I HAVE FOUND servo tester handiest gadgets RC modeler can have workbench may used example installing servos new model need use rest airborne pack set up travel also useful providing signal source servicing servos provides neutral standard align servos after servicing several servo testers available market several magazines have published articles constructing different designs some extremely complicated circuit have used outstandingly simple uses seven components basic circuit practically guarantees will work components low cost critical size tolerance can easily add basic unit create custom unit features such meters deadband check pre-set neutral limits like However article aimed keeping simple modifi cations up individual Fig 1 presents schematic diagram unit circuit consists two re triggerable one-shot stages con tained integrated circuit SN74123 SN54 123 One-half IC generates clock pulse timed 47k-ohms resistor 10-mfd capacitor repetition frame rate around 20 milliseconds frame pulse coupled second stage trigger variablewidth control pulse stage timed RC network consisting 10k po tentiometer fixed resistor 22k ohms l-mfd capacitor will generate pulse width 05 25 milli seconds depending potentiometer setting part circuit may need alignment after final assembly suit particular system allow component tolerances output second stage fed back trigger input first stage reinitiate cycle IC output stage has signals both polarities available types servos FIGURE 1 available market today TTL output similar modem decoders Note large value capacitor across battery supply must large e can obtainit serves stabi lize supply IC IC SERVO TESTER DESIGNED BY PETER T WATERS -I PC hUSKSten 5LbCIOKI 01-I J hack 47K 1 IOnf 5 8 go II Onf 1146 I13 16 4 isles 1 The cuiScIlS Inarhefl ld hO El least 250511 large lie helter L os/all lIPS jpo Sr InegtNIPilitily Select spIlls JO 48 Iallerg Ta 55 tO S 2 hSiusl valUe ml # reSIstof II Ill psI soIl 155 Ii Increase tIN Ii clockwise 20 Model Aviation complete servo testernote polarized connectors Stock bakelite case may pur chased electronic gadget shops Assembly If have means produce printed circuit board preferred construction Make Kodalith tive full size PC layout Fig 2 etch hoard drill holes number 60 drill other method use insu lated perforated board hard-wire components can follow printed circuit layout components positions Fig 3Note potenti ometer version can assembled through board printed circuit version has potentiometer soldered directly onto copper lands Look care fully integrated circuit insert board its ident tab dot shown used socket integrated circuit perf-board assembly makes soldering easier capaci tors must connected correct polarityturn page Left Printed Circuit side board com ponent side next page Below Component side board potentiometer serves mount Bottom Printed circuit side component boerd appears finished Apriil976 21 FIGURE 2 Simple Servo Tester Clean off flux residue board using lacquer thinner dope thinner small stiff brush toothbrush does nicely Mop off surplus tissue Look over soldered connections touch up necessary Make connect ing wires about 10 inches long De-Luxe version has Polarity Select switch double-pole on-off switch OS Pro-Line older EK units some older World Engine servos ones know use negative pulse Polarity Select switch can eliminated need change po larity signal Install suitable connectors battery pack servo output connections have several different types servos need different connectors either make up adapter cables wire several servo output lines parallel Exercise care handling bare plugs using unit system uses modern threewire type amplifiers eliminate white wire used center-tapped sup ply Check over assembly carefully errors Calibration smoke-test finished unit Set potentiometer middle its rotation set polarity switch appropriately test servo Connect battery turn switch have servo plugged yet Lay finger integrated circuit detect IC becoming warm switch Off look over unit again possible shorts orientation inte grated circuit battery reversed like Assuming well switch Off plug servo Now switch again servo will probably seek position stop Check see can driven both di rections within limits potentiometer travel travel limitation 22k resistor will have changed follows find enough potentiometer rotation clockwise direction increase value resistor 39k ohms Alternatively should potentiometer limit way counter clockwise direction decrease resistor 1k ohms reason relatively wide tolerance values 1 -mfd capacitor Finally rotate potentiometer servo output arm neutral lock knob pointer aligned neutral mark panel wish can also mark panel servo extremes travel thus able check servo travel limits Parts List 1 Dual shot integrated circuit SN74123 5N54123 1 Linear potentiometer 10K ohms 1 Resistor 47K ohms Resistor 22K ohms 1 Capacitor luf least 6 volt 1 Capacitor lOuf least 6 volt 1 Capacitor 250 uf larger least 6 volt 1 Printed Circuit Board Perf Board 1 DPST Switch SPDT Switch 1 Box suit 1 Pointer Knob Misc wire connectors 22 Model Aviation IQI Li 22K lOmf down Blacks 4 SohtSSceflteo tip yellow)\7 10K pot / \ Reds45oBlo10mW down SERVO TESTER OVERLAYFIGURE 3
Edition: Model Aviation - 1976/04
