28 the aerial eye / winter 1997 the aerial eye a quarterly publication of the aerial photography committee of the American Kitefliers Association volume 3 / number 1 / winter 1997
US$4.00 USA & CANADA
US$5.50 overseas
Villas, Porto Rotundo, Sardinia, by Patrick Morin. Nikon 2000, 4m delta.
P.C. Electronics sources 2522 Paxson Lane If you can’t find what you’re Arcadia, CA 91007 looking for locally, try these: Phone (818) 447-4565 Amateur TV equipment. Catalog. Supercircuits One Supercircuits Plaza North County Radio Leander, TX 78641 PO Box 53 Phone (800) 335-9777 Wykagyl Station (512) 260-0333 New Rochelle, NY 10804 Fax (512) 260-0444 Phone: (914) 235-6611 Extensive selection of micro- ATV Equipment. Catalog. video equipment. Catalog. Tower Hobbies Eglise de la Digi-Key Corporation Post Office Box 9078 Trinité, Cherbourg, 701 Brooks Avenue South Champaign, IL 61826-9078 by Thief River Falls, MN 56701-2757 Phone (800) 637-4989 Christian Phone (800) 344-4539 (217) 398-3636 Becot Web: http://www.digikey.com Fax (217) 356-6608 Wide selection of electronic Radio Control and model-making components. Catalog. equipment & supplies. Catalog. KAP ELECTRONICS 2 the aerial eye winter 1997 3
our feature this issue: the aerial eye send us that stuff! As we start our third year of publica- KAP electronics This newsletter is produced by the Aeri- tion, interest in KAP continues to spread al Photography Committee of the Ameri- by STEVE EISENHAUER worldwide. We’ve added another dozen can Kitefliers Association. It is our goal to new readers since last issue. On the oth- publish quarterly, in August, November, I know a little about electricity, and less read about video- February, and May. er hand, as we expected, we lost a few at about electronics. My cradle’s wiring con- aiming, a walkie- the end of year 2. But this issue will still nections are all soldered, my ni-cad batter- talkie used to release Single copies and subscriptions be mailed to 160 or so. (including back issues) are available to ies are fully discharged before recharging, the camera shutter, AKA members and non-members alike, Half a dozen new contributors have spare AA lithium batteries are in my came- modifying a transmit- under the following fee schedule: jumped in for this issue, and if you’re still ra bag in case the ni-cads fail in cold weath- ter so it can be worn single 4 issues procrastinating, we’d love to hear from er, one mini-servo trips the camera's shut- on your belt, electric AKA $3.00 $10.00 you too. Deadline is the first of the ter and another servo rotates it 360 shutter releases, ro- overseas $4.50 $16.00 month of publication (see left). degrees. Nothing I’m doing is electronical- tary switches,and sev- ly ingenious. eral ways to improve Non-AKA $4.00 $15.00 Text via Email or on 3.5" (9cm) high- I did alter a servo once so it could turn on standard R/C ser- overseas $5.50 $21.00 density disk (Mac or IBM in ASCII text for- vos. mat) is preferred, but typed text or hand- 360 degrees continuously. With a 12-tooth Domestic subscriptions will be mailed In reading about electronics in this issue written letters are welcome too. Like- gear on the servo shaft and a 4-tooth gear by first class mail; overseas subscriptions of AE, I feel a great sense of relief. When wise, diagrams in PICT, EPS, or TIFF on the cradle's pendulum shaft, the servo (i.e., outside North America) will be mailed would then rotate (pan) the camera slowly our fledgling committee initiated AE in Sep- formats are best, but pen drawings, pref- by air. in either direction. By sending my S-VHS tember, 1994, we had to include too much erably on white paper, will work as well. Advertising is available in modules of video camera aloft in this cradle, I could ap- of our own writing and photography But 2.25 inches wide by 1.25 inches high, at Photos may be sent as negatives, proximate the view of a hawk in flight our goal for AE was for it to become an $20.00 per module, payable in advance. prints or slides, or by electronic transfer— looking slowly one way then the other open forum for ideas and information, not Advertising in which aggressively most of the time. We can also read Ko- then circling around. But this alteration a podium just for our personal thoughts. competitive pricing is featured will not be dak PhotoCD, or 3.5" high-density disks in was more mechanical (cutting out the tiny We hoped to help crew a ship full of inter- accepted; call if you have questions or the formats listed above. We'll keep the stops and one shaft nub from inside the esting and expanding personalities on a need more info. Camera-ready copy is not prints unless you direct otherwise, but re- servo) than electrical. voyage of discovery about kite aerial pho- necessary, but is acceptable if it meets turn all negatives, disks, CDs, and slides— The articles and letters in this issue of AE tography. the above criteria. Copy deadline is the eventually. put my limited knowledge to shame. I