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About Scratchbuilt

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    RC-Cam Visitor
  1. Hi guys, Still gathering and fabbing the parts to restore my 25 year-old scratchbuilt nitro .60 sized AP helicopter, Image III. Picked up a Nikon D200 with WiFi grip, 900 MHz downnlink and a KX151 camera already, an EyeTV Hybrid for the windowed analog live-shot on my MacBook Pro, etc. Also considering the newly-announced Panasonic HD camcorder model HDC SC5 using SD flash cards for the media. (or perhaps now I'll find a smoking deal on the SC1, though the newer SC5 version's having 8X faster sampling on the antishake gyros for optical stabilization might work better in a helicopter environment). Specs on camera seem nearly ideal, but for the downside having to open the twist-out LCD finder to access the composite out jack. Anyone here used one of the Panasonic HDC SC1 cameras? What was your hacksie or workaround for the video out? Ivan J. Eberle
  2. Thanks, guys. With Mr. R/C-Cam's confident assurance that this could indeed be done, I took out my smallest jeweler's screwdriver (looking under the 7X loupe a bit like an oversized crowbar) and gingerly slid all the pins out. These are really flea-sized pieces. Ended up soldering in a section of appropriate-gauge wire instead of trying to get a good connection by crimping at this scale, my smallest foreceps were much too big and I didn't feel like making up a microscopic die set just for the one crimp. Also stripped back the casing on the Composite lead to get at more than the one (!) strand of copper that originally comprised the negative lead. Thanks also for the tip about the thermoset glue gun, JMS-- picked up the littlest one of these yesterday at the crafts store along with what must be a hundred-year supply of glue sticks (barring a major global warming trend) for about $6. While I was doing this little project yesterday I was thinking how many of the cheap items these days need rework or updated firmware or even re-enigineered right out of the box--and that I always end up doing this stuff myself. And that I would often gladly spend a fair fraction more for more robust stuff. How frustrating this must all seem to non-DIY types.
  3. Hi guys, The availability of 900MHz equipment is so sketchy right now that I am not gonna whine too loudly about a defective cable for a SuperCircuits AVX900T4 transmitter that arrived just yesterday. Anybody have a part number and/or source for the itsy-bitsy 4 pin female connector at the transmitter end of the cable so that I can make up a decent new switching/charging harness? (Spiffy little transmitter but a crappy cable. Worked fine for a couple of hours until the neg lead slipped out of terminal because it was too many strands of shielding wrapped together, too fat for the terminal and poorly crimped. Discovered under loose heatshrink that only about 2 strands of the copper shielding on the Composite Video lead were left intact for the ground. Connector pins look to be soldered in situ and it seems likely I'd destroy the existing one to get the neg pin out to try to recrimp/solder it. Just easier to find a new connector, I'm hoping). Incidentally, as of last week Supercircuits was listing their 4ch 900 MHz FM receiver as discontinued, didn't even have any Tx/Rx/camera bundles in stock. Googling around I discovered the Marshall V-RC900-FVA4 is it's near twin. Ordered one through North American Video (877) 628-2283 though I found it/them online this URL http://www.cctvproducts.com/marvrc900fva.html for $108+ ship. Pictured as black but it arrived in identical beige (drop-shipped directly from Marshall Electronics it came through with generic markings like SC one). Fortunately also came programmed with a channel that worked with the SC transmitter. Heck if I know what actual frequency the channel is yet, absolutely no documentation came with either Tx or Rx. Ivan
  4. Apparently calling this Spread Spectrum is a bit of a stretch. Spread spectrum as I know it is frequency hopping, this is not, unfortunately. It's a pretty good implementation of a diversity system with a lock-out for in-use frequencies, but only upon startup... interference could easily swamp the signal and there's no hopping after the fact if it does...sigh. Too, from what I know of the signal propagation issues, 2.4 GHz is fussier and offers less range than 900 MH (also a license-free band). This might be a good scheme for a park flier, or in a congested area if everybody starts using their technology, perhaps? Don't know particularly why they'd choose 2.4GHz other than the chips are essentially WiFi chips and therefore ubiquitous and cheap. Anyhow, the Spektrum thing was an interesting diversion from my project for a time. But back to the drawing board. I've got a couple/three of these RS232/DB9 serial modems that can be configured for any number of data protocols. What I'm thinking is that I ought to be able to pretty simply use a servo controller board on the flight pack side, something like this: http://www.yostengineering.com/index.cgi?s...oCenterUSB.html and on the Transmitter side, utilize the USB simulator port with an adapter to DB9, bypass the RF portion of the transmitter with my spread spectrum link. Need to figure out the protocol of the signal as it comes out of the transmitter. I haven't got a modern radio yet-- do these use a standard USB cable or is there some black box involved as well? Anybody done any simulator work to know what the signal looks like, and offer an opinion as to the feasibility of what I'm attempting to do? -Ivan
