An inexpensive circuit size postage stamp reverses direction travel proportional servo Its simple design using commonly available electronic components makes great project RC modeler SERVO REVERSER have kidding would need very oldest RC systems allow modeler reverse direction rotation servo just flip switch case newest transmitters couple simple programming steps Based might conclude need servo reversing gone forever However case Highly maneuverable aerobatic airplanes Extras Sukhois Caps name few becoming increasingly popular competition sport fliers trend larger models more-powerful engines need reliable control-surface actuation critical ever very effective method controlling highly loaded flying surfaces minimize length complexity control linkages mounting servos very near flying surfaces control case split elevators popular practice mount servo directly side fuselage just below horizontal stabilizer Both servos can driven single channel using Y-harness extension cable pushrods attached same side servo arm ie top bottom servo motors must rotate opposite directions same control input receiver Therefore servo needs reversed respect other may tempted mount servos different vertical positions side fuselage pushrods can come off opposite side servos maintaining relatively straight path elevator control horns However since two geometries provide equal elevator throw extremes travel direction acceptable solution result induced twisting moment elevator positions away neutrala serious 30 Model Aviation * Graphic Design Carla Kunz filtered voltage supply V1 RiP2 servo V4 receiver rIrc3 110111 15101 IIP8 04 23 Vt rWr 12FF problem roll-sensitive aerobatic model alternative maintain mirror-image symmetry elevator control installation force servo rotate direction opposite other Both control linkages should come off bottom servo top control split elevators just number situations could require servo reversing Flap actuation throttle control multiengine aircraft other useful examples Y-harness applications several ways approach task reversing servo first physically modify servo reverse its rotation taking servo apart reversing electrical connections motor feedback potentiometer procedure often complicated fact motor can attached directly printed-circuit board motor generally glued case more-expensive ballbearing servos sometimes requiring servo housing broken away replaced second approach could attach servos separate channels programmable computer radio system Using electronic mixing channel could reversed slaved elevator channel seems like great solution indeed will manufacturers radios figure out need type dual servo control However try now will find radio systems am aware transmitter trim lever will affect master servo leaving slave servo unchanged third optionthe solution presented hereis insert electronic device between Y-harness servos would intercept electronic control signals convert necessary drive servo reverse concept inline electronic servo reverser new can purchased number RC manufacturers generally will work pretty well article illustrates important role devices still play RC modeling presents simple inexpensive design can readily built modelers fairly significant shortcoming shared commercially available reversers use onboard centering adjustment usually takes form carbon film potentiometer particularly susceptible temperature drift can cause unwanted changes trim reversed servo ambient temperature changes avoided design Theory Operation understand electronic servo reverser works first necessary review control signals sent receiver servo three wires connecting servo receiver first two supply plus minus voltage battery pack often red black respectively third wire carries pulses direct motion servo positive pulses occur rate about 60 per second vary width between about l-2ms milliseconds thousandths second pulse width lms sends servo output limit rotation direction 2ms limit other reverser circuit based common readily available 555 timer chip Actually 556 version used two independent 555s single 14-pin package Figure 3 shows schematic servo reverser design Figure 4 presents timing diagram useful understanding operates Servo motors tend draw current small gulps lasting 1-2 ms places small ripple receiver battery voltage servo motion particularly noticeable using high-torque ball-bearing servos Although reverser will continue work over wide battery voltage range trim changes rapid voltage fluctuations filtered could occasionally May1997 35 II a Input pulee receiver timer bInverted trigger discharge pulse pin Sdelayed P7 2/3 V1 c Charging signaltimer 2 pins 2 12 I I terminated II II II d Filtered trigger pulse pin 8 timer2 grnet\ aOutput pulse I I s I llxR6sC2 II Figure 1Timing diagram Figure 2 Figure 3 -v receiver ~ servos installed control arms opposite sides servo such shown figures b unequal elevator throw will result order maintain mirror image mechanical symmetry servo must reversed 6 # partsDescriptionPart number# packages 47 resistor271-1 105 310k resistor271-1335 347k resistor271-1342 270k 1% metal film resistorN/A 470pF ceramic disk capacitor272-125 2OlpF PC-mount capacitor272-1065 22pF radial-lead electrolytic capacitor272-1026 2MPS2222A npn transistor276-2009 56 dual timer276-1728 6 ResistorsCapacitors Rl10kbrown black orange*Cl22pF R247kyellow purple blackC20111F** R310kbrown black orangeC301sF R447kyellow purple orangeC4470pF*** R547kyellow purple orange R6270kred purple yellowTransistors R710kbrown black orangeQiMPS2222A R847kyellow purple orangeQ2MPS2222A * The last resistor color band gold 5% resistors ** Ot1iF capacitor labeled 103 F capacitor labeled 471 6 Manufacturer Airtronics JR RCD/Hitec Futaba Positive voltage B black / red red center wire red center wire red center wire Negative voltage black center wire brown black black Signal C D black orange yellow wbite 36 Model Aviation Full-size ImOw ft 2X cause small amount mechanical chatter observed servo output another servo moved addition previously mentioned temperature drift has common complaint associated some commercially available designs Referring schematic shown Figure 2 resistor Ri capacitor Cl transistor Qi form filtered voltage source supplies entire circuit suppresses rapid voltage flutter Resistor R2 acts current limit protect Ql case accidental short circuit What about centering adjustment Most commercial units include feature expense trim settings may vary excessively changing temperature chose use fixed value 270k Q R6 believing provide adjustment would redundant centering method electronic trim mechanical adjustment would have used servo reverser circuit place great advantage fixed setting allows 1% metal film resistor used has very good temperature stability CONSTRUCTION An important goal able build circuit components could easily purchased electronics supply such Radio Shack successful except resistor R6 270k 1% metal film resistor should easily obtained another local electronics supply best way make circuit board product called Press-n-Peel blue plastic film can run through conventional photocopy machine directprinted laser printer image should copied onto dull side film