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icharus

A couple questions about xcam2/RC-CAM4

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First of all, thanks so much for the excellent website - both this forum, and also the RC-CAM descriptions. They are very well done!

1. I just ordered "Xcam2 with audio" from this link for $89:

http://www.x10.com/products/x10_vk45a_av.htm

It says it includes a microphone within the xcam. So I was wondering why the RC-CAM4 page suggests a microphone addition. My guess is that the microphone offering is new, and was not available at the time of RC-CAM4. Right? I doublechecked their site and confirmed that "audio" does not just refer to the receiver capability -- it specifically says it contains a "microphone" in the Xcam2 (see the link).

2. The RC-CAM4 description has some discussion of antenna length, and how that might affect range. I am not an antenna guy, but in my business (cell phone) people routinely use connectors for a detachable antenna. I was wondering if anyone had implemented this. That way you could try multiple antennas without re-soldering. Re-soldering is not only a pain, but would possibly alter the situation each time, thus invalidating the experiment anyway.

3. I notice that the xcam2 page offers a battery pack - the description says it uses 4 AA batteries. Since RC-CAM4 describes needing 12v for xcam2 transmitter....I am wondering if : (1) this xcam2 battery pack contains voltage conversion to produce 12v, or; (2) the xcam2 design has been altered and now requires 6v instead (4x1.5v AA batteries).

I have not gotten the camera yet....maybe the answers to (1) and (3) above will be obvious on inspection/testing.

Again, thanks for the great website. We will try to contribute some videos and experiences (fixed-wing aircraft) when we get operational.

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So I was wondering why the RC-CAM4 page suggests a microphone addition.

Because when you replace the awful XCam CMOS camera with a decent CCD one, you lose the microphone feature.

I am not an antenna guy, but in my business (cell phone) people routinely use connectors for a detachable antenna.

You could install a SMA connector. The main issue is that, at microwave frequencies, small imperfections in your connector installations will gravely harm the signal. And connector choice must be made with care. They are best incorportaed only if you have experience with terminating microwave rated RF connectors.

I notice that the xcam2 page offers a battery pack - the description says it uses 4 AA batteries. 

This is an example of that gadget: http://www.rc-cam.com/forum/index.php?showtopic=352

I am wondering if : (1) this xcam2 battery pack contains voltage conversion to produce 12v, or; (2) the xcam2 design has been altered and now requires 6v instead (4x1.5v AA batteries).

The XCam battery adapter provides the necessary voltage conversion. The DC-DC convertor component used in XCam-4 does this too, but at a fraction of the size & weight. The NME0512S DC-DC convertor is fully described on the RC-Cam4 web page.

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Thanks for the info. FYI, the P9505ND is apparently discontinued at Digikey. It says "obsolete item, please call". Same for the P9504ND, which differs only by field of view (45 deg vs 53 deg).

I found it on Superciruits, but it seems to only be the 45deg variant. It mentions both, but seems to only have an "add this to cart" button for the 45 degree variant. I don't suppose it matters much, but I think the slightly wider view would be better.

I might try an SMA connector - I work with a bunch of cell phone antenna guys, so I will ask one of them for pointers and see what they say. They design phones all day long, so if anyone would know how to do it, they should (On a cell phone, an SMA connector is generally required at least for RF parametric testing for operator approval --which is done cabled, not radiated. The PCS band is around 2GHz, so it is probably similar).

Edited by icharus

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Yes, the CX161 is discontinued. The RC-CAM4 project came out long ago and parts are slowly going obsolete.

You can get the camera from blackwidowav.com and rock2000.com. A very low cost variant, that works great, is this one: http://www.rc-cam.com/forum/index.php?showtopic=384

Be sure to order the mating cable too.

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I am making an RC-CAM4, and got to the point of hooking up the battery. I checked the voltage first, and was surprised to find that my "4.8v NiMH" battery is outputting 5.8v. I can clearly see there are 4 cells, and in fact it says "4.8v 600mAh" right on the pack (it comes from a Hobbyzone Firebird 2). But my voltmeter says 5.8v.

I am afraid to connect it to my $100 Panasonic camera, since it exceeds the recommended maximum of 5.4v. I am going to do some research on the web, but do you happen to know why I would be seeing such a high voltage? Should I get a NiCd pack instead?

Thanks again for the guidance so far.

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OK, I think I found an explanation. The link

http://data.energizer.com/batteryinfo/appl...tal_hydride.htm

gives an excellent tutorial on NiMH and NiCd batteries. I think the problem is my battery is fully charged. According to the data given there, the peak voltage can be about 1.4v per cell, or 5.6v for this pack. This quickly drops to about 1.2v as the battery discharges a bit. So that peak is close to what I am seeing.

I guess my question at this point is....in your experience have you had any problem with hooking a fully-charged NiMH cell to your camera? It appears that it does exceed the maximum recommended voltage for the Panasonic camera for a short time, until the battery loses the first few percent of its charge.

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The concern is real since voltages higher than 5.5VDC can harm the camera. But, I have yet to hear of anyone damaging the panasonic camera using a 4-cell NiMH or NiCD pack. I have successfully used the 4-cell method on several cameras and others have too.

I rely on the voltage sage that occurs under load. I use 720mAH AAA NiMH cells, so they drop a lot under the X10/camera load.

Keep in mind that an unloaded fully charged pack will have a high voltage on it (up to 1.6/cell). But that is not a fair test. Load it with 250mA and then see what you get.

If you want to play it safe then you will need to use a higher voltage and then regulate it down to 5.0VDC.

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1. Good point on the IR drop - I had forgotten about that. I tried to test it with a 22 ohm resistor to produce ~250ma load (after all, I can't hook it up to the camera to test if it will blow the camera!), but unfortunately I picked out a standard small resistor without really thinking about the power (250ma*5v). I think the small resistors are 1/4 watt, right? Anyway, it burned up before I could get a good measure.

I ended up just hooking the battery to my plane and running it about 15 seconds. That was enough to lower the voltage to a safe one, even unloaded, and didn't take away much capacity. Good enough for a first flight.

2. I ended up going to an OSX connector. My soldering is not as good as yours - I couldn't fit the whole mess back into the X10 transmitter's plastic case. So I bought a project box from Radio Shack, which can hold both the Tx and the battery. The OSX female is superglued into the side of the plastic box, towards the bottom. So I can rotate the antenna to point either back or down, just by rotating it around the female OSX.

A friend of mine matched the antenna to 50 ohms using a network analyzer and a couple very small components (0402) on the back of the female OSX. We ended up getting what seems to me much more than 100 feet of range.

We took a test video last week (with the camera attached to an Aerobird Extreme using just electrical tape), I'll post when I get a chance to load it on the PC, then you can judge the range yourself. The plane flew surprisingly well given the weight.

Anyway, thanks again for the site and the tips...we pretty much finished except my amplified mic didn't arrive yet.

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