Nick Brotherton Posted January 23, 2011 Share Posted January 23, 2011 Hi all, Am just setting up a plane with Spektrum DX7 and AR6200 rec'r.I am using a 6v NIMH battery as I have done before (conscious that Spektrum requires a higher voltage to avoid brown outs etc).>>BUT this time I am getting servo chatter on the elevator servos ( 2 x JR591’s connected to elev channel with a Y lead).>>It doesn’t happen every time I move the elevator stick but on occasions and it seems to happen more just as the servo is moving back to neutral.>>I have used this setup on many other planes without any problem. BUT if I fit a regulator and take the voltage down to 5v it seems to be OK so maybe I should be doing this with all my models. However>>I am puzzled as this is the first time its happened. (or maybe the first time I have noticed it). All the servos are new JR R591's but it only happens on the elev channel.Has anyone else experienced this and are all you spectrum users out there running with a 6v or a 4.8v receiver battery?>>Any help appreciated. >> >> >> Quote Link to comment Share on other sites More sharing options...
Peewhit Posted January 23, 2011 Share Posted January 23, 2011 Hi Nick, I use Spektrum gear - DX7 and more recently DSX9 with mainly 6200 receivers. On my Typhoon, like you, I opted for a 6v set up. What I did not appreciate is that a newly charged 6v NIMH battery can output up to 7.2V, and I blew two expensive servos. Fitting your regulator solves your problem and this indicates that it may well be an over voltage issue. The low voltage brown out issue associated with Spektrum receivers is very much a myth as they will operate perfectly down to about 3.3V. All my models are now on four cell 4.8v and I have never had a brown out. I cannot see any difference in servo response using 4.8V as opposed to 6V, and a further advantage of 4.8V is that the current drain is less, giving longer flight times, and the proportional voltage drop is less. In summary, I have been down the five cell 6V route, gone back to four cell 4.8v, and would not now run anything on 6V without that crucial regulator. Hope this helps Quote Link to comment Share on other sites More sharing options...
Nick Brotherton Posted January 23, 2011 Author Share Posted January 23, 2011 Hi Peewhit, Thx for the reply. I have had this discussion before and find it really infuriating when the USA web site for JR state torque values for all their servos at 4.8 AND 6 volts. But in the UK they say that they can only run on 4.8v. I'm sure they are all made in the same factory in the Far East so why the difference? JR and Spektrum were (until recently) working together but it seems that you cant use their products in the same installation. (if worrying about brownouts which maybe, as you say, is a myth) . In the past I have risked using 6v on several other models with no issues of blown servos. I am now wishing I was using Futaba instead but its a bit costly to move across completely. I just looked at the latest servos on the Macgregor website and they are still stating 4.8 volts only! Still not happy. Nick Quote Link to comment Share on other sites More sharing options...
Peewhit Posted January 23, 2011 Share Posted January 23, 2011 Hi Nick, I am confident that your JR servos will run on 6V, as will most other servos. My key point is that a fully charged five cell NIMH will deliver more than 6v and up to 7.2V. This is where the servos will not be happy and where that voltage regulator comes into its own. I used to use Futabe kit and changed to Spektrum quite quickly afterwards. Much prefer the Spektrum stuff. Quote Link to comment Share on other sites More sharing options...
John Lee Posted January 23, 2011 Share Posted January 23, 2011 As you say the MacGregor website is specific on this & states:'The NES591 can only be used at 4.8v.'There was correspondence in the RCM&E a few years ago when an old friend Dave Cotton reported the loss of a model using 591's on 6volt & Dave Wiltshire confirmed that they were vunerable on higher voltages. Edited By John Lee on 23/01/2011 18:46:04 Quote Link to comment Share on other sites More sharing options...
flytilbroke Posted January 23, 2011 Share Posted January 23, 2011 I have had brown outs using Spektrum. I have witnessesd other flyers have brown outs. It can be a problem, one which has often been reported. I realised today that I still have a four cell pack in my Panic, and it has barn doors for control surfaces and a 7100 Rx. So, some you win. John Lee has the right of it, some servos should not be used at a higher voltage than that given from a 4cell NMh pack. Quote Link to comment Share on other sites More sharing options...
Nick Brotherton Posted January 23, 2011 Author Share Posted January 23, 2011 I may have found a solution. I tried 4.8 v but it did chatter on this voltage too. I then swapped the Y lead, no change either. So I tried substituting one of the 591's with a 577 and hey presto, no chatter! Odd or what? It only chatters when 2 x 591's are connected with a Y lead. with 2 x 577's no chatter, 1 x 577 and 1 x 591 no chatter. Some odd thing with the 591 servo spec I guess, but I am at a loss as to what it could be. Cheers. Quote Link to comment Share on other sites More sharing options...
Vecchio Austriaco Posted January 23, 2011 Share Posted January 23, 2011 Brown outs: The higher voltage doesn't help - you need to have a sufficient battery capacity so the voltage doesn't break down if all servos are moving with high forces. So my advice is to increase the capacity and not to use more cells! Also be sure that none of your servos run against any mechanical block - if a servo is blocked it will take much more current and the voltage may break down. Set the servo travel correct - and look also at servos which are behind a mixing functions. Mixing can increase the servo travel. Quote Link to comment Share on other sites More sharing options...
Alan Cantwell Posted January 23, 2011 Share Posted January 23, 2011 i was just going to post excatly the last posters thoughts regarding capacity, i only run 4cell packs, and one of them is in a dirty great corsair, with a zenoah 62, but, its a 4500 sub C size pack Quote Link to comment Share on other sites More sharing options...
Nick Brotherton Posted January 24, 2011 Author Share Posted January 24, 2011 More developments, this morning when I resumed work on this model with the 2 different servo types, it started jittering again! Finally solved it with a 4.8 v battery which was slightly low ie 4.6v, there was no jitter so i retired the regulator with the voltage set at just 4.8 and it was fine, must've had the voltage set too high or, more likely, my multimeter isnt accurate. Incidentally it only causes jitter with servos connected using a y lead and not single servos. Thx for all the replies. Quote Link to comment Share on other sites More sharing options...
flytilbroke Posted January 24, 2011 Share Posted January 24, 2011 I hope that is the problem solved Nick. Quote Link to comment Share on other sites More sharing options...
Lee Smalley Posted January 24, 2011 Share Posted January 24, 2011 some servos jitter if you get too close with the tx Quote Link to comment Share on other sites More sharing options...
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