering with the camera some more. I decided to get rid of the heavy power plug that was on it. I carefully operated on it and removed the 5V regulator still attached to the wires. I was surprised to find what was some of the worse "professional" soldering I've seen yet. The SMT stuff all looked ok, but the soldering of the wires, and tot he metal part of the plug just looked terrible. In fact, The metal part of the plug just fell off in my hand. It looked like a cold joint. Anyway, with the solderin corrected, and now a longer lead and regular JST (aka BEC) connector, I was able to shed 11 grams off. That may not sound like alot, but the camera/tx with it's longer lead and new connector only weighs 13g, so I almost cut it in half. For the time being, I'll use a 7-cell 370mAh NiMH pack for power. I hope to try it out soom and see if that helps the range at all, having a better power source.

I also got a good look at the transmitter, and I'm not sure I could install a better antenna on it, it's all SMT, and really close together on the PCB. I'm not sure I could do it with the cheap iron I have here. I don't see where I would ground to anyway, there is just a single piece of wire for the antenna. I'll try GPP for the receiver, and build a 9 or 10 volt regulator as soon as I can get my hands on the components.

Wish me luck! :)

Keith

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Just a little update -

I have since built a GPP for this camera's receiver, and got a test flight. I was very pleased with it. I posted the whole story in the Antenna Problems and Solutions forum.

I also noted that using the NiMH battery on the camera, there was no need to adjust the tuning knob once it was set. It was fine without moving it for the entire flight. I only got one dropout, and that was while flying BEHIND the antenna! I'll probably just leave it as is with no regulator for now.

Keith

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I used a 9.6 volt park flyer pack on my hong kong camera and that worked very well. I've since moved up to a locked 2.4 ghz transmitter and I'm staying with that.

I think it's that the 9 volt transistor radio batteries just don't have the necessary reserve capacity to maintain optimal voltage and amperage.

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I was surprised to find what was some of the worse "professional" soldering I've seen yet.

A friend gave me a 1W HK TX to test because it didn't work. I opened it and found 10 missing soldering points. A full row of pins of the RF module was not soldered to the PCB... <_<

It worked very fine indeed after I corrected that little mistake... :P

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