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About mike_s

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    RC-Cam Visitor
  1. http://myauntishot.com/2009/full-scale-air...and-helicopters So I had my basic idea down. iPhone joins the Linksys router network. It gets an IP address. Then, I open up my pilot program. The pilot program interfaces with the router via SSH (I couldn’t think of a better way that has redundancy, and speed, and was already buily by someone else). The pilot program interprets what the iphone is doing, and outputs data to one of the ethernet ports of which there are conveniently 4. Rudder, Ailerons, Throttle, Elevator. Finally, you may ask how the servos are being driven. Well, routers are used to send bits of information down a series of twisted pair wires usually. Guess what it takes to send packeted information? An IC that would work really well as a PWM! I did some haxoring around on this, and read what other nerds had done on the internet, and the next think you know I have a servo with a Cat5E plug on the end of it. There seems to be some "speculation" on whether this is actually doable http://www.helifreak.com/showthread.php?p=...759#post1287759 http://www.rcgroups.com/forums/showthread.php?t=1043150 http://runryder.com/helicopter/t512044p1/ I'm curious (along with others) on the ethernet -> PWM -> servo interfacing. What is required for the hardware / software to control multiple servo channels over ethernet? The pilot program interprets what the iphone is doing, and outputs data to one of the ethernet ports of which there are conveniently 4. Rudder, Ailerons, Throttle, Elevator. I don't see how seperate ports on the router is of any use, unless there is a seperate i.p. address / network card attached to each servo ? Mike
  2. After failing to get the Q&D "antenna interface" [url=http://www.rc-cam.com/forum/index.php?showtopic=2718] working, I'm starting to try to design /research the basics of a 72.990 receiver front end /interface for my Futaba T6xAs to connect to the soundcard (mic or linein) inputs for use with a software oscillocope So far, I've found information on calculating the values for a resonant circuit, and have wound a coil and put a trim cap on a breadboard. For the coil I wound 12 turns of #26, which should be ~ 1uh according to this calculator I have a 2-30 pf trimcap. So I guess the next thing would be ~70mhz capable amplifier, to bring the signal up to ~1v for the soundcard? If so, I can probably find a circuit for it using an LM386, 2904 or 741, all of which I have, but if someone already has such a circuit, I'd love to see it. Assuming I'm on the right track, I think I'd need a cap (preferably for ease of construction) or a transformer to connect the coil/trim cap tank-circuit output to the amplifier input ? ... Or can I connect the "tank" directly to the amplifier input? ... Ok, I have no idea how to connect the tank to the amp, info /answers greatly appreciated. Also, a simple antenna would probably help , ~3 feet of #26 wire or some such ? What would I need to connect that to the "tank circuit"? Ok, with those two components connected,, a first step would be to have an LED blink in response to the received signal. What resistance / other components would I need to connect the amp output to the LED? (I know I need at least a current limiting resistor for the LED, but I don't know what is required to "generally" connect (if there is such a thing) to the output of the amp. Assuming that all works, at ~72 mHZ, the LED probably won't blink but will just stay on I'd guess . A "side project" would be frequency convert the amp output down to something visible, but that's a second priority. (Feel free to post info though if you're interested Now to the soundcard. I think I have to limit the voltage (current ?) output from the amp to soundcard. Is a two resistor voltage divider => ~1volt output sufficient? If I can get all this working, the next step will be start demodulating / decoding the signals. A whole 'nother project in itself. thx in advance for any info / tips. Mike
  3. "The frequency range depends on the sound card, but 20-20000Hz should be possible with all modern cards. " Ok, 79.90 mhz is a "bit" higher than 20K , but wouldn't the signal show up as "aliased" ? (Possibly on a "real" scope, rather than soundcard/sofware one ....if there is a difference. If not, then if transmitter freq was ~15 - 20K, would anything be conducted? I.e. is it possible to directly connect to the antenna? Mike
  4. Greetings, As will become obvious as you read this post, I'm a beginner with electronics. I've done some simple experiments with breadboards, TTL IC's, passive components, and I know some of the very basics about d.c. and a.c. theory, but even a fairly simple circuit / principle can quickly get me "dazed and confused." I have a Futaba T6xAs transmitter and I am interested in viewing the transmitted waveforms on a p.c/soundcard oscilloscope. Actually, I'm interested in viewing the output of other circuits that I want to build as well, but I thought I'd start with something already built and working This is the software I'm using : http://www.zeitnitz.de/Christian/Scope/Scope_en.html The software is working with a mic plugged in to the soundcard, or with a sound source into the line in port. Ok, so don't laugh too hard, but I naively tried hooking the antenna directly to the mic input (not really expecting it to work), by wrapping two wires around the tip and center conductors of "guitar" cord type connector, then wrapping the "tip wire" around the antenna. I tried putting the "center wire" on the (external) base of the transmitter antenna, and then tried "grounding" it against one of the metal parts of the face of the radio. Neither worked. I also tried just plugging headphones into the mic jack of the soundcard, and holding the leads of the headphones near the transmitter antenna, thinking that the headphone leads might act as an antenna So I have a few guesses on why it doesn't work. Please confirm / refute / ridicule / expand on my ideas. 1) Antennas transmit through air / space / vacum, not by direct contact Any "direct" connect is doomed to fail. 2) A "direct" connection IS possible, but something a bit more sophisticated than a bare cable touching the antenna is required. If so, what would be required? 2a) I assume the (literally) micro / nano ? voltages generated by an antenna can quickly be "killed" by a crude hookup like I was attempting. Any tips, links greatly appreciated. I have the ARRL handbook, and I've been googling antennas, soundcards, impdance matching and everything else I can think of, but I can't find specific answers as I assume that the answer is contained from knowing how all those (and others) principles interact. Mike P.S. I'm starting to try and build an antenna / interface / amplifier / receiver, that might even work , I will start a separate thread on questions about that project. So far, I've found information on calculating the values for a resonant circuit, and have wound a coil and put a trim cap on a breadboard.
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