ironed onto copper-clad board Radio Shack 276-1499 using household iron airplane film sealing iron experimenting best temperature found useful securely tape film board along edge could carefully peel back small portion test adhesion pattern board After successful image transfer board etched solution ferric chloride Radio Shack 276-1535 30-60 minutes until unwanted copper gone Note blank board two-sided copper will removed back side board large enough simultaneously make up 20 printed-circuit boards After etching mounting holes should drilled #65 bit easily accomplished since copper surrounding hole location accurately guides drill modelers interested building circuit want manufacture PC board need 270k resistor may contact author Alternatively complete unassembled kit minus servo connectors can obtained components should inserted side opposite copper circuit pattern resistors should mounted vertically Pay special attention May1997 39 THE BEST IN SCALE ELITE PLANS Dennis Bryant Dennis Bryant Englands best scale designers Dennis also top scale builder flyer Dennis has own plan service England Bob Holman has always Dennis agent USA 26 different plans available Accessories available plans Designers like Dennis Bryant will sell plan tilt model has built successfully test flown Feisler Storch 1/6th scale 96 span Power 90-1204 stroke Plans/templates $4000 postage Laser cat main wing ribs $2000 Epoxy glass cowl $3500 age $500 Photo Pac $1440 age Scale drawing $625 postage LASER cut parts $16000 postage Landing gear alco legs $21000 Balsa ad spruce material par $6000 p Comolete nackage $51000 0 postaae Best Scale Catalog $700BOB HOLMAN PLANS PO BOX 741 MA New Laser Cut Parts Kits SAN BERNARDINO CA 92402 909-8893959 BHPLANS@AOLCOM ICi Cl Qi Q2 since direction installed very important Capacitor Cl should have lead marked efully solder installed components copper circuit pattern taking care avoid solder bridges across gaps between traces sure use good-quality resincore electronics-grade solder brighten copper traces fine steel wool Scotchbrite pad before starting Advice and/or instruction fellow modeler circuit-assembly experience could useful excess resin left soldering can easily removed solvent such lacquer thinner use K&B Super Poxy thinner since thats what have shop epoxy brush brisfies cut back Input/output leads can obtained cutting servo extension cable appropriate particular radio system half Table 3 summarizes wire color codes typically used some common radio systems Using Figure 3 carefully attach leads according chart Note wires both input output leads attached points B Airtronics users should cautioned V V- wires reversed servo harness Futaba JR RCD radio systems Since Airtronics harness has two wires same color black carefully note denoted center wire Table 3 Installation operation use servo reverser circuit simply plugged between receiver arm y harness servo nice touch achieved sliding finished circuit short length one-inch heat-shrink tubing careful overheat circuit shrinking desired second set output leads can attached points B C resulting built-in Y-harness like wrap finished circuit layer -inch latex foam held couple rubber bands shield against engine vibration answers questions additional information about servo reverser can contacted Internet cbdane@pacbellnet t Dane 678 Crane Ave Livermore CA 94550 Sources Press-n-Peel Electronics Corp Van Nuys CA 91411 818 997-1806 Circuit board Avnilable $10 author Complete kit $15 author 270k resistor SASE author no other charge May1997 41 SUPERFAST LOWDELIVERY PRICES I1-11 IL LCALWAYS MINIATURE BEARINGS FOR HOBBY & INDUSTRY lete Product LinesWe Have Premium UlbaSeal frictionless sealed maintenance-free bearingsthe Largest R/C CarsEeeuePowu bearings engineered strength & durability Tucks, High-Speal hgh heat engne bear ngsInventory BoatsStandard US Metr c s zesand PlanesAsk us about MIDAS TOUCH Other F ne ProductsWidest &Send $3 00 CatalogsSelection Helicopters Deaie P og ama Ava abe BOCA BEARING Co-IN STOCK 7040W Palmetto Park Rd Suite 2304 Ml Boca Raton FL 33433 Tel 407 998 0004 407 908 0110 W USA CANADA CALL TOLL FREE 800-332-3256 DA . .- FOR PRiCtS & INFO FKG MUD DUCK AVIAIION 7118 Westmoreland Dr Worrenton VA 22186 15401 347-1134
Edition: Model Aviation - 1997/05
Page Numbers: 30, 35, 36, 39, 41
An inexpensive circuit size postage stamp reverses direction travel proportional servo Its simple design using commonly available electronic components makes great project RC modeler SERVO REVERSER have kidding would need very oldest RC systems allow modeler reverse direction rotation servo just flip switch case newest transmitters couple simple programming steps Based might conclude need servo reversing gone forever However case Highly maneuverable aerobatic airplanes Extras Sukhois Caps name few becoming increasingly popular competition sport fliers trend larger models more-powerful engines need reliable control-surface actuation critical ever very effective method controlling highly loaded flying surfaces minimize length complexity control linkages mounting servos very near flying surfaces control case split elevators popular practice mount servo directly side fuselage just below horizontal stabilizer Both servos can driven single channel using Y-harness extension cable pushrods attached same side servo arm ie top bottom servo motors must rotate opposite directions same control input receiver Therefore servo needs reversed respect other may tempted mount servos different vertical positions side fuselage pushrods can come off opposite side servos maintaining relatively straight path elevator control horns However since two geometries provide equal elevator throw extremes travel direction acceptable solution result induced twisting moment elevator positions away neutrala serious 30 Model Aviation * Graphic Design Carla Kunz filtered voltage supply V1 RiP2 servo V4 receiver rIrc3 110111 15101 IIP8 04 23 Vt rWr 12FF problem roll-sensitive aerobatic model alternative maintain mirror-image symmetry elevator control installation force servo rotate direction opposite other Both control linkages should come off bottom servo top control split elevators just number situations could require servo reversing Flap actuation throttle control multiengine aircraft other useful examples Y-harness applications several ways approach task reversing servo first physically modify servo reverse its rotation taking servo apart reversing electrical connections motor feedback potentiometer procedure often complicated fact motor can attached directly printed-circuit board motor generally glued case more-expensive ballbearing servos sometimes requiring servo housing broken away replaced second approach could attach servos separate channels programmable computer radio system Using electronic mixing channel could reversed slaved elevator channel seems like great solution indeed will manufacturers radios figure out need type dual servo control However try now will find radio systems am aware transmitter trim lever will affect master servo leaving slave servo unchanged third optionthe solution presented hereis insert electronic device between