  5. The receiver does look kinda wimpy, and that's only one concern, another being how robustly built it is, i.e. how well soldered (because all helis vibrate at certain flight attitudes, even silky-smooth ones like mine). Been following this 14 page Spektrum hacksie project this afternoon, maybe we can induce someone else to do the R&D recon on the servo amperage question: http://www.rcgroups.com/forums/showthread.php?t=458314
  6. Thanks for the links, guys, some interesting stuff. I'd run across Dave Jones's site some time back and noted that his FHSS Silvertone looks to be about the same vintage as my Kraft Series 79 and 80 sets, thus providing the inspiration for possibly hacking in my Freewaves if I could. Hey, come to think of it, even back then these radios were called DIGITAL proportional... though not sure if by "digital" they meant thumbs Truth be told, hacking Freewaves into a new heli radio myself without finding someone who's done a proof-of-concept on the circuitry ain't gonna happen, at least not for my control link (perhaps telemetry, but I'm thinking that 115.2kbps probably isn't enough bandwidth to fly a heli by an uncompressed video feed). I'm partial to the 900mHz band for it being less crowded hereabouts than 2.4gHz, and was really impressed with how robust these particular modems were as my internet end-link shot, even cheating by knife-edging over and around a mountain ridge 500 yds away. It's been a couple of years since we took them out of service, but from what I remember the latency only became a problem at the limits of reception, when whole (>1500 bit?) blocks of data would drop out and had to be resent. The block size is fully configurable in the modem setup menu, though more frequent error checksums would slow down throughput somewhat when the link was strong. Then again, how much bandwidth does even a 14ch R/C link requeire? (I'm thinking probably not very much, since most modeller-oriented radios are content using the 72mHz narrow-band regime). Googling around, it's apparent there are any number of folks using amateur R/C gear for business purposes. Used to be true that the FCC regs expressly prohibited commercial use of the amateur freqs. If that's still the case, this would seem to be a large incentive for development of commericial UAV radios using FHSS bands, and it's a bit surprising to me that there isn't much of a spread-spectrum module and receiver industry sprung up just yet. But it's looking hopeful, with stuff like Spektrum is developing. What sort of range are you seeing with your DX6 set, Mluvara? While I'm reasonably sure those teeny servos won't cut it on my 12lb .60 size heli, it's closest to what I'm looking for so far. Ivan
  7. Hi everybody, New to the RC-CAM forum, been away from the sport/obsession awhile. First got my feet wet with a Schluetter Heli-Boy back in 1979. Modded it as far as I could go and started over with a clean slate. Last flew my v.2.0 still-photo-purpose-built, industrial duty .60 glow-powered collective pitch heli in 1998, having built it in the winter of 82-83. Lately considering a full-on restoration lest it become a museum piece. "Image III" is still more modular and robust than any of the stacked frame jobs I see commercially available, if I do say so myself. One of the first orders of business. I'm about to spring for a modern PCM radio, I'm thinking. Original avionics was a old (top of the line back in the day) Kraft Series 80 7-channel radio, updated to later narrow-band 72mHz FCC frequency allocation--but of course it's so old as to be highly suspect, and just junking the NiCDs and re-celling might would cost nearly as much as a cheap modern radio with mixing (oh but what a joy electronic mixing and servo reversing will be, instead of mechanical mixers and bellcranks!) Also have a pair of 1W Freewave Technologies 900 MHz 115.2 kbps Frequency Hopping, Spread Spectrum serial modems to tinker with. While they don't have the bandwidth of WiFi or WiMax, they were fairly robust in a 27 mile point-to-point endlink (+10dB yagis on each end) which was my internet connection for a couple of years, since replaced by a satellite ISP (don't ask). Wondering if anyone here has attempted to integrate a Freewave modem pair for the control link? Have seen a number of the university UAV and autonomous heli competition projects that used Freewaves for telemetry links, what about for control? I'm sure I could get several miles LOS with dipoles, they're that good. While I can fly without any bells and whistles, I'm figuring I'll want as many channels as I can get for a camera ship, and that a FAI 3D pro radio with maximum channels is what I have in my sights. Autonomous capability with something like the CARVEC system is rather intrigueing, would like to keep my options open and keep everything compatible. I'm a few hundred miles N of Los Angeles, thinking of touring down to Ontario for the AMA Convention next week to get some hands on, solidify my thinking. In particular, can anyone point me to a resource that might help me integrate the Freewaves in place of Tx/Rx modules with a modern helicopter radio--hopefully with a minimum of pain ? Or a source for another pre-configured FHSS heli radio that would integrate with an auto-pilot and 3-axis rate sensors (spendy or otherwise) ? Thanks in advance, Ivan
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