McG 6969 Posted March 6, 2020 Share Posted March 6, 2020 Hello to all, I have a QUESTION please, gents: My plan is to use a Corona DS 238MG for the elevator. Before installing, I would like to test run it for a while on a servo tester. With the tester I have (brand HJ, see above), the Servo Refresh Rate can be set to 50 Hz (20 us), 125 HZ, (8 us) or 250 Hz (4 us). So, this is what I found about the different modes: 1/ > Manual Mode 50Hz Analog servo signal cycle 20µs 2/ > Bit Mode (Neutral) 125Hz Digital servo signal cycle 8µs 3/ > Automatic Mode 250Hz Digital servo signal cycle 4µs The 50 Hz rate is used for analog servos, but this one being digital, should I use the 125 Hz or 250 Hz selection… ??? I have downloaded several data sheets for the Corona, but none indicates the appropriate rate. Can a helpful soul bring some light in the tunnel, please. Thanks in advance Cheers Chris Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted March 6, 2020 Share Posted March 6, 2020 Chris, this from tinted net Conventional Servo Motor Timing A signal of 20 ms has a frequency of 50 Hz. The width of the pulse is varied between 1 and 2 ms to control the motor shaft position. A pulse width of 1.5ms will cause the servo shaft to rest in the 90 degree position, the center of its travel Quote Link to comment Share on other sites More sharing options...
Attilio Rausse Posted March 6, 2020 Share Posted March 6, 2020 run it at 50 hz and it will be fine, the problem arises when you run an analog at a High refresh rate will cause it to overheat. I assume that you just want to make sure it works OK. if you have mixed analog and digital in a model you would run them at the lower rate. Higher rate is for finer control and greater holding power (Heli tail rotor) but the servo you mention is fairly standard. Quote Link to comment Share on other sites More sharing options...
Nigel R Posted March 6, 2020 Share Posted March 6, 2020 Chris, the Corona is digital and will likely be happy with any of those rates. Stick with the 50hz rate for analogue. "Higher rate is for finer control and greater holding power " Have to disagree there, the control signal refresh rate makes no odds to either of those two properties. The internals of a given digital servo will adapt to a range of refresh rates. Analogue servos will expect 50Hz and unlikely to work very well at anything else. Higher rate is good advertising material. Edited By Nigel R on 06/03/2020 10:51:09 Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted March 6, 2020 Share Posted March 6, 2020 Higher refresh rates WILL give a faster response but it's doubtful whether us mere mortals could tell the difference. I'd imagine you would get better performance on gyro controlled applications such as tail rotors though. Some Sbus systems default to 9us (can't find mu on my keyboard ) but I've no idea what uses 4us! Quote Link to comment Share on other sites More sharing options...
McG 6969 Posted March 6, 2020 Author Share Posted March 6, 2020 Thank you for your extremely fast help, gents. It is indeed just to check if my servos are working properly before installation. As I have a mix of 9018MG (analog) on the ailerons and the Corona (digital) for the elevator, I'll stick to the 50 Hz refresh rate. Thanks again. Cheers Chris Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted March 6, 2020 Share Posted March 6, 2020 Posted by Bob Cotsford on 06/03/2020 11:33:33: Higher refresh rates WILL give a faster response but it's doubtful whether us mere mortals could tell the difference. I'd imagine you would get better performance on gyro controlled applications such as tail rotors though. Some Sbus systems default to 9us (can't find mu on my keyboard ) but I've no idea what uses 4us! Shouldn't 20µs, 8µs and 4µs actually read 20ms, 8ms and 4ms anyway? i.e.50Hz = 20ms. Quote Link to comment Share on other sites More sharing options...
Martin McIntosh Posted March 6, 2020 Share Posted March 6, 2020 Don`t run the servo for more than 1min on the tester. I have heard that people are complaining that they burn out after an hour or so! Pretty standard cheapo servo which will do the job. Have one or two myself. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted March 6, 2020 Share Posted March 6, 2020 Bet they have no sense of smell, as well as sense. Poor servo getting hotter and hotter, slamming from end to end. Bet they pulled the legs off spiders when young. Quote Link to comment Share on other sites More sharing options...
Gary Manuel Posted March 6, 2020 Share Posted March 6, 2020 I've seen a video of a servo tester (I'll see if I can find it), that runs from 800µs to 2200µs. A lot of servos don't cover that range so they will be being driven PAST their maximum limits by the servo tester - slamming into the end stops on each movement. HiTec for example only cover from 900µs to 2100µs. A typical transmitter covers from 1000µs to 2000µs (on unextended limits). No wonder the servos burn out on testers. Edit - HERE's a link to the video I was referring to. It's actually the exact same one the original poster is talking about. Edited By Gary Manuel on 06/03/2020 17:07:38 Quote Link to comment Share on other sites More sharing options...
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