now sense that the AE ship is under full first of the month of publication. Contact Send everything to Brooks Leffler at You'll hear from KAPers, many of them sail, the crew is motivated and capable, the Brooks Leffler. the address below. new to these pages, in Canada, Great Brit- passengers are supportive, and the wind is ain, The Netherlands, Germany, and France, blowing consistently between 5 and 15 as well as several from the USA. You'll mph. • æ american kitefliers association aerial photography committee under 1/15th second,” says Christian. He Steve Eisenhauer, Chair Brooks Leffler, Editor about the cover adds, “I framed with video, but it was not 229 Lake Ave, Pitman, NJ 08071 PO Box 34, Pacific Grove, CA 93950 (609) 589-2049 Fax (609) 785-1766 (408) 647-8363 Fax (408) 647-8483 Eglise de la Trinité, Cherbourg, France, very clear. The white spot at the top is the moon, of course! The wind had some- [email protected] [email protected] by Christian Becot times gusts and there were blasts which Wolfgang Bieck Craig Wilson This rare night KAPhoto was taken May shaked and rocked the cradle all the time. Am Britzenberg 23 7210 Harvest Hill Road 31, 1996. The kite was Christian’s own Usually at night, I never get enough wind, 29549 Bad Bevensen, Cermany Madison, WI 53717 Crico III; the camera was a Konica Hexar, as it just faints with the daylight. That (+49) 5821 24 43 (608) 831-6770 set at f.2 with Fuji ISO 1600 film. “The shut- time, a storm was just going away, and I [email protected] [email protected] ter was such that it could not use speed had enough.” • æ 4 the aerial eye winter 1997 5
aerial video: get the picture legally the “how” of radio control by STEPHEN JOINER (KC6QFR), North Hollywood, California by PETER van ERKEL, Amsterdam, The Netherlands
After being encouraged by a few men- 1. GET LEGAL Most R/C systems used for KAP are so- generates also tions of aerial video in earlier issues of the Most video transmitters worth messing called digital proportional systems with a pulse signal aerial eye, I was sorry to read in the Winter with are built for licensed ATV operators. two, four, or more channels. “Digital” proportional 1996 issue that several of our mainstay con- To go on the air with one legally in the means nothing more than that the output to the move- tributors had apparently lost enthusiasm USA, you need a piece of paper from Wash- of the transmitter is switched on and off. ment of the for video and sold or mothballed their sys- ington D.C. that says you can. “Proportional” means that the the time the servo axle (po- tems. transmitter is switched off is proportional tentiometer). Nevertheless, it has become common to to the movement of the joystick on the The consensus seemed to be that video see advertised in electronics publications a This pulse transmitter case. was intrusive to the KAP experience, and variety of micro-video transmitters tuned signal is then not the useful tool (much less the wave of to operate on the amateur bands and even Each channel is represented by a pulsing compared to the future) that I believe on vacant standard TV signal, whose pulse duration depends on the pulse sig- it to be. channels, yet many of the position of the joystick. The output sig- nal from the receiver. Depending on the Certainly there are pit- these ads bear only a nal of the transmitter contains information difference between these pulses, the servo falls on the road to video very fine print footnote— for all of the channels in use, one after the motor is turned to the right or the left until Valhalla, and in the pro- if even that—casually other, in a so-called pulse train. the pulses have the same duration. When cess of getting a Techni- mentioning that a license This is like a kite train, one pulse (kite) they do, the displacement of the servo axle cian's class license and is required to use their after the other, separated by a fixed time potentiometer on the receiving end is the spending a few years put- product. (connecting lines), preceded by a longer same as the displacement of another po- tentiometer connected to the joystick on ting ATV (amateur televi- Beware the tempta- fixed time (the kite line). This signal train is the transmitter. sion) equipment and tions of operating such repeated 50 or 60 times per second. 