Sound-Level Meters Since have soliciting suggestions column subjects have received several requesting simple circuit sound-level meter Most often thing prompts request concern engine noise following extract letters typical ke clubs today South Jersey Flyaways involved noise problems use infre quently available Db meter have able assemble some information various engine/muffler combinations point have reached con crete position what allowable club flying site assume muffler committee will come out near future recommendation allowable noise levels rub availability Db meter. Would have knowledge available circuit diagram could use construct noise-measuring device own9 Charles Kline 7 Meadowlark Rd Stratford NY its essentials sound-level meter consists four single elements Fig 1 microphone amplifier need expensive signal conditioning can done resistors capacitors display usually meter 1milliamp DC meter will suffice because Db scale can drawn over 0- 1-ma scale using table Fig 2 fact practically VTVM VOM has Db scale will 10-minute recess class checks meters order measure sound levels need assemble necessary components calibrate difficulty starts calibrator usually costs sound-level meter Allied Electronics 1976 Engineering Manual & Purchasing Guide No 760 401 East 8th St Fort Worth TX 76102 still lists low-cost Realistic sound level meter Stock No 910-4028 Type 331028 $4995 formerly carried Radio Shack stores recom mendation interested clubs ob tain will certainly spend money assembling calibrating thing build circuit dia gram want cheaper ap proach have alternative tape recorders have VU meter Volume Units Db indicate recording level have such recorder portable can use Comparative soundlevel meter necessary place recorder some convenient distance engine being tested say 10 ft away put recorder Record mode microphone built-in will have plug appropriate socket Now adjust Vol ume control until meter indicates 0 VU referee engine running referee engine com mittee has decided acceptable Next install other engine same loca tion run VU meter will indicate whether louder VU quieter Geoige Myers MICROPHONEAMPLIFIERSIGNALDISPLAY CONDITIONER FIGURE 1 TIONAL DIAGRAM OF SOUND-LEVEL METER V Db og 20 Log V0 VorA007 22 40 50 56 64 7180 90 100 Db 20 10 5 3 2 1012 3 1 Db lest audible change loudness 6 Db e loud FIGURE 2 SFER FROM LINEAR VOLTAGE OR CURRENT SCALE TO DECIBELS VU referee engine thats really wanted know wont need run magnetic recording tape through machine making measurements unless want record what done As Test Engineer some 20 years experience have decided will always record available data test because data costs less duplicating test setup dont have reduce data until need After measurements completed will discover dont mean much Noise subjective phenomenon barking dog comforting sound its dog youve recently heard burglar-type noises night neighbor its something quite annoy ing Just yesterday talking flying buddy accosted neighbor complained about noise made flying sailplane seems too much running about shouting back forth point am sure still some folks unsatisfied just want build sound-level meter OK Read Tab Books Blue Ridge Summit PA 17214 has just published book Robert P Haviland entitled Build Book Miniature Test Measure ment Instruments $495 Chapter 12 tells build calibrate own sound-level meter package about size Heath Thumb-Tac First Edition First Printing January 1976 local electronics supply house bookstore should have now Its new up-to-date well-written should have no trouble producing useable instru ments instructions given Cali bration another matter think section calibrating sound-level meter will rewritten next edition may permitted moment soap-box Id like say noise prob lems will yield quickly applica tions common sense courtesy other treatment Mufflers avail able convert distasteful snarl crackle engines something like loud hum absolutely no reason us tolerate person refuses use Talk him reason him discipline him within club possible else fails accidently step model Just keep him ground sound broadcast engine travels much further comes flying airplane does ground Limit flying sensible hours determined type neighborhood Avoid flying over homes roads groups people because noise complaints start fear airplane over head will come crashing down arent much position assure anyone cant happen wont need sound-level meters End oratory Recently given copy report submitted AMA Frequency Com mittee FCC entitled results Field Tests Airborne Thermal Sensors Two-Meter Amateur Radio Band dated March 15 1976 have no intention reprinting think credit AMA such well-planned executed documented series tests have conducted 10 Model Aviation name AMA may recognize some participants names have abstracted acknowledge ments W Tynan W3KMV J Colson W3TMZ W Good W3NPS J Strong WN3YJA J Hamblen W3TZ D Clark W3YSC D Goughnour W3RVX D Frey K3AAX R Robin son WA3YEE R Givens T Holder R McNeil Apparently FCC requested