Y-harness servos would intercept electronic control signals convert necessary drive servo reverse concept inline electronic servo reverser new can purchased number RC manufacturers generally will work pretty well article illustrates important role devices still play RC modeling presents simple inexpensive design can readily built modelers fairly significant shortcoming shared commercially available reversers use onboard centering adjustment usually takes form carbon film potentiometer particularly susceptible temperature drift can cause unwanted changes trim reversed servo ambient temperature changes avoided design Theory Operation understand electronic servo reverser works first necessary review control signals sent receiver servo three wires connecting servo receiver first two supply plus minus voltage battery pack often red black respectively third wire carries pulses direct motion servo positive pulses occur rate about 60 per second vary width between about l-2ms milliseconds thousandths second pulse width lms sends servo output limit rotation direction 2ms limit other reverser circuit based common readily available 555 timer chip Actually 556 version used two independent 555s single 14-pin package Figure 3 shows schematic servo reverser design Figure 4 presents timing diagram useful understanding operates Servo motors tend draw current small gulps lasting 1-2 ms places small ripple receiver battery voltage servo motion particularly noticeable using high-torque ball-bearing servos Although reverser will continue work over wide battery voltage range trim changes rapid voltage fluctuations filtered could occasionally May1997 35 II a Input pulee receiver timer bInverted trigger discharge pulse pin Sdelayed P7 2/3 V1 c Charging signaltimer 2 pins 2 12 I I terminated II II II d Filtered trigger pulse pin 8 timer2 grnet\ aOutput pulse I I s I llxR6sC2 II Figure 1Timing diagram Figure 2 Figure 3 -v receiver ~ servos installed control arms opposite sides servo such shown figures b unequal elevator throw will result order maintain mirror image mechanical symmetry servo must reversed 6 # partsDescriptionPart number# packages 47 resistor271-1 105 310k resistor271-1335 347k resistor271-1342 270k 1% metal film resistorN/A 470pF ceramic disk capacitor272-125 2OlpF PC-mount capacitor272-1065 22pF radial-lead electrolytic capacitor272-1026 2MPS2222A npn transistor276-2009 56 dual timer276-1728 6 ResistorsCapacitors Rl10kbrown black orange*Cl22pF R247kyellow purple blackC20111F** R310kbrown black orangeC301sF R447kyellow purple orangeC4470pF*** R547kyellow purple orange R6270kred purple yellowTransistors R710kbrown black orangeQiMPS2222A R847kyellow purple orangeQ2MPS2222A * The last resistor color band gold 5% resistors ** Ot1iF capacitor labeled 103 F capacitor labeled 471 6 Manufacturer Airtronics JR RCD/Hitec Futaba Positive voltage B black / red red center wire red center wire red center wire Negative voltage black center wire brown black black Signal C D black orange yellow wbite 36 Model Aviation Full-size ImOw ft 2X cause small amount mechanical chatter observed servo output another servo moved addition previously mentioned temperature drift has common complaint associated some commercially available designs Referring schematic shown Figure 2 resistor Ri capacitor Cl transistor Qi form filtered voltage source supplies entire circuit suppresses rapid voltage flutter Resistor R2 acts current limit protect Ql case accidental short circuit What about centering adjustment Most commercial units include feature expense trim settings may vary excessively changing temperature chose use fixed value 270k Q R6 believing provide adjustment would redundant centering method electronic trim mechanical adjustment would have used servo reverser circuit place great advantage fixed setting allows 1% metal film resistor used has very good temperature stability CONSTRUCTION An important goal able build circuit components could easily purchased electronics supply such Radio Shack successful except resistor R6 270k 1% metal film resistor should easily obtained another local electronics supply best way make circuit board product called Press-n-Peel blue plastic film can run through conventional photocopy machine directprinted laser printer image should copied onto dull side film ironed onto copper-clad board Radio Shack 276-1499 using household iron airplane film sealing iron experimenting best temperature found useful securely tape film board along edge could carefully peel back small portion test adhesion pattern board After successful image transfer board etched solution ferric chloride Radio Shack 276-1535 30-60 minutes until unwanted copper gone Note blank board two-sided copper will removed back side board large enough simultaneously make up 20 printed-circuit boards After etching mounting holes should drilled #65 bit easily accomplished since copper surrounding hole location accurately guides drill modelers interested building circuit want manufacture PC board need 270k resistor may contact author Alternatively complete unassembled kit minus servo connectors can obtained components should inserted side opposite copper circuit pattern resistors should mounted vertically Pay special attention May1997 39 THE BEST IN SCALE ELITE PLANS Dennis Bryant Dennis Bryant Englands best scale designers Dennis also top scale builder flyer Dennis has own plan service England Bob Holman has always Dennis agent USA 26 different plans available Accessories available plans Designers like Dennis Bryant will sell plan tilt model has built successfully test flown Feisler Storch 1/6th scale 96 span Power 90-1204 stroke Plans/templates $4000 postage Laser cat main wing ribs $2000 Epoxy glass cowl $3500 age $500 Photo Pac $1440 age Scale drawing $625 postage LASER cut parts $16000 postage Landing gear alco legs $21000 Balsa ad spruce material par $6000 p Comolete nackage $51000 0 postaae Best Scale Catalog $700BOB HOLMAN PLANS PO BOX 741 MA New Laser Cut Parts Kits SAN BERNARDINO CA 92402 909-8893959 BHPLANS@AOLCOM ICi Cl Qi Q2 since direction installed very important Capacitor Cl should have lead marked efully solder installed components copper circuit pattern taking care avoid solder bridges across gaps between traces sure use good-quality resincore electronics-grade solder brighten copper traces fine steel wool Scotchbrite pad before starting Advice and/or instruction fellow modeler circuit-assembly experience could useful excess resin left soldering can easily removed solvent such lacquer thinner use K&B Super Poxy thinner since thats what have shop epoxy brush brisfies cut back Input/output leads can obtained cutting servo extension cable appropriate particular radio system half Table 3 summarizes wire color codes typically used some common radio systems Using Figure 3 carefully attach leads according chart Note wires both input output leads attached points B Airtronics users should cautioned V V- wires reversed servo harness Futaba JR RCD radio systems Since Airtronics harness has two wires same color black carefully note denoted center wire Table 3 Installation operation use servo reverser circuit