35mm cameras on kites equipment “bootleg” In the case of a two-channel system, the FOUR FOR THE PRICE OF TWO and helium balloons, I've (sans license), even in this output of the transmitter is switched off stumbled into most of When I first started to use an R/C sys- era of Federal Communi- and on twice every 20 milliseconds. Most tem, I bought a Robbe Economic two chan- them. Steve’s video rig, sans 35mm camera. cations Commission systems use a pulse with of 1.5 msec if the 915 mhz transmitter on left, nel set. This set is now sold as the Futaba All that trial-and-error downsizing! The good joystick is in the rest position, 1 msec if the video card camera below Attack II. convinced me that the li- news is that now there's joystick is in the left/down position, and 2 censed amateur route is no excuse not to get your msec if the joystick is in the right/up posi- Looking at the set at component level, I not just the legal thing to do, but also the “ticket” anyhow. You won't have to spend tion. found that at the transmitter control cir- cuit two inputs were not used, and in the most direct—and, ultimately, the easiest— countless hours like I did only a few years The receiver on the other end does noth- path to a serviceable video downlink that's ago learning Morse code. The No-Code receiver control circuit two outputs were ing more than detect if the signal from the not used. neither a low-performance toy, nor a high- Technician's Class license now requires transmitter is present or not, and recon- tech pain-in-the-neck. (Actually, I got a pain only a suprisingly easy written test, for structs it if it is. This pulse train is then di- Connecting a potentiometer circuit to in the neck without video, from staring at which study guides are available as close vided; this means the first pulse goes to the unused inputs the same way as the the sky and trying to determine with any as your humble Radio Shack outlet. the first servo, the second to the second used channels brought the two unused accuracy exactly where a 35mm camera at When you pass—and learn a few useful servo, and so on. outputs on the receiver to life, and I had a 450 feet is aimed.) four-channel set. things about transmitters and antennas in A servo is an electric motor that through If you haven't been discouraged by what the process—you can downlink from a kite a reduction gear moves a potentiometer, If you are interested in converting an At- I and/or others before me have said on this or other remotely-controlled aerial vehicle or variable resistor, that is connected to an tack II set to four channels, I can send the subject so far, here are a few of the steps I on alloted bands from 420 mhz all the way electronic circuit. The position of this po- necessary information to you by mail since have trod on the way to a practical video up to 2.4 ghz. And you can do so without tentiometer, through the electronic circuit, it would take too much space here. system. • continued on page 20 • æ 6 the aerial eye winter 1997 7 customize your KAP transmitter pan & tilt circuits shutter release circuit 5k 1k 5k 5k 1k 2.2k by PETER BULTS, Holthees, The Netherlands trim pot trim trim When I started KAPing it was also the in the lower part of this box and act as a button first time that I used an R/C model trans- counterweight when the antenna is ex- mitter. I didn't like it. It is not designed for tended. The control part of the board was black red white black red white our needs and thus it doesn't meet the er- put in a smaller box together with the volt- gonomical standards that should exist for age indicator, which was attached to the the trimmer pots, which are mounted in- The connection between the two boxes KAP. front of the belt under my left hand. side the box. From the central connection of is a 5-conductor cable. For the Futaba F-14 each of the trimmers a wire is soldered to that's enough. Two conductors are used to These standards are, in my opinion: Now to the replacement of the joysticks. the left and right pin of the control board. bring battery power to the control board. • Fixed to your body in a safe way so As in most systems these sticks are made The other three are used to restore the to turn one or more potentiometers (pots). A special situation is the shutter release that you have both hands free to do button. In this case I used a 5k trimmer, a connections between the two parts of the what is necessary In most cases these variable resistors have original board: plus, minus, and control. To value of 5000 Ohms (5 kilohm). Normally such a 1k resistor and a 2.2k resistor in series. • Antenna on your back, controls in complete the wiring you make the connec- thing turns 300 degrees. In an R/C transmit- The 1k resistor is short-circuited by the front of you button. The central pin of the 5k trimmer tions between boxes, boards and sockets. ter the joystick uses only 75 degrees of it. Since our equipment is used under difficult • Controls that stay in the desired is soldered to the left pin on the control This means that the variable part uses conditions, use flexible cable for this. Stiff position about 1.25k of the total. So in fact it is a board. One of the other pins is connected to the middle pin, the 1k resistor and one of wire tends to break easily. • Small so that it is mobile series of three resistors; 1.875k (fixed) - 1.25k (variable) - 1.875k (fixed). the button pins. The other button pin is con- Now everything can be put in place and I had a Futaba F-14 R/C transmitter, and nected to the point where the 1k and the adjusted. Just tune the trimmers so that all that made