Something About Switches Some time ago friend called problem agreed look did seemed problem traceable high resistance switch Before could tell him such resistances usually measured l/lOOOths ohm would invisible multitestor started probing around circuit said AHA youre right showed 30 ohms across points goldplated 6-pole 24-contact stepping switch So kept mouth shut smiled. after theres no point arguing guy whos telling you genius other hand shows what little dirt grime can keeps getting too cocky Switches RC systems seldom gold-plated makes little likely have contact resistance problems common causes switch problems dirt corrosion mechanical damage Any will cause radio problems some things can protect yourself against may times have flying field heard awful thud another model screwing itself ground Did notice during post-mortum examination someone worked switch back forth few times suddenly radio system working fine again Chances plane crashed because switch dirty corroded did get way Silver-plated switches form tough adherent black coating sulphides air Working switch back forth will scrub off coating tiny area makes electrical contact turn switch off fly chances excellent will scrub off part result increase current such moving two servos simultaneously will cause excessive voltage drop across switch contacts leads momentary loss control happens right time loss altitude results can excessive rule calculating stated 1826 German philosopher Georg Simon Ohm followsI _ E R ent measured amperes F age direct current R stance measured ohms assume battery pack shows open circuit voltage 50 volts trouble will start drops 44 volts necessarily true par ticular radio generally correct voltage drop 06 volts switch will job Usually 4-channel system will draw about 1/10 ampere 100 ma turned doing nothing divided 20 ma apiece servo receiver Under load servo can draw much 450 ma Lets assume two servos drawing full current Technique George NL Myers total current 960 ma 096 amperes rearranging equation suit problem have R F — O62Sohms 096 tells us less ohm resistance can give us glitch some liquid tarnish removers available advertized TV might tempted use clean switches Dont leave film washed off promptly makes things worse Either work tarnish off exercis ing switch battery discon nected use good tuner cleaner can purchased local electronics store Another type switch contamination comes engine Raw fuel partic ularly high-nitro types can very corrosive burned fuel can very sticky good idea mount switch side fuselage opposite exhaust mount inside fuselage work rod sticks out side fuselage opposite exhaust Periodic cleaning wood alcohol tape recorder head cleaner helps get rid castor oil may accumulate Mechanical damage kind can loosen contacts subtle kinds damage occurs need longer #3-48 screw mount switch because fuselage side thicker usual Unless careful longer screw can too long will push switch assembly right off back metal body Since happens inside plane its frequently overlooked until something fails feel little profit repairing damaged switches Replace leads consideration various switch configurations might use Fig 1 through 3 show some typical configurations gives some considerations characteristics particular want consider bene fits come paralleling two contacts provide function Ohms law parallel resistances states SIMPLEST LIGHTEST MOST LIKELY TO BATTERYCHARGINGRECEIVERHAVE CONTACT RESISTANCE PROBLEMS POSSIBILITY OF CHARGER FEEDING OPERATING RECEIVER FIGURE 1 SPST NO SIGNIFICANT ADVANTAGE OVER FIGURE 1 EXCEPT BATTERYCHARGING IRECEIVERRECEIVER MNLBE ISOLATED FROM THE CHARGER FIGURE 2 DPST BATTERYCHARGINGRECEIVER PACKIJACK FIGURE 3 4PDT LARGER HEAVIER MORE COMPLICATED LEAST SUSCEPTIBLE TO CONTACT RESISTANCE PROBLEMS CHARGER CANNOT BE CONNECTED TO OPERATING RECEIVER June1976 9 Radio Technique 1111 Rtotal Rn practical significance two switch contacts parallel will exhibit one-half resistance either equal contact develops significant resistance some reason other doesnt resistance parallel pair will still less resistance good contact Look equation think about havent already belive Fig 3 used some biggest RC manufacturers best way go spite size weight Clean inspect switch assembly frequently insure trouble-free flying Look signs contamination corro sion damage cant make simple repairs throw thing away wont tempted use emergency Pay particular attention wires point enter switch plugs looking broken wires soft spots often conceal wires have broken inside insula tion protect switch assembly will protect plane Please send ideas would like see discussed address below wish personal reply include stamped self-addressed envelope believe Bill Cannon well-known manufacturer tiny radio systems latest offering hobby 4channel airborne system weighs 45 ounces can long pleasant discussion Mr Cannon WRAMS Show Westchester Aero Modelers Inc White Plains NY 28 & 29 Feb 76 nut shell did extreme attention detail searching world over right components system display see Bills Mini fighter 18-ounce tricycle-gear air plane powered Cox TD 049 modi fied addition exhaust baffle OS 10 throttle featured rudder/nosewheel steering ailerons ele vators throttle see photo heaviest unit airborne system battery pack Mr Cannon got spe cial l00-maH fast-charge batteries General Electric cut battery pack weight 1 ounce pack will give about 20 minutes flying per charge can recharged field 10 minutes connecting 6-volt lantern battery Next list weight items usually servo motor 12-millimeter motor used place usual 16-mm size can tell literally jewel German product has one-third volume weight usual motor costs bit used paying price settled time projected price