simply plugged between receiver arm y harness servo nice touch achieved sliding finished circuit short length one-inch heat-shrink tubing careful overheat circuit shrinking desired second set output leads can attached points B C resulting built-in Y-harness like wrap finished circuit layer -inch latex foam held couple rubber bands shield against engine vibration answers questions additional information about servo reverser can contacted Internet cbdane@pacbellnet t Dane 678 Crane Ave Livermore CA 94550 Sources Press-n-Peel Electronics Corp Van Nuys CA 91411 818 997-1806 Circuit board Avnilable $10 author Complete kit $15 author 270k resistor SASE author no other charge May1997 41 SUPERFAST LOWDELIVERY PRICES I1-11 IL LCALWAYS MINIATURE BEARINGS FOR HOBBY & INDUSTRY lete Product LinesWe Have Premium UlbaSeal frictionless sealed maintenance-free bearingsthe Largest R/C CarsEeeuePowu bearings engineered strength & durability Tucks, High-Speal hgh heat engne bear ngsInventory BoatsStandard US Metr c s zesand PlanesAsk us about MIDAS TOUCH Other F ne ProductsWidest &Send $3 00 CatalogsSelection Helicopters Deaie P og ama Ava abe BOCA BEARING Co-IN STOCK 7040W Palmetto Park Rd Suite 2304 Ml Boca Raton FL 33433 Tel 407 998 0004 407 908 0110 W USA CANADA CALL TOLL FREE 800-332-3256 DA . .- FOR PRiCtS & INFO FKG MUD DUCK AVIAIION 7118 Westmoreland Dr Worrenton VA 22186 15401 347-1134
Edition: Model Aviation - 1997/05
Page Numbers: 30, 35, 36, 39, 41
An inexpensive circuit size postage stamp reverses direction travel proportional servo Its simple design using commonly available electronic components makes great project RC modeler SERVO REVERSER have kidding would need very oldest RC systems allow modeler reverse direction rotation servo just flip switch case newest transmitters couple simple programming steps Based might conclude need servo reversing gone forever However case Highly maneuverable aerobatic airplanes Extras Sukhois Caps name few becoming increasingly popular competition sport fliers trend larger models more-powerful engines need reliable control-surface actuation critical ever very effective method controlling highly loaded flying surfaces minimize length complexity control linkages mounting servos very near flying surfaces control case split elevators popular practice mount servo directly side fuselage just below horizontal stabilizer Both servos can driven single channel using Y-harness extension cable pushrods attached same side servo arm ie top bottom servo motors must rotate opposite directions same control input receiver Therefore servo needs reversed respect other may tempted mount servos different vertical positions side fuselage pushrods can come off opposite side servos maintaining relatively straight path elevator control horns However since two geometries provide equal elevator throw extremes travel direction acceptable solution result induced twisting moment elevator positions away neutrala serious 30 Model Aviation * Graphic Design Carla Kunz filtered voltage supply V1 RiP2 servo V4 receiver rIrc3 110111 15101 IIP8 04 23 Vt rWr 12FF problem roll-sensitive aerobatic model alternative maintain mirror-image symmetry elevator control installation force servo rotate direction opposite other Both control linkages should come off bottom servo top control split elevators just number situations could require servo reversing Flap actuation throttle control multiengine aircraft other useful examples Y-harness applications several ways approach task reversing servo first physically modify servo reverse its rotation taking servo apart reversing electrical connections motor feedback potentiometer procedure often complicated fact motor can attached directly printed-circuit board motor generally glued case more-expensive ballbearing servos sometimes requiring servo housing broken away replaced second approach could attach servos separate channels programmable computer radio system Using electronic mixing channel could reversed slaved elevator channel seems like great solution indeed will manufacturers radios figure out need type dual servo control However try now will find radio systems am aware transmitter trim lever will affect master servo leaving slave servo unchanged third optionthe solution presented hereis insert electronic device between Y-harness servos would intercept electronic control signals convert necessary drive servo reverse concept inline electronic servo reverser new can purchased number RC manufacturers generally will work pretty well article illustrates important role devices still play RC modeling presents simple inexpensive design can readily built modelers fairly significant shortcoming shared commercially available reversers use onboard centering adjustment usually takes form carbon film potentiometer particularly susceptible temperature drift can cause unwanted changes trim reversed servo ambient temperature changes avoided design Theory Operation understand electronic servo reverser works first necessary review control signals sent receiver servo three wires connecting servo receiver first two supply plus minus voltage battery pack often red black respectively third wire carries pulses direct motion servo positive pulses occur rate about 60 per second vary width between about l-2ms milliseconds thousandths second pulse width lms sends servo output limit rotation direction 2ms limit other reverser circuit based common readily available 555 timer chip Actually 556 version used two independent 555s single 14-pin package Figure 3 shows schematic servo reverser design Figure 4 presents timing diagram useful understanding operates Servo motors tend draw current small gulps lasting 1-2 ms places small ripple receiver battery voltage servo motion particularly noticeable using high-torque ball-bearing servos Although reverser will continue work over wide battery voltage range trim changes rapid voltage fluctuations filtered could occasionally May1997 35 II a Input pulee receiver timer bInverted trigger discharge pulse pin Sdelayed P7 2/3 V1 c Charging signaltimer 2 pins 2 12 I I terminated II II II d Filtered trigger pulse pin 8 timer2 grnet\ aOutput pulse I I s I llxR6sC2 II Figure 1Timing diagram Figure 2 Figure 3 -v receiver ~ servos installed control arms opposite sides servo such shown figures b unequal elevator throw will result order maintain mirror image mechanical symmetry servo must reversed 6 # partsDescriptionPart number# packages 47 resistor271-1 105 310k resistor271-1335 347k resistor271-1342 270k 1% metal film resistorN/A 470pF ceramic disk capacitor272-125 2OlpF PC-mount capacitor272-1065 22pF radial-lead electrolytic capacitor272-1026 2MPS2222A npn transistor276-2009 56 dual timer276-1728 6 ResistorsCapacitors Rl10kbrown black orange*Cl22pF R247kyellow purple blackC20111F** R310kbrown black orangeC301sF R447kyellow purple orangeC4470pF*** R547kyellow purple orange R6270kred purple yellowTransistors R710kbrown black orangeQiMPS2222A R847kyellow purple orangeQ2MPS2222A * The last resistor color band gold 5% resistors ** Ot1iF capacitor labeled 103 F capacitor labeled 471 6 Manufacturer Airtronics JR RCD/Hitec Futaba