things a lot easier. In this trans- Since these values are not generally 2.2k resistor meet. The other side of the servos do what they are supposed to do. mitter the electronic circuit board is clearly available in either fixed or variable resis- 2.2 kilohm is wired to the right pin on the If you don't have a Futaba F-14 or if you laid out in two functional parts. One side of tors, I replaced the original parts with a board. If this results in the servo moving in don't like the idea of cutting the circuit it is the servo-control circuit, the other is 5 kilohm “trimmer” pot, a normal pot of 1k the wrong direction just exchange the left board in pieces you can perhaps put the the radio transmitter. There are three con- and another 5k trimmer. The only critical and right wires on the board. whole board in the front box, and just nections between them: plus, minus and value is that of the normal potentiometer. have the batteries and signal. At that spot I cut the board in two. It should be as close as possible to the the- oretical value of 1.25k but not greater. antenna at your back. The radio transmitter part, together with power switch This is important if you want to use the full Or you can at least use antenna, batteries, and power switch, cable jacks 300 degree turn to position the servo and the principles ex- went into one box. That one was to be keep the exact 90 degree rotation of the plained above to re- fixed to a belt behind me. The batteries are place the joysticks servo. The trimmer pots should be at least tilt trimmers 1.875 kilohm. with potentiometers. But be careful if you You'll need two of these re- voltage meter have modified the pan placement assemblies, one for tilt pot servo to endless rota- pan and one for tilt. Install the tion. In that case you normal pots in the control box shutter button need to use a pan con- with the shaft through the box. trol pot with a neutral The central connection point of pan pot center position like a each of these pots is wired to balance control pot for the middle connection point on pan trims a stereo system. the circuit board. Each of the other points is soldered to one shutter trim of the other points of one of • æ 8 the aerial eye winter 1997 9 walkie-talkie pushie-clickie FLiBB’96: picavet über alles by CARL BIGRAS, 4530 Eighth Line Road, Carlsbad Springs, Ontario K0A 1K0, Canada text & photos by BROOKS LEFFLER, editor
When I first got interested in KAP, I cord about four inches long connected the couldn't afford an R/C system. I came up walkie-talkie to the camera's remote shut- with a bright idea; I wasn't sure if it was ter jack. The two microchips were glued to- going to work but it did and it was inex- gether and located under the battery. pensive. This was installed on my first camera rig, My Canon T-90 camera has an electric re- which was a very simple version from Pel- mote shutter release, and I wanted to trig- ham's Penguin Book of Kites [now out of ger it electronically versus using a mechan- print, alas—ed.], built out of plexiglass and ical method. I used a set of Radio Shack a small camera ball head. walkie-talkies with a Morse code button. Now that I have a full remote control The idea was to use the Morse code sig- system for KAP, I still use the walkie-talkie nal sent from one walkie-talkie to the oth- for remote tripod photography. er. Each unit has an oscillator circuit; when • æ you push the Morse code button on one No less than 30 KAPers (and kin) gath- We met at the Gustav Stresemann Insti- walkie-talkie, it transmits a signal (sine ered during the second week of October tute, a conference center by the river Ilme- wave) to the other one, which comes out for “Fesseldrachen-Luftbildtage in Bad Be- nau at the edge of Bad Bevensen. Attend- as a beep. As long as the button is pushed vensen 1996” (Kite Aerial Photography ees from out of the area were housed in, the other unit would beep. Days in Bad Bevensen), or FLiBB for short there as well, and we took all of our meals Only one unit required modification. I (chief organizer Wolfgang Bieck loves acro- in the dining hall of the complex. Our cut and bypassed the speaker wires, and nyms). meetings and workshops took place in wired in a small bridge rectifier, which con- Bad Bevensen is an ancient spa in the Il- what was originally the jailyard of a 16th- verted the sine wave (AC) to 5 volts DC at menau River valley about 80 km southeast century gothic courthouse, now converted maximum volume. The DC output was of Hamburg, rolling root-crop farmland to a good-sized meeting room with lots of then connected to a small microchip relay. spotted with small forests of mixed coni- wall space and a low beamed ceiling. The relay contacts were connected to a fers and hardwoods. Lovely country in the As the clan gathered on Monday after- 2.5 mm mini phone jack installed through fall. noon, those who brought rigs with them the walkie-talkie case. A Canon remote Participants came