Page Numbers: 20, 21, 22
I HAVE FOUND servo tester handiest gadgets RC modeler can have workbench may used example installing servos new model need use rest airborne pack set up travel also useful providing signal source servicing servos provides neutral standard align servos after servicing several servo testers available market several magazines have published articles constructing different designs some extremely complicated circuit have used outstandingly simple uses seven components basic circuit practically guarantees will work components low cost critical size tolerance can easily add basic unit create custom unit features such meters deadband check pre-set neutral limits like However article aimed keeping simple modifi cations up individual Fig 1 presents schematic diagram unit circuit consists two re triggerable one-shot stages con tained integrated circuit SN74123 SN54 123 One-half IC generates clock pulse timed 47k-ohms resistor 10-mfd capacitor repetition frame rate around 20 milliseconds frame pulse coupled second stage trigger variablewidth control pulse stage timed RC network consisting 10k po tentiometer fixed resistor 22k ohms l-mfd capacitor will generate pulse width 05 25 milli seconds depending potentiometer setting part circuit may need alignment after final assembly suit particular system allow component tolerances output second stage fed back trigger input first stage reinitiate cycle IC output stage has signals both polarities available types servos FIGURE 1 available market today TTL output similar modem decoders Note large value capacitor across battery supply must large e can obtainit serves stabi lize supply IC IC SERVO TESTER DESIGNED BY PETER T WATERS -I PC hUSKSten 5LbCIOKI 01-I J hack 47K 1 IOnf 5 8 go II Onf 1146 I13 16 4 isles 1 The cuiScIlS Inarhefl ld hO El least 250511 large lie helter L os/all lIPS jpo Sr InegtNIPilitily Select spIlls JO 48 Iallerg Ta 55 tO S 2 hSiusl valUe ml # reSIstof II Ill psI soIl 155 Ii Increase tIN Ii clockwise 20 Model Aviation complete servo testernote polarized connectors Stock bakelite case may pur chased electronic gadget shops Assembly If have means produce printed circuit board preferred construction Make Kodalith tive full size PC layout Fig 2 etch hoard drill holes number 60 drill other method use insu lated perforated board hard-wire components can follow printed circuit layout components positions Fig 3Note potenti ometer version can assembled through board printed circuit version has potentiometer soldered directly onto copper lands Look care fully integrated circuit insert board its ident tab dot shown used socket integrated circuit perf-board assembly makes soldering easier capaci tors must connected correct polarityturn page Left Printed Circuit side board com ponent side next page Below Component side board potentiometer serves mount Bottom Printed circuit side component boerd appears finished Apriil976 21 FIGURE 2 Simple Servo Tester Clean off flux residue board using lacquer thinner dope thinner small stiff brush toothbrush does nicely Mop off surplus tissue Look over soldered connections touch up necessary Make connect ing wires about 10 inches long De-Luxe version has Polarity Select switch double-pole on-off switch OS Pro-Line older EK units some older World Engine servos ones know use negative pulse Polarity Select switch can eliminated need change po larity signal Install suitable connectors battery pack servo output connections have several different types servos need different connectors either make up adapter cables wire several servo output lines parallel Exercise care handling bare plugs using unit system uses modern threewire type amplifiers eliminate white wire used center-tapped sup ply Check over assembly carefully errors Calibration smoke-test finished unit Set potentiometer middle its rotation set polarity switch appropriately test servo Connect battery turn switch have servo plugged yet Lay finger integrated circuit detect IC becoming warm switch Off look over unit again possible shorts orientation inte grated circuit battery reversed like Assuming well switch Off plug servo Now switch again servo will probably seek position stop Check see can driven both di rections within limits potentiometer travel travel limitation 22k resistor will have changed follows find enough potentiometer rotation clockwise direction increase value resistor 39k ohms Alternatively should potentiometer limit way counter clockwise direction decrease resistor 1k ohms reason relatively wide tolerance values 1 -mfd capacitor Finally rotate potentiometer servo output arm neutral lock knob pointer aligned neutral mark panel wish can also mark panel servo extremes travel thus able check servo travel limits Parts List 1 Dual shot integrated circuit SN74123 5N54123 1 Linear potentiometer 10K ohms 1 Resistor 47K ohms Resistor 22K ohms 1 Capacitor luf least 6 volt 1 Capacitor lOuf least 6 volt 1 Capacitor 250 uf larger least 6 volt 1 Printed Circuit Board Perf Board 1 DPST Switch SPDT Switch 1 Box suit 1 Pointer Knob Misc wire connectors 22 Model Aviation IQI Li 22K lOmf down Blacks 4 SohtSSceflteo tip yellow)\7 10K pot / \ Reds45oBlo10mW down SERVO TESTER OVERLAYFIGURE 3
Edition: Model Aviation - 1976/04