complete servo housed new smaller plastic case weighs 7/10 ounce $5 standard servo Deans connectors used servo can used other systems can make repairs easily think scale model builders will find kinds new places hide tiny servo hasnt got power larger servos Cannon recommends used 010 10 powered models can use larger servos primary flight controls save weight space secondaries like bomb bay doors sliding canopies etc Within servo case evolu tionary servo-amplifier uses im proved Signetics IC save weight space parts count has mini mized /8-watt resistors miniature tantalum capacitors used inter connecting wires copper heavy friends 29 gauge/53 strand construction work fits case measures 19/32 x 1-7/32 x 1-7/32 Bill tieclip didnt look out place examined receiver found single-deck construc tion looked very much like former receiver except shrunken Notable fea tures include special crystal case about /4 size used seeing special transisters Hong Kong nearly invisible under magnifying glass used addi tion reading glasses fly glasses its eyes things small really dont think people will fixing own sets Two normal FET three normal 7 mm IF cans look strangely out place board Mr Cannon says cant get performance need smaller ones more-or-less usual DIPpackaged decoder fills opposite edge board rest space filled Vs-watt resisters tantalum capacitors servo-amplifier soldering has done hand very patient people Technically circuit described double-tuned FET receiver dual AGC 8-bit shift-register decoder Therefore can have sys tem wired up eight servos use favorite multi-channel trans mitter system leads consider things like indoor RC return free-flight models small fields like Old Timer Bash Joe Beshars RC-assisted FreeFlight meet Lakehurst NJ May 16 1976 whole new generation cheaper small durable trainer models Anyone flies racers knows good easier fly well good pattern airplane its gas-guzzling Schneurle 60 Therefore 049 trainers should make better fliers sooner bewildering array options being offered Cannons new 45 ounce air borne package full details options prices deliveries contact dealer write Cannon Electronics 13400-26 Saticoy St North Hollywood CA 91605 part column intended report significant trends products RC field Information gathered interviewing people AMA policy authors allowed accept pro ducts own use unless purchased prevailing market prices know material suitable presentation news story format please contact address below well share members address 70 Froeblich Farm Rd Hicksville NY 11801 10 ModelAviation Mini-fighter 1/2A full-house model exhibited WRAMS Show Bill Cannon outdid himself making things smaller lighter beforeand took some doing methods accomplished superb miniaturization described text based upon technical talk-fest between author Bill 4-channel set weighs 46 oz
Edition: Model Aviation - 1976/06
Page Numbers: 9, 10
Something About Switches Some time ago friend called problem agreed look did seemed problem traceable high resistance switch Before could tell him such resistances usually measured l/lOOOths ohm would invisible multitestor started probing around circuit said AHA youre right showed 30 ohms across points goldplated 6-pole 24-contact stepping switch So kept mouth shut smiled. after theres no point arguing guy whos telling you genius other hand shows what little dirt grime can keeps getting too cocky Switches RC systems seldom gold-plated makes little likely have contact resistance problems common causes switch problems dirt corrosion mechanical damage Any will cause radio problems some things can protect yourself against may times have flying field heard awful thud another model screwing itself ground Did notice during post-mortum examination someone worked switch back forth few times suddenly radio system working fine again Chances plane crashed because switch dirty corroded did get way Silver-plated switches form tough adherent black coating sulphides air Working switch back forth will scrub off coating tiny area makes electrical contact turn switch off fly chances excellent will scrub off part result increase current such moving two servos simultaneously will cause excessive voltage drop across switch contacts leads momentary loss control happens right time loss altitude results can excessive rule calculating stated 1826 German philosopher Georg Simon Ohm followsI _ E R ent measured amperes F age direct current R stance measured ohms assume battery pack shows open circuit voltage 50 volts trouble will start drops 44 volts necessarily true par ticular radio generally correct voltage drop 06 volts switch will job Usually 4-channel system will draw about 1/10 ampere 100 ma turned doing nothing divided 20 ma apiece servo receiver Under load servo can draw much 450 ma Lets assume two servos drawing full current Technique George NL Myers total current 960 ma 096 amperes rearranging equation suit problem have R F — O62Sohms 096 tells us less ohm resistance can give us glitch some liquid tarnish removers available advertized TV might tempted use clean switches Dont leave film washed off promptly makes things worse Either work tarnish off exercis ing switch battery discon nected use good tuner cleaner can purchased local electronics store Another type switch contamination comes engine Raw fuel partic ularly high-nitro types can very corrosive burned fuel can very sticky good idea mount switch side fuselage opposite exhaust mount inside fuselage work rod sticks out side fuselage opposite exhaust Periodic cleaning wood alcohol tape recorder head cleaner helps get rid castor oil may accumulate Mechanical damage kind can loosen contacts subtle kinds damage occurs need longer #3-48 screw