from all over Europe, hung them around the room. Our AKA/ some for the whole week, some just for World Kite Museum traveling photo exhibit the final weekend. Early arrivals included occupied one long wall, and individual KAP- cut speaker wires or install event co-organizers Ralf Beutnagel, Otto ers succeeded in filling most of the rest of switch for walkie-talkie use Böhnke, and Harald Prinzler and family, the walls with pictures. Monday evening plus Norbert Gabriel, Hermann Graff, Ulrich was spent socializing and soaking up all relay Monsees, Christian Kolz, and Ralf Vehling this inspiration. from Germany; Dr. Christian Loibl from Aus- Tuesday started with Wolfgang’s hands- tria; Peter van Erkel and Peter Bults from on workshop building SUMIPIs (that’s Bieck- bridge rectifier the Netherlands, and me from the USA. speak for SubMiniature Picavets) out of For the first four days, I was the only partic- sheet aluminum and miniature ball- to camera jack ipant who didn’t speak much german. bearing blocks. In the afternoon Ralf Beut- Two of the Germans didn’t speak any eng- nagel gave a slide talk about KAP modifica- lish, so when in doubt, german won. tions to compact cameras. Later we set • continued on page 24 10 the aerial eye winter 1997 11
The relay has a small potentiometer Iowa, published a design for a relay of his trigger your shutter electrically that is turned to adjust the point in the ra- own making, which could be modified to dio channel’s range at which the circuit is activate sequential relay outputs. I have by CRIS BENTON, Berkeley, California, & RANDY BOLLINGER, Ferguson, Missouri closed and triggers the shutter. The ad- used Mike’s relays in two Rebel-based rigs justment is sufficiently accurate that I use I have built for others. Mike has promised An increasing number of KAPers are FROM CRIS BENTON: my rudder channel’s trim tab for firing the to produce these relays (which he calls triggering their camera’s shutter electrical- One interesting aspect of the Canon shutter. the Sure-Shot™ Radio Control Shutter Re- ly with a relay instead of mechanically Rebel camera is its small side-mounted My High Sky relay has been used for lease Gizmo), but they haven’t quite made with a servo, which makes the rig more electrical jack for remote control. The jack about 10 rolls of film so far and it has it to production yet. Contact info for Mike reliable, lighter, and less complicated. accepts a 3/32" sub-miniature stereo plug. worked fine for me. The one change I is also included so you may pester him di- Several cameras have electrical remote My local camera dealer kindly (amazing- would make is to use a right-angle stereo rectly. control built-in, such as most Ricohs and ly?) let me disassemble Canon's wired re- plug that hugs the camera body, but I Elsewhere in this issue you’ll find infor- some models of the Canon Rebel, but mote control to check its workings. Slid- have been unable to find one. mation on how to replace the joystick on many compact cameras may be easily ing the remote’s switch halfway closes a FROM RANDY BOLLINGER: your transmitter with a shutter pushbut- wired for electric triggering, such as the circuit between the stereo plug tip and …In KAP, every ounce counts…every ton. This conversion is a natural partner Olympus Stylus/Mu and the Rollei Prego. the plug base. I assume this is the equiva- amp counts. The use of an electronic to the electric shutter release. —bgl Ralf Beutnagel did a slide lecture on lent of pressing the shutter button half- shutter will provide a reduction for both. • æ way for exposure and focus lock. Complet- this subject at FLiBB, and the main point …I found that Tower Hobbies sells a re- ing the travel of the remote’s switch adds he made is, don’t be afraid to look inside lay called the RAM Simple R/C Switch…. shutter relay sources the middle band of the stereo plug to the your camera to see if it’s possible to wire The advantage of this relay is not only circuit. The camera's shutter fires when High Sky On/Off Controller: it for electric shutter release. (The other- weight reduction and lower amp usage. It all three “zones” of the stereo plug are in High Sky wise excellent Yashica T-4, alas, is not an will also provide us the opportunity to fin- electrical contact. The Canon can be 203 Bison Ridge easy one to wire, according to Ralf.) ish shooting a roll [when the batteries run placed in a mode where only one expo- Nappanee, IN 46550 down too far to operate servos] by using Two KAPers have sent in articles on this sure will result from this type of switch (219) 773-4705. the rig in a fixed position. There’s still subject, which we have abstracted below. closure no matter how long it lasts. enough voltage to operate the shutter. Sheldon's Hobbies (catalog) The next challenge was finding a means San Jose, California If you’re already using a fixed-position for the radio receiver to produce a similar (800) 228-3237 The High Sky relay on rig with