Page Numbers: 20, 21, 22
I HAVE FOUND servo tester handiest gadgets RC modeler can have workbench may used example installing servos new model need use rest airborne pack set up travel also useful providing signal source servicing servos provides neutral standard align servos after servicing several servo testers available market several magazines have published articles constructing different designs some extremely complicated circuit have used outstandingly simple uses seven components basic circuit practically guarantees will work components low cost critical size tolerance can easily add basic unit create custom unit features such meters deadband check pre-set neutral limits like However article aimed keeping simple modifi cations up individual Fig 1 presents schematic diagram unit circuit consists two re triggerable one-shot stages con tained integrated circuit SN74123 SN54 123 One-half IC generates clock pulse timed 47k-ohms resistor 10-mfd capacitor repetition frame rate around 20 milliseconds frame pulse coupled second stage trigger variablewidth control pulse stage timed RC network consisting 10k po tentiometer fixed resistor 22k ohms l-mfd capacitor will generate pulse width 05 25 milli seconds depending potentiometer setting part circuit may need alignment after final assembly suit particular system allow component tolerances output second stage fed back trigger input first stage reinitiate cycle IC output stage has signals both polarities available types servos FIGURE 1 available market today TTL output similar modem decoders Note large value capacitor across battery supply must large e can obtainit serves stabi lize supply IC IC SERVO TESTER DESIGNED BY PETER T WATERS -I PC hUSKSten 5LbCIOKI 01-I J hack 47K 1 IOnf 5 8 go II Onf 1146 I13 16 4 isles 1 The cuiScIlS Inarhefl ld hO El least 250511 large lie helter L os/all lIPS jpo Sr InegtNIPilitily Select spIlls JO 48 Iallerg Ta 55 tO S 2 hSiusl valUe ml # reSIstof II Ill psI soIl 155 Ii Increase tIN Ii clockwise 20 Model Aviation complete servo testernote polarized connectors Stock bakelite case may pur chased electronic gadget shops Assembly If have means produce printed circuit board preferred construction Make Kodalith tive full size PC layout Fig 2 etch hoard drill holes number 60 drill other method use insu lated perforated board hard-wire components can follow printed circuit layout components positions Fig 3Note potenti ometer version can assembled through board printed circuit version has potentiometer soldered directly onto copper lands Look care fully integrated circuit insert board its ident tab dot shown used socket integrated circuit perf-board assembly makes soldering easier capaci tors must connected correct polarityturn page Left Printed Circuit side board com ponent side next page Below Component side board potentiometer serves mount Bottom Printed circuit side component boerd appears finished Apriil976 21 FIGURE 2 Simple Servo Tester Clean off flux residue board using lacquer thinner dope thinner small stiff brush toothbrush does nicely Mop off surplus tissue Look over soldered connections touch up necessary Make connect ing wires about 10 inches long De-Luxe version has Polarity Select switch double-pole on-off switch OS Pro-Line older EK units some older World Engine servos ones know use negative pulse Polarity Select switch can eliminated need change po larity signal Install suitable connectors battery pack servo output connections have several different types servos need different connectors either make up adapter cables wire several servo output lines parallel Exercise care handling bare plugs using unit system uses modern threewire type amplifiers eliminate white wire used center-tapped sup ply Check over assembly carefully errors Calibration smoke-test finished unit Set potentiometer middle its rotation set polarity switch appropriately test servo Connect battery turn switch have servo plugged yet Lay finger integrated circuit detect IC becoming warm switch Off look over unit again possible shorts orientation inte grated circuit battery reversed like Assuming well switch Off plug servo Now switch again servo will probably seek position stop Check see can driven both di rections within limits potentiometer travel travel limitation 22k resistor will have changed follows find enough potentiometer rotation clockwise direction increase value resistor 39k ohms Alternatively should potentiometer limit way counter clockwise direction decrease resistor 1k ohms reason relatively wide tolerance values 1 -mfd capacitor Finally rotate potentiometer servo output arm neutral lock knob pointer aligned neutral mark panel wish can also mark panel servo extremes travel thus able check servo travel limits Parts List 1 Dual shot integrated circuit SN74123 5N54123 1 Linear potentiometer 10K ohms 1 Resistor 47K ohms Resistor 22K ohms 1 Capacitor luf least 6 volt 1 Capacitor lOuf least 6 volt 1 Capacitor 250 uf larger least 6 volt 1 Printed Circuit Board Perf Board 1 DPST Switch SPDT Switch 1 Box suit 1 Pointer Knob Misc wire connectors 22 Model Aviation IQI Li 22K lOmf down Blacks 4 SohtSSceflteo tip yellow)\7 10K pot / \ Reds45oBlo10mW down SERVO TESTER OVERLAYFIGURE 3