report after exhibiting some concern effect RF transmissions Thermal Sensors carried RC sailplanes Briefly tests examined effects Thermal Sensor emissions upon signals 2-meter repeater stations both put output upon signals Oscar 7 satellite upon other amateur signals general conclusion arent Perhaps test results some bearing recent FCC order permits unlicensed operation 100 milliwatt-or-less telemetering units 49-MHz band should expand use Thermal Sensors among non-Ham society sailplaners have never used airborne thermal sensor may understand what does Figs 3 4 give picture miniature radio broadcasting some selectable fre quency between 144 148 MHz mounted sailplane within sealed air container container has calibrated leak means thermistor can detect whether air flowing out container Air flows out con tainer sailplane enters warm moist less dense air typical rising thermal causes thermistor modify transmitter output such way receiver ground emits rising tone rising tone ng air opposite also true Monitoring re ceiver allows glider pilot select best pieces sky purposes Thermal Sensor system product Soaring Products PO Box 117 Ken sington MD 20795 Another solution noise problemuse Cox 049 P-38 Karl Birkels profile scale model weighs 22 oz three channels can Outrun some 60s Photo F Reichers AIRBORNE UNIT 1 OR IF ICE AIR CONTAINER 1-5/16 DIA x 5 WT z HORIZONTAL 1AWAVE DIPOLE 9vTRANSISTOR BATTERY GROUND BASED MONITOR PSB RECEIVER EARPHONE FIGURE 3 PRINCIPLE OF RATE-OF-CLIMB THERMAL SENSOR folks wondering bal ance B-l Model Aviation June 76 p 31 et seq refer sheet 2 page 34 As shown wing outer panel plane should balance within t leading edge outer panel meets leading edge inner panel break leading edge air plane has gentle handling characteristics spite its weird appearance have witnesses fact got out inverted flat spin entered messed-up stall turn Just pull full up hold breath wait dive out thank folks write nice things about column solicit opinions about what should appear intention make things simple possible Please address letters George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 include selfaddressed stamped envelope personal answers RADIO-CONTROLLED GLIDER WITH THERMAL SENSOR DOWN-LINK FROM THERMAL SENSOR ON 144-148MHz EARPHONE UP-LINK TO GLIDER CONTROLS ON 27 53 OR 72 MHz GROUND MONITOR FOR THERMAL SENSOR AUgUst1976 11 . THERMISTOR FLOW METER 2-METER OSCIAMP FIGURE 4 IGURATION OF RC GLIDER AND THERMAL SENSOR
Edition: Model Aviation - 1976/08
Page Numbers: 10, 11
Sound-Level Meters Since have soliciting suggestions column subjects have received several requesting simple circuit sound-level meter Most often thing prompts request concern engine noise following extract letters typical ke clubs today South Jersey Flyaways involved noise problems use infre quently available Db meter have able assemble some information various engine/muffler combinations point have reached con crete position what allowable club flying site assume muffler committee will come out near future recommendation allowable noise levels rub availability Db meter. Would have knowledge available circuit diagram could use construct noise-measuring device own9 Charles Kline 7 Meadowlark Rd Stratford NY its essentials sound-level meter consists four single elements Fig 1 microphone amplifier need expensive signal conditioning can done resistors capacitors display usually meter 1milliamp DC meter will suffice because Db scale can drawn over 0- 1-ma scale using table Fig 2 fact practically VTVM VOM has Db scale will 10-minute recess class checks meters order measure sound levels need assemble necessary components calibrate difficulty starts calibrator usually costs sound-level meter Allied Electronics 1976 Engineering Manual & Purchasing Guide No 760 401 East 8th St Fort Worth TX 76102 still lists low-cost Realistic sound level meter Stock No 910-4028 Type 331028 $4995 formerly carried Radio Shack stores recom mendation interested clubs ob tain will certainly spend money assembling calibrating thing build circuit dia gram want cheaper ap proach have alternative tape recorders have VU meter Volume Units Db indicate recording level have such recorder portable can use Comparative soundlevel meter necessary place recorder some convenient distance engine being tested say 10 ft away put recorder Record mode microphone built-in will have plug appropriate socket Now adjust Vol ume control until meter indicates 0 VU referee engine running referee engine com mittee has decided acceptable Next install other engine same loca tion run VU meter will indicate whether louder VU quieter Geoige Myers MICROPHONEAMPLIFIERSIGNALDISPLAY CONDITIONER FIGURE 1 TIONAL DIAGRAM OF SOUND-LEVEL METER V Db og 20 Log V0 VorA007 22 40 50 56 64 7180 90 100 Db 20 10 5 3 2 1012 3 1 Db lest audible change loudness 6 Db e loud FIGURE 2 SFER FROM LINEAR VOLTAGE OR CURRENT SCALE TO DECIBELS VU referee engine thats really wanted know wont need run magnetic