mount switch because fuselage side thicker usual Unless careful longer screw can too long will push switch assembly right off back metal body Since happens inside plane its frequently overlooked until something fails feel little profit repairing damaged switches Replace leads consideration various switch configurations might use Fig 1 through 3 show some typical configurations gives some considerations characteristics particular want consider bene fits come paralleling two contacts provide function Ohms law parallel resistances states SIMPLEST LIGHTEST MOST LIKELY TO BATTERYCHARGINGRECEIVERHAVE CONTACT RESISTANCE PROBLEMS POSSIBILITY OF CHARGER FEEDING OPERATING RECEIVER FIGURE 1 SPST NO SIGNIFICANT ADVANTAGE OVER FIGURE 1 EXCEPT BATTERYCHARGING IRECEIVERRECEIVER MNLBE ISOLATED FROM THE CHARGER FIGURE 2 DPST BATTERYCHARGINGRECEIVER PACKIJACK FIGURE 3 4PDT LARGER HEAVIER MORE COMPLICATED LEAST SUSCEPTIBLE TO CONTACT RESISTANCE PROBLEMS CHARGER CANNOT BE CONNECTED TO OPERATING RECEIVER June1976 9 Radio Technique 1111 Rtotal Rn practical significance two switch contacts parallel will exhibit one-half resistance either equal contact develops significant resistance some reason other doesnt resistance parallel pair will still less resistance good contact Look equation think about havent already belive Fig 3 used some biggest RC manufacturers best way go spite size weight Clean inspect switch assembly frequently insure trouble-free flying Look signs contamination corro sion damage cant make simple repairs throw thing away wont tempted use emergency Pay particular attention wires point enter switch plugs looking broken wires soft spots often conceal wires have broken inside insula tion protect switch assembly will protect plane Please send ideas would like see discussed address below wish personal reply include stamped self-addressed envelope believe Bill Cannon well-known manufacturer tiny radio systems latest offering hobby 4channel airborne system weighs 45 ounces can long pleasant discussion Mr Cannon WRAMS Show Westchester Aero Modelers Inc White Plains NY 28 & 29 Feb 76 nut shell did extreme attention detail searching world over right components system display see Bills Mini fighter 18-ounce tricycle-gear air plane powered Cox TD 049 modi fied addition exhaust baffle OS 10 throttle featured rudder/nosewheel steering ailerons ele vators throttle see photo heaviest unit airborne system battery pack Mr Cannon got spe cial l00-maH fast-charge batteries General Electric cut battery pack weight 1 ounce pack will give about 20 minutes flying per charge can recharged field 10 minutes connecting 6-volt lantern battery Next list weight items usually servo motor 12-millimeter motor used place usual 16-mm size can tell literally jewel German product has one-third volume weight usual motor costs bit used paying price settled time projected price complete servo housed new smaller plastic case weighs 7/10 ounce $5 standard servo Deans connectors used servo can used other systems can make repairs easily think scale model builders will find kinds new places hide tiny servo hasnt got power larger servos Cannon recommends used 010 10 powered models can use larger servos primary flight controls save weight space secondaries like bomb bay doors sliding canopies etc Within servo case evolu tionary servo-amplifier uses im proved Signetics IC save weight space parts count has mini mized /8-watt resistors miniature tantalum capacitors used inter connecting wires copper heavy friends 29 gauge/53 strand construction work fits case measures 19/32 x 1-7/32 x 1-7/32 Bill tieclip didnt look out place examined receiver found single-deck construc tion looked very much like former receiver except shrunken Notable fea tures include special crystal case about /4 size used seeing special transisters Hong Kong nearly invisible under magnifying glass used addi tion reading glasses fly glasses its eyes things small really dont think people will fixing own sets Two normal FET three normal 7 mm IF cans look strangely out place board Mr Cannon says cant get performance need smaller ones more-or-less usual DIPpackaged decoder fills opposite edge board rest space filled Vs-watt resisters tantalum capacitors servo-amplifier soldering has done hand very patient people Technically circuit described double-tuned FET receiver dual AGC 8-bit shift-register decoder Therefore can have sys tem wired up eight servos use favorite multi-channel trans mitter system leads consider things like indoor RC return free-flight models small fields like Old Timer Bash Joe Beshars RC-assisted FreeFlight meet Lakehurst NJ May 16 1976 whole new generation cheaper small durable trainer models Anyone flies racers knows good easier fly well good pattern airplane its gas-guzzling Schneurle 60 Therefore 049 trainers should make better fliers sooner bewildering array options being offered Cannons new 45 ounce air borne package full details options prices deliveries contact dealer write Cannon Electronics 13400-26 Saticoy St North Hollywood CA 91605 part column intended report significant trends products RC field Information gathered interviewing people AMA policy authors allowed accept pro ducts own use unless purchased prevailing market prices know material suitable presentation news story format please contact address below well share members address 70 Froeblich Farm Rd Hicksville NY 11801 10 ModelAviation Mini-fighter 1/2A full-house model exhibited WRAMS Show Bill Cannon outdid himself making things smaller lighter beforeand took some doing methods accomplished superb miniaturization described text based upon technical talk-fest between author Bill 4-channel set weighs 46 oz