one servo for shutter, think of the circuit closure. Here I used an electric sail- Cris Benton’s new Rebel rig hours of shooting time you will have— plane on/off control made by High Sky in RAM Simple R/C Switch your camera may go dead before your Indiana [see box, page 11], which sells for rig’s battery. RAM about $20.00. It is slightly larger than a box 229 E. Rollins Road of matches and weighs one ounce—about ...... Round Lake Beach, IL 60073 the same as the micro servo it replaces on FLiBB participants using electric shut- (847)740-5220 my rig. ters said they felt that better results Tower Hobbies (catalog) High Sky's device is basically a small re- could sometimes be achieved with a two- PO Box 9078 lay that can be actuated by any radio channel sequential relay, with one chan- Champaign, IL 61828-9078 channel. One end of the device plugs into nel activating the midpoint focus lock (800) 637-4989(217) 398-3636 the radio receiver. At the other end you and the other triggering the shutter. Re- can connect two wires to be either a nor- lays are available in Germany which will Sure-Shot R/C Shutter mally-open or normally-closed circuit. do this. We don’t have source informa- Release Gizmo For firing the shutter I built a cable that tion, but Wolfgang Bieck can provide Mike LeDuc connects the sub-mini stereo plug tip and same. His address is on page 2. 137 19th Street NW plug base to one wire and the stereo Long ago in KAPWA TECHNIQUE, elec- Cedar Rapids, IA 52405 plug's middle zone to a second wire. tronic KAPer Mike LeDuc of Cedar Rapids, These wires are then routed to the nor- mally-open connectors on the relay.
12 the aerial eye winter 1997 13
MONITORING THE FUNCTIONS • there are no modification at all in the two channels—many functions transmitter, nor on the receiver or the The multi-contact servo is connected on servos by CHRISTIAN BECOT, Tourlaville, France the throttle channel. The joystick is offset and trimmed so that the blades of the ro- • you may imagine other additional functions Because we need pan, tilt, and shutter the copper coat with a small grinder tary switch are in the neutral position control, most KAPers are using four- mounted on a mini electric drill, or do it when the joystick is released. • you save batteries: only one servo is channel remote control radios. Two- the professional way with acid. A flick downward of the joystick will trig- fed all the time, and it is working ef- fortlessly channel radios are much less expensive. The diagram shows one example of this ger the shutter. With the addition of the multi-contact sys- application. Many others are possible. Only when the joystick is held in either • the system can be combined with any tem to a 2-channel radio, all functions are the pan or the tilt position is the relevant other arrangement. available at reasonable cost. THE HOEDIC APPARATUS servo connected. At that time is its possi- DISADVANTAGES The principle is to use one servo as a dis- Hoedic is a small island off the coast of ble with the second joystick to command patching center for the control signal, and Brittany in France. Pascal and Marie man- the servo. When the rig is pointing where • The tilt servo is not under power all of feed and control each function one by one. age the Fîle a Voile center where you can you wish, you suddenly release the throttle the time. The consequence is that it make and fly kites. The island is car free! joystick. The arm will quickly come back will hold the inclination angle of the camera only by the inertia of the tilt You can also use their KAP rig which is to the neutral position, and the pan and tilt To do this, a rotary switch is made from servo. an electronic plate with copper coating on controlled by a 2-channel radio and the will remain as they have been set. one face [i.e., a piece of blank circuit board multi-contact system here described: • If the camera is heavy and the center ADVANTAGES of gravity has not been properly set, material] which will be installed on the ser- The minus wire is connected for tilt or • cost is less than a 4 channel radio the camera may slowly tilt upward or vo. An arm rotated by the servo supports pan servos only when the arm is in the cor- downward. To avoid this problem, in- twin metal blades giving different electrical rect position. You may also switch the plus • it is practical as your settings remain stall a brake or rebalance the rig. contacts at each position of the arm. wire if you prefer, but never switch the unchanged as long as you wish For preparing the plate, you can scrape control wire, or you will get troubles. • æ
multi-contact switch the hoedic rig weight 565g w/servo behind + c - pan servo - c + - c + and gears receiver receiver tilt servo pan servo
+ c -
rotary switch
contact arm camera switch servo
copper coating tilt servo backing board direct drive camera wired for 6v lithium electric shutter release battery 14 the aerial eye winter 1997 15 aerial gallery