john melia 1 Posted November 2, 2014 Share Posted November 2, 2014 All my servos on my sbach are digital apart from the elevator servos which are hitec 654mg's ultra torque , can anyone explain what would happen if I changed the frame rate from 22ms to 11ms , I know the servos would be quicker , but what would happen to the elevator servos with this frame rate Quote Link to comment Share on other sites More sharing options...
Hangar 9 nut Posted November 2, 2014 Share Posted November 2, 2014 I don't know what happens but you should not use analogue servos at 11ms I think it might burn them out or they would glitch all the time Quote Link to comment Share on other sites More sharing options...
john melia 1 Posted November 2, 2014 Author Share Posted November 2, 2014 Yeah thats why I need some info , I tried them at 11ms today , and they seemed fine , but I dont know enough about it Quote Link to comment Share on other sites More sharing options...
Phil Green Posted November 2, 2014 Share Posted November 2, 2014 Hi John. some conventional servos will be ok at a higher framerate, I checked the 645 datasheet and it doesn't mention maximum refresh rate. I can see four options - 1) Swap the Hitecs out 2) connect an ammeter in series with your battery. Leave the wing servos off. Monitor the current at 11ms and at 22ms through all elevator servo positions, with & without a load. If at 11ms you notice they are drawing more current, then they will burn. The problem is with the H bridge at the output of the servo amplifier - if as is likely the internal pulse stretchers happen to run over 11ms, they could overlap, enabling both high and low sides of the H bridge and effectively short the battery. 3) go to 11ms but fit a pwm framerate divider inline with the Hitecs. 4) leave everything as it is. Will you notice 11 milliseconds? You know that with some systems the framerate isn't the information rate, ie at 11ms they just send the same width pulse twice as often? Cheers Phil PS I do wish people wouldn't call conventional servos 'analogue'. I use analogue servos with my Staveley Analogue propo system. They don't have pulses at all, a proportionally varying voltage controls the servo position. Edited By Phil Green on 02/11/2014 18:24:44 Quote Link to comment Share on other sites More sharing options...
ben goodfellow 1 Posted November 2, 2014 Share Posted November 2, 2014 good question john , i run digi servos and the frame rate setting hadnt really occured t me .. any one know wha you should typicaly epect to gain when setting at higher frame rates ????? fly low Quote Link to comment Share on other sites More sharing options...
Former Member Posted November 2, 2014 Share Posted November 2, 2014 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted November 2, 2014 Share Posted November 2, 2014 I don't think us mere mortals would notice any difference at all between 11 and 22mS. At 22mS, the servos are already being updated about 45 times a second. Quote Link to comment Share on other sites More sharing options...
john melia 1 Posted November 2, 2014 Author Share Posted November 2, 2014 I noticed quite a difference in servo speed when I switched from 22ms to 11ms , phil whats a pwn frame rate devider Quote Link to comment Share on other sites More sharing options...
Phil Green Posted November 2, 2014 Share Posted November 2, 2014 What do you mean John, transit speed? that shouldn't change at all. Its only the response time that should change. Quote Link to comment Share on other sites More sharing options...
john melia 1 Posted November 2, 2014 Author Share Posted November 2, 2014 While I was at the field my mate was watching me going through some pre flight checks , and he commented on how slow the elevator seemed to be moving (hs 645mg x 2 ) , he asked if they were digital or analogue servos ,I told him analogue , he said if they all had been digital I could swap to 11ms on my tx , I tried the 11ms and the speed of the elevator servos did seem to be quicker , but as I stated earlier i wasnt sure if any damage would be done , so I put it back to 22ms , could have all been in my head , but the others watching said they looked to be moving quicker . Quote Link to comment Share on other sites More sharing options...
Phil Green Posted November 2, 2014 Share Posted November 2, 2014 Presumably if you have 2 elevator servos then its a substantial model. I wouldn't risk it. If you do want to go 11ms then I would strongly suggest you swap out the Hitecs for digitals. Your call though. Cheers Phil PS they're not analogue servos Quote Link to comment Share on other sites More sharing options...
Hangar 9 nut Posted November 2, 2014 Share Posted November 2, 2014 Its response time of transmitter to receiver that is quicker so it would seem the servo is quicker as reaction time is quicker Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted November 2, 2014 Share Posted November 2, 2014 You believe we can detect a 10ms faster response time with the unaided naked eye? BEB Quote Link to comment Share on other sites More sharing options...
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