Positive voltage B black / red red center wire red center wire red center wire Negative voltage black center wire brown black black Signal C D black orange yellow wbite 36 Model Aviation Full-size ImOw ft 2X cause small amount mechanical chatter observed servo output another servo moved addition previously mentioned temperature drift has common complaint associated some commercially available designs Referring schematic shown Figure 2 resistor Ri capacitor Cl transistor Qi form filtered voltage source supplies entire circuit suppresses rapid voltage flutter Resistor R2 acts current limit protect Ql case accidental short circuit What about centering adjustment Most commercial units include feature expense trim settings may vary excessively changing temperature chose use fixed value 270k Q R6 believing provide adjustment would redundant centering method electronic trim mechanical adjustment would have used servo reverser circuit place great advantage fixed setting allows 1% metal film resistor used has very good temperature stability CONSTRUCTION An important goal able build circuit components could easily purchased electronics supply such Radio Shack successful except resistor R6 270k 1% metal film resistor should easily obtained another local electronics supply best way make circuit board product called Press-n-Peel blue plastic film can run through conventional photocopy machine directprinted laser printer image should copied onto dull side film ironed onto copper-clad board Radio Shack 276-1499 using household iron airplane film sealing iron experimenting best temperature found useful securely tape film board along edge could carefully peel back small portion test adhesion pattern board After successful image transfer board etched solution ferric chloride Radio Shack 276-1535 30-60 minutes until unwanted copper gone Note blank board two-sided copper will removed back side board large enough simultaneously make up 20 printed-circuit boards After etching mounting holes should drilled #65 bit easily accomplished since copper surrounding hole location accurately guides drill modelers interested building circuit want manufacture PC board need 270k resistor may contact author Alternatively complete unassembled kit minus servo connectors can obtained components should inserted side opposite copper circuit pattern resistors should mounted vertically Pay special attention May1997 39 THE BEST IN SCALE ELITE PLANS Dennis Bryant Dennis Bryant Englands best scale designers Dennis also top scale builder flyer Dennis has own plan service England Bob Holman has always Dennis agent USA 26 different plans available Accessories available plans Designers like Dennis Bryant will sell plan tilt model has built successfully test flown Feisler Storch 1/6th scale 96 span Power 90-1204 stroke Plans/templates $4000 postage Laser cat main wing ribs $2000 Epoxy glass cowl $3500 age $500 Photo Pac $1440 age Scale drawing $625 postage LASER cut parts $16000 postage Landing gear alco legs $21000 Balsa ad spruce material par $6000 p Comolete nackage $51000 0 postaae Best Scale Catalog $700BOB HOLMAN PLANS PO BOX 741 MA New Laser Cut Parts Kits SAN BERNARDINO CA 92402 909-8893959 BHPLANS@AOLCOM ICi Cl Qi Q2 since direction installed very important Capacitor Cl should have lead marked efully solder installed components copper circuit pattern taking care avoid solder bridges across gaps between traces sure use good-quality resincore electronics-grade solder brighten copper traces fine steel wool Scotchbrite pad before starting Advice and/or instruction fellow modeler circuit-assembly experience could useful excess resin left soldering can easily removed solvent such lacquer thinner use K&B Super Poxy thinner since thats what have shop epoxy brush brisfies cut back Input/output leads can obtained cutting servo extension cable appropriate particular radio system half Table 3 summarizes wire color codes typically used some common radio systems Using Figure 3 carefully attach leads according chart Note wires both input output leads attached points B Airtronics users should cautioned V V- wires reversed servo harness Futaba JR RCD radio systems Since Airtronics harness has two wires same color black carefully note denoted center wire Table 3 Installation operation use servo reverser circuit simply plugged between receiver arm y harness servo nice touch achieved sliding finished circuit short length one-inch heat-shrink tubing careful overheat circuit shrinking desired second set output leads can attached points B C resulting built-in Y-harness like wrap finished circuit layer -inch latex foam held couple rubber bands shield against engine vibration answers questions additional information about servo reverser can contacted Internet cbdane@pacbellnet t Dane 678 Crane Ave Livermore CA 94550 Sources Press-n-Peel Electronics Corp Van Nuys CA 91411 818 997-1806 Circuit board Avnilable $10 author Complete kit $15 author 270k resistor SASE author no other charge May1997 41 SUPERFAST LOWDELIVERY PRICES I1-11 IL LCALWAYS MINIATURE BEARINGS FOR HOBBY & INDUSTRY lete Product LinesWe Have Premium UlbaSeal frictionless sealed maintenance-free bearingsthe Largest R/C CarsEeeuePowu bearings engineered strength & durability Tucks, High-Speal hgh heat engne bear ngsInventory BoatsStandard US Metr c s zesand PlanesAsk us about MIDAS TOUCH Other F ne ProductsWidest &Send $3 00 CatalogsSelection Helicopters Deaie P og ama Ava abe BOCA BEARING Co-IN STOCK 7040W Palmetto Park Rd Suite 2304 Ml Boca Raton FL 33433 Tel 407 998 0004 407 908 0110 W USA CANADA CALL TOLL FREE 800-332-3256 DA . .- FOR PRiCtS & INFO FKG MUD DUCK AVIAIION 7118 Westmoreland Dr Worrenton VA 22186 15401 347-1134
Edition: Model Aviation - 1997/05
Page Numbers: 30, 35, 36, 39, 41
An inexpensive circuit size postage stamp reverses direction travel proportional servo Its simple design using commonly available electronic components makes great project RC modeler SERVO REVERSER have kidding would need very oldest RC systems allow modeler reverse direction rotation servo just flip switch case newest transmitters couple simple programming steps Based might conclude need servo reversing gone forever However case Highly maneuverable aerobatic airplanes Extras Sukhois Caps name few becoming increasingly popular competition sport fliers trend larger models more-powerful engines need reliable control-surface actuation critical ever very effective method controlling highly loaded flying surfaces minimize length complexity control linkages mounting servos very near flying surfaces control case split elevators popular practice mount servo directly side fuselage just below horizontal stabilizer Both servos can driven single channel using Y-harness extension cable pushrods attached same side servo arm ie top bottom servo motors must rotate opposite directions same control input receiver Therefore servo needs reversed respect other may tempted mount servos different vertical positions side fuselage pushrods can come off opposite side servos maintaining relatively straight path elevator control horns However since two geometries provide equal elevator throw extremes