recording tape through machine making measurements unless want record what done As Test Engineer some 20 years experience have decided will always record available data test because data costs less duplicating test setup dont have reduce data until need After measurements completed will discover dont mean much Noise subjective phenomenon barking dog comforting sound its dog youve recently heard burglar-type noises night neighbor its something quite annoy ing Just yesterday talking flying buddy accosted neighbor complained about noise made flying sailplane seems too much running about shouting back forth point am sure still some folks unsatisfied just want build sound-level meter OK Read Tab Books Blue Ridge Summit PA 17214 has just published book Robert P Haviland entitled Build Book Miniature Test Measure ment Instruments $495 Chapter 12 tells build calibrate own sound-level meter package about size Heath Thumb-Tac First Edition First Printing January 1976 local electronics supply house bookstore should have now Its new up-to-date well-written should have no trouble producing useable instru ments instructions given Cali bration another matter think section calibrating sound-level meter will rewritten next edition may permitted moment soap-box Id like say noise prob lems will yield quickly applica tions common sense courtesy other treatment Mufflers avail able convert distasteful snarl crackle engines something like loud hum absolutely no reason us tolerate person refuses use Talk him reason him discipline him within club possible else fails accidently step model Just keep him ground sound broadcast engine travels much further comes flying airplane does ground Limit flying sensible hours determined type neighborhood Avoid flying over homes roads groups people because noise complaints start fear airplane over head will come crashing down arent much position assure anyone cant happen wont need sound-level meters End oratory Recently given copy report submitted AMA Frequency Com mittee FCC entitled results Field Tests Airborne Thermal Sensors Two-Meter Amateur Radio Band dated March 15 1976 have no intention reprinting think credit AMA such well-planned executed documented series tests have conducted 10 Model Aviation name AMA may recognize some participants names have abstracted acknowledge ments W Tynan W3KMV J Colson W3TMZ W Good W3NPS J Strong WN3YJA J Hamblen W3TZ D Clark W3YSC D Goughnour W3RVX D Frey K3AAX R Robin son WA3YEE R Givens T Holder R McNeil Apparently FCC requested report after exhibiting some concern effect RF transmissions Thermal Sensors carried RC sailplanes Briefly tests examined effects Thermal Sensor emissions upon signals 2-meter repeater stations both put output upon signals Oscar 7 satellite upon other amateur signals general conclusion arent Perhaps test results some bearing recent FCC order permits unlicensed operation 100 milliwatt-or-less telemetering units 49-MHz band should expand use Thermal Sensors among non-Ham society sailplaners have never used airborne thermal sensor may understand what does Figs 3 4 give picture miniature radio broadcasting some selectable fre quency between 144 148 MHz mounted sailplane within sealed air container container has calibrated leak means thermistor can detect whether air flowing out container Air flows out con tainer sailplane enters warm moist less dense air typical rising thermal causes thermistor modify transmitter output such way receiver ground emits rising tone rising tone ng air opposite also true Monitoring re ceiver allows glider pilot select best pieces sky purposes Thermal Sensor system product Soaring Products PO Box 117 Ken sington MD 20795 Another solution noise problemuse Cox 049 P-38 Karl Birkels profile scale model weighs 22 oz three channels can Outrun some 60s Photo F Reichers AIRBORNE UNIT 1 OR IF ICE AIR CONTAINER 1-5/16 DIA x 5 WT z HORIZONTAL 1AWAVE DIPOLE 9vTRANSISTOR BATTERY GROUND BASED MONITOR PSB RECEIVER EARPHONE FIGURE 3 PRINCIPLE OF RATE-OF-CLIMB THERMAL SENSOR folks wondering bal ance B-l Model Aviation June 76 p 31 et seq refer sheet 2 page 34 As shown wing outer panel plane should balance within t leading edge outer panel meets leading edge inner panel break leading edge air plane has gentle handling characteristics spite its weird appearance have witnesses fact got out inverted flat spin entered messed-up stall turn Just pull full up hold breath wait dive out thank folks write nice things about column solicit opinions about what should appear intention make things simple possible Please address letters George M Myers 70 Froehlich Farm Rd Hicksville NY 11801 include selfaddressed stamped envelope personal answers RADIO-CONTROLLED GLIDER WITH THERMAL SENSOR DOWN-LINK FROM THERMAL SENSOR ON 144-148MHz EARPHONE UP-LINK TO GLIDER CONTROLS ON 27 53 OR 72 MHz GROUND MONITOR FOR THERMAL SENSOR AUgUst1976 11 . THERMISTOR FLOW METER 2-METER OSCIAMP FIGURE 4 IGURATION OF RC GLIDER AND THERMAL SENSOR