travel direction acceptable solution result induced twisting moment elevator positions away neutrala serious 30 Model Aviation * Graphic Design Carla Kunz filtered voltage supply V1 RiP2 servo V4 receiver rIrc3 110111 15101 IIP8 04 23 Vt rWr 12FF problem roll-sensitive aerobatic model alternative maintain mirror-image symmetry elevator control installation force servo rotate direction opposite other Both control linkages should come off bottom servo top control split elevators just number situations could require servo reversing Flap actuation throttle control multiengine aircraft other useful examples Y-harness applications several ways approach task reversing servo first physically modify servo reverse its rotation taking servo apart reversing electrical connections motor feedback potentiometer procedure often complicated fact motor can attached directly printed-circuit board motor generally glued case more-expensive ballbearing servos sometimes requiring servo housing broken away replaced second approach could attach servos separate channels programmable computer radio system Using electronic mixing channel could reversed slaved elevator channel seems like great solution indeed will manufacturers radios figure out need type dual servo control However try now will find radio systems am aware transmitter trim lever will affect master servo leaving slave servo unchanged third optionthe solution presented hereis insert electronic device between Y-harness servos would intercept electronic control signals convert necessary drive servo reverse concept inline electronic servo reverser new can purchased number RC manufacturers generally will work pretty well article illustrates important role devices still play RC modeling presents simple inexpensive design can readily built modelers fairly significant shortcoming shared commercially available reversers use onboard centering adjustment usually takes form carbon film potentiometer particularly susceptible temperature drift can cause unwanted changes trim reversed servo ambient temperature changes avoided design Theory Operation understand electronic servo reverser works first necessary review control signals sent receiver servo three wires connecting servo receiver first two supply plus minus voltage battery pack often red black respectively third wire carries pulses direct motion servo positive pulses occur rate about 60 per second vary width between about l-2ms milliseconds thousandths second pulse width lms sends servo output limit rotation direction 2ms limit other reverser circuit based common readily available 555 timer chip Actually 556 version used two independent 555s single 14-pin package Figure 3 shows schematic servo reverser design Figure 4 presents timing diagram useful understanding operates Servo motors tend draw current small gulps lasting 1-2 ms places small ripple receiver battery voltage servo motion particularly noticeable using high-torque ball-bearing servos Although reverser will continue work over wide battery voltage range trim changes rapid voltage fluctuations filtered could occasionally May1997 35 II a Input pulee receiver timer bInverted trigger discharge pulse pin Sdelayed P7 2/3 V1 c Charging signaltimer 2 pins 2 12 I I terminated II II II d Filtered trigger pulse pin 8 timer2 grnet\ aOutput pulse I I s I llxR6sC2 II Figure 1Timing diagram Figure 2 Figure 3 -v receiver ~ servos installed control arms opposite sides servo such shown figures b unequal elevator throw will result order maintain mirror image mechanical symmetry servo must reversed 6 # partsDescriptionPart number# packages 47 resistor271-1 105 310k resistor271-1335 347k resistor271-1342 270k 1% metal film resistorN/A 470pF ceramic disk capacitor272-125 2OlpF PC-mount capacitor272-1065 22pF radial-lead electrolytic capacitor272-1026 2MPS2222A npn transistor276-2009 56 dual timer276-1728 6 ResistorsCapacitors Rl10kbrown black orange*Cl22pF R247kyellow purple blackC20111F** R310kbrown black orangeC301sF R447kyellow purple orangeC4470pF*** R547kyellow purple orange R6270kred purple yellowTransistors R710kbrown black orangeQiMPS2222A R847kyellow purple orangeQ2MPS2222A * The last resistor color band gold 5% resistors ** Ot1iF capacitor labeled 103 F capacitor labeled 471 6 Manufacturer Airtronics JR RCD/Hitec Futaba Positive voltage B black / red red center wire red center wire red center wire Negative voltage black center wire brown black black Signal C D black orange yellow wbite 36 Model Aviation Full-size ImOw ft 2X cause small amount mechanical chatter observed servo output another servo moved addition previously mentioned temperature drift has common complaint associated some commercially available designs Referring schematic shown Figure 2 resistor Ri capacitor Cl transistor Qi form filtered voltage source supplies entire circuit suppresses rapid voltage flutter Resistor R2 acts current limit protect Ql case accidental short circuit What about centering adjustment Most commercial units include feature expense trim settings may vary excessively changing temperature chose use fixed value 270k Q R6 believing provide adjustment would redundant centering method electronic trim mechanical adjustment would have used servo reverser circuit place great advantage fixed setting allows 1% metal film resistor used has very good temperature stability CONSTRUCTION An important goal able build circuit components could easily purchased electronics supply such Radio Shack successful except resistor R6 270k 1% metal film resistor should easily obtained another local electronics supply best way make circuit board product called Press-n-Peel blue plastic film can run through conventional photocopy machine directprinted laser printer image should copied onto dull side film ironed onto copper-clad board Radio Shack 276-1499 using household iron airplane film sealing iron experimenting best temperature found useful securely tape film board along edge could carefully peel back small portion test adhesion pattern board After successful image transfer board etched solution ferric chloride Radio Shack 276-1535 30-60 minutes until unwanted copper gone Note blank board two-sided copper will removed back side board large enough simultaneously make up 20 printed-circuit boards After etching mounting holes should drilled #65 bit easily accomplished since copper surrounding hole location accurately guides drill modelers interested building circuit want manufacture PC board need 270k resistor may contact author Alternatively complete unassembled kit minus servo connectors can obtained components should inserted side opposite copper circuit pattern resistors should mounted vertically Pay special attention May1997 39 THE BEST IN SCALE ELITE PLANS Dennis Bryant Dennis Bryant Englands best scale designers Dennis also top scale builder flyer Dennis has own plan service England Bob Holman has always Dennis agent USA 26 different plans available Accessories available plans Designers like Dennis Bryant will sell plan tilt model has built successfully test flown Feisler Storch 1/6th scale 96 span Power 90-1204 stroke Plans/templates $4000 postage Laser cat main wing ribs $2000 Epoxy glass cowl $3500 age $500 Photo Pac $1440 age Scale drawing $625 postage LASER cut parts $16000 postage Landing gear alco legs $21000 Balsa ad spruce material par $6000 p Comolete nackage $51000 0 postaae Best Scale Catalog $700BOB HOLMAN PLANS PO BOX 741 MA New Laser Cut Parts Kits SAN BERNARDINO CA 92402 909-8893959 BHPLANS@AOLCOM ICi Cl Qi Q2 since direction installed very important Capacitor Cl should have lead marked efully solder installed components copper circuit pattern taking care avoid solder bridges across gaps between traces sure use good-quality resincore electronics-grade solder brighten copper traces fine steel wool Scotchbrite pad before starting Advice and/or instruction fellow modeler circuit-assembly experience could useful excess resin left soldering can easily removed solvent such lacquer thinner use K&B Super Poxy thinner since thats what have shop epoxy brush brisfies cut back Input/output leads can obtained cutting servo extension cable appropriate particular radio system half Table 3 summarizes wire color codes typically used some common radio systems Using Figure 3 carefully attach leads according chart Note wires both input output leads attached points B Airtronics users should cautioned V V- wires reversed servo harness Futaba JR RCD radio systems Since Airtronics harness has two wires same color black carefully note denoted center wire Table 3 Installation operation use servo reverser circuit simply plugged between receiver arm y harness servo nice touch achieved sliding finished circuit short length one-inch heat-shrink tubing careful overheat circuit shrinking desired second set output leads can attached points B C resulting built-in Y-harness like wrap finished circuit layer -inch latex foam held couple rubber bands shield against engine vibration answers questions additional information about servo reverser can contacted Internet cbdane@pacbellnet t Dane 678 Crane Ave Livermore CA 94550 Sources Press-n-Peel Electronics Corp Van Nuys CA 91411 818 997-1806 Circuit board Avnilable $10 author Complete kit $15 author 270k resistor SASE author no other charge May1997 41 SUPERFAST LOWDELIVERY PRICES I1-11 IL LCALWAYS MINIATURE BEARINGS FOR HOBBY & INDUSTRY lete Product LinesWe Have Premium UlbaSeal frictionless sealed maintenance-free bearingsthe Largest R/C CarsEeeuePowu bearings engineered strength & durability Tucks, High-Speal hgh heat engne bear ngsInventory BoatsStandard US Metr c s zesand PlanesAsk us about MIDAS TOUCH Other F ne ProductsWidest &Send $3 00 CatalogsSelection Helicopters Deaie P og ama Ava abe BOCA BEARING Co-IN STOCK 7040W Palmetto Park Rd Suite 2304 Ml Boca Raton FL 33433 Tel 407 998 0004 407 908 0110 W USA CANADA CALL TOLL FREE 800-332-3256 DA . .- FOR PRiCtS & INFO FKG MUD DUCK AVIAIION 7118 Westmoreland Dr Worrenton VA 22186 15401 347-1134
Edition: Model Aviation - 1997/05
Page Numbers: 30, 35, 36, 39, 41
An inexpensive circuit size postage stamp reverses direction travel proportional servo Its simple design using commonly available electronic components makes great project RC modeler SERVO REVERSER have kidding would need very oldest RC systems allow modeler reverse direction rotation servo just flip switch case newest transmitters couple simple programming steps Based might conclude need servo reversing gone forever However case Highly maneuverable aerobatic airplanes Extras Sukhois Caps name few becoming increasingly popular competition sport fliers trend larger models more-powerful engines need reliable control-surface actuation critical ever very effective method controlling highly loaded flying surfaces minimize length complexity control linkages mounting servos very near flying surfaces control case split elevators popular practice mount servo directly side fuselage just below horizontal stabilizer Both servos can driven single channel using Y-harness extension cable pushrods attached same side servo arm ie top bottom servo motors must rotate opposite directions same control input receiver Therefore servo needs reversed respect other may tempted mount servos different vertical positions side fuselage pushrods can come off opposite side servos maintaining relatively straight path elevator control horns However since two geometries provide equal elevator throw extremes travel direction acceptable solution result induced twisting moment elevator positions away neutrala serious 30 Model Aviation * Graphic Design Carla Kunz filtered voltage supply V1 RiP2 servo V4 receiver rIrc3 110111 15101 IIP8 04 23 Vt rWr 12FF problem roll-sensitive aerobatic model alternative maintain mirror-image symmetry elevator control installation force servo rotate direction opposite other Both control linkages should come off bottom servo top control split elevators just number situations could require servo reversing Flap actuation throttle control multiengine aircraft other useful examples Y-harness applications several ways approach task reversing servo first physically modify servo reverse its rotation taking servo apart reversing electrical connections motor feedback potentiometer procedure often complicated fact motor can attached directly printed-circuit board motor generally glued case more-expensive ballbearing servos sometimes requiring servo housing broken away replaced second approach could attach servos separate channels programmable computer radio system Using electronic mixing channel could reversed slaved elevator channel seems like great solution indeed will manufacturers radios figure out need type dual servo control However try now will find radio systems am aware transmitter trim lever will affect master servo leaving slave servo unchanged third optionthe solution presented hereis insert electronic device between Y-harness servos would intercept electronic control signals convert necessary drive servo reverse concept inline electronic servo reverser new can purchased number RC manufacturers generally will work pretty well article illustrates important role devices still play RC modeling presents simple inexpensive design can readily built modelers fairly significant shortcoming shared commercially available reversers use onboard centering adjustment usually takes form carbon film potentiometer particularly susceptible temperature drift can cause unwanted changes trim reversed servo ambient temperature changes avoided design Theory Operation understand electronic servo reverser works first necessary review control signals sent receiver servo three wires connecting servo receiver first two supply plus minus voltage battery pack often red black respectively third wire carries pulses direct motion servo positive pulses occur rate about 60 per second vary width between about l-2ms milliseconds thousandths second pulse width lms sends servo output limit rotation direction 2ms limit other reverser circuit based common readily available 555 timer chip Actually 556 version used two independent 555s single 14-pin package Figure 3 shows schematic servo reverser design Figure 4 presents timing diagram useful understanding operates Servo motors tend draw current small gulps lasting 1-2 ms places small ripple receiver battery voltage servo motion particularly noticeable using high-torque ball-bearing servos Although reverser will continue work over wide battery voltage range trim changes rapid voltage fluctuations filtered could occasionally May1997 35 II a Input pulee receiver timer bInverted trigger discharge pulse pin Sdelayed P7 2/3 V1 c Charging signaltimer 2 pins 2 12 I I terminated II II II d Filtered trigger pulse pin 8 timer2 grnet\ aOutput pulse I I s I llxR6sC2 II Figure 1Timing diagram Figure 2 Figure 3 -v receiver ~ servos installed control arms opposite sides servo such shown figures b unequal elevator throw will result order maintain mirror image mechanical symmetry servo must reversed 6 # partsDescriptionPart number# packages 47 resistor271-1 105 310k resistor271-1335 347k resistor271-1342 270k 1% metal film resistorN/A 470pF ceramic disk capacitor272-125 2OlpF PC-mount capacitor272-1065 22pF radial-lead electrolytic capacitor272-1026 2MPS2222A npn transistor276-2009 56 dual timer276-1728 6 ResistorsCapacitors Rl10kbrown black orange*Cl22pF R247kyellow purple blackC20111F** R310kbrown black orangeC301sF R447kyellow purple orangeC4470pF*** R547kyellow purple orange R6270kred purple yellowTransistors R710kbrown black orangeQiMPS2222A R847kyellow purple orangeQ2MPS2222A * The last resistor color band gold 5% resistors ** Ot1iF capacitor labeled 103 F capacitor labeled 471 6 Manufacturer Airtronics JR RCD/Hitec Futaba Positive voltage B black / red red center wire red center wire red center wire Negative voltage black center wire brown black black Signal C D black orange yellow wbite 36 Model Aviation Full-size ImOw ft 2X cause small amount mechanical chatter observed servo output another servo moved addition previously mentioned temperature drift has common complaint associated some commercially available designs Referring schematic shown Figure 2 resistor Ri capacitor Cl transistor Qi form filtered voltage source supplies entire circuit suppresses rapid voltage flutter Resistor R2 acts current limit protect Ql case accidental short circuit What about centering adjustment Most commercial units include feature expense trim settings may vary excessively changing temperature chose use fixed value 270k Q R6 believing provide adjustment would redundant centering method electronic trim mechanical adjustment would have used servo reverser circuit place great advantage fixed setting allows 1% metal film resistor used has very good temperature stability CONSTRUCTION An important goal able build circuit components could easily purchased electronics supply such Radio Shack successful except resistor R6 270k 1% metal film resistor should easily obtained another local electronics supply best way make circuit board product called Press-n-Peel blue plastic film can run through conventional photocopy machine directprinted laser printer image should copied onto dull side film ironed onto copper-clad board Radio Shack 276-1499 using household iron airplane film sealing iron experimenting best temperature found useful securely tape film board along edge could carefully peel back small portion test adhesion pattern board After successful image transfer board etched solution ferric chloride Radio Shack 276-1535 30-60 minutes until unwanted copper gone Note blank board two-sided copper will removed back side board large enough simultaneously make up 20 printed-circuit boards After etching mounting holes should drilled #65 bit easily accomplished since copper surrounding hole location accurately guides drill modelers interested building circuit want manufacture PC board need 270k resistor may contact author Alternatively complete unassembled kit minus servo connectors can obtained components should inserted side opposite copper circuit pattern resistors should mounted vertically Pay special attention May1997 39 THE BEST IN SCALE ELITE PLANS Dennis Bryant Dennis Bryant Englands best scale designers Dennis also top scale builder flyer Dennis has own plan service England Bob Holman has always Dennis agent USA 26 different plans available Accessories available plans Designers like Dennis Bryant will sell plan tilt model has built successfully test flown Feisler Storch 1/6th scale 96 span Power 90-1204 stroke Plans/templates $4000 postage Laser cat main wing ribs $2000 Epoxy glass cowl $3500 age $500 Photo Pac $1440 age Scale drawing $625 postage LASER cut parts $16000 postage Landing gear alco legs $21000 Balsa ad spruce material par $6000 p Comolete nackage $51000 0 postaae Best Scale Catalog $700BOB HOLMAN PLANS PO BOX 741 MA New Laser Cut Parts Kits SAN BERNARDINO CA 92402 909-8893959 BHPLANS@AOLCOM ICi Cl Qi Q2 since direction installed very important Capacitor Cl should have lead marked efully solder installed components copper circuit pattern taking care avoid solder bridges across gaps between traces sure use good-quality resincore electronics-grade solder brighten copper traces fine steel wool Scotchbrite pad before starting Advice and/or instruction fellow modeler circuit-assembly experience could useful excess resin left soldering can easily removed solvent such lacquer thinner use K&B Super Poxy thinner since thats what have shop epoxy brush brisfies cut back Input/output leads can obtained cutting servo extension cable appropriate particular radio system half Table 3 summarizes wire color codes typically used some common radio systems Using Figure 3 carefully attach leads according chart Note wires both input output leads attached points B Airtronics users should cautioned V V- wires reversed servo harness Futaba JR RCD radio systems Since Airtronics harness has two wires same color black carefully note denoted center wire Table 3 Installation operation use servo reverser circuit simply plugged between receiver arm y harness servo nice touch achieved sliding finished circuit short length one-inch heat-shrink tubing careful overheat circuit shrinking desired second set output leads can attached points B C resulting built-in Y-harness like wrap finished circuit layer -inch latex foam held couple rubber bands shield against engine vibration answers questions additional information about servo reverser can contacted Internet cbdane@pacbellnet t Dane 678 Crane Ave Livermore CA 94550 Sources Press-n-Peel Electronics Corp Van Nuys CA 91411 818 997-1806 Circuit board Avnilable $10 author Complete kit $15 author 270k resistor SASE author no other charge May1997 41 SUPERFAST LOWDELIVERY PRICES I1-11 IL LCALWAYS MINIATURE BEARINGS FOR HOBBY & INDUSTRY lete Product LinesWe Have Premium UlbaSeal frictionless sealed maintenance-free bearingsthe Largest R/C CarsEeeuePowu bearings engineered strength & durability Tucks, High-Speal hgh heat engne bear ngsInventory BoatsStandard US Metr c s zesand PlanesAsk us about MIDAS TOUCH Other F ne ProductsWidest &Send $3 00 CatalogsSelection Helicopters Deaie P og ama Ava abe BOCA BEARING Co-IN STOCK 7040W Palmetto Park Rd Suite 2304 Ml Boca Raton FL 33433 Tel 407 998 0004 407 908 0110 W USA CANADA CALL TOLL FREE 800-332-3256 DA . .- FOR PRiCtS & INFO FKG MUD DUCK AVIAIION 7118 Westmoreland Dr Worrenton VA 22186 15401 347-1134