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Use of JR servoes on Futaba, possible ?

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Old 05-18-2003, 04:49 PM
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affas
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Default Use of JR servoes on Futaba, possible ?

Can I use all kind of JR servoes on my Futaba system ? Both digital and analog`s? Any restriction ?

Best regards
Alf Hansen
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Old 05-19-2003, 01:41 AM
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DMcQuinn
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Default Use of JR servoes on Futaba, possible ?

You can use any JR servo with the Futaba receiver. No problem. No restriction.
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Old 05-19-2003, 01:45 AM
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John H.
 
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Default Use of JR servoes on Futaba, possible ?

No problem works great. But do not use with 6 volts.
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Old 05-19-2003, 01:58 AM
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Default Use of JR servoes on Futaba, possible ?

Yes, you can use JR servos with Futaba receivers using either 4.8v or 6v setups without any issues. I've been doing it for years, and its quite common on the larger aerobatic models to mix and match servos in 4.8v or 6v systems with either Futaba or JR receivers. With Airtronics servos, you will have to redo the connector as the pin out is different.
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Old 05-19-2003, 01:59 AM
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Default Use of JR servoes on Futaba, possible ?

futaba signal is 3.3 volts JRs is battery voltage JR servos
do not like the large difference
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Old 05-19-2003, 05:50 AM
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WreckRman2
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Default Use of JR servoes on Futaba, possible ?

I run a Futaba RX with JR servos at 6v with no problems and no regulator.
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Old 05-19-2003, 08:47 AM
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Dansy
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Default Use of JR servoes on Futaba, possible ?

I only run JR servo's and I only run 6.0 volt regulator, so yes the JR servo's are happy on 6 volts.

I run the following, 7005, 8231, 8411, 8411 sa, 331, 3421, 8401, 3401, 368, 703, 341, and the one I forgot....
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Old 05-19-2003, 11:01 AM
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Default Use of JR servoes on Futaba, possible ?

Originally posted by John H.
futaba signal is 3.3 volts JRs is battery voltage JR servos
do not like the large difference
But both Futaba and JR themselves say its ok to run the servos and receivers on 6 volts. And field use shows so many people running the large aerobatic airplanes with JR8411's at 6 volts with both JR and Futaba receivers without any issues at all. If the manufacturers say its ok, it probably is.
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Old 05-19-2003, 04:19 PM
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Default Use of JR servoes on Futaba, possible ?

Yes, no prob at 4.8 or 6v.

My most common setup is:

Transmitter Futaba 9c
Receiver Hitec 555
Switch JR deluxe
Servos Mix of JR Hitec and futaba. Some Digital, some Analog. Most often mixed in the same plane.

I haven't found a problem yet, except if your battery has a futaba plug, you have to trim it to fit into the JR Switch.

Just do a good check of everthing, and a range check at full throttle before flying.
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Old 05-21-2003, 01:33 AM
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Default Use of JR servoes on Futaba, possible ?

Originally posted by sfaust
But both Futaba and JR themselves say its ok to run the servos and receivers on 6 volts. And field use shows so many people running the large aerobatic airplanes with JR8411's at 6 volts with both JR and Futaba receivers without any issues at all. If the manufacturers say its ok, it probably is.
Ask Futaba if it is OK to run JR servos with Futaba rx at high voltage :-)

I think what John is referring to, is that the Futaba RX regulates the signal (the white or orange wire) to about 3.3 volts. So a logic "high" signal at the servo is 3.3 V minus any voltage drop over the connectors and harness.

Now a JR servo's input comparator (the thing that decides if the signal is high or low) is referenced to the supply rail of the servo. So if the supply rail is low, like 4.8 V, then a 3.3 v reference is marginal but OK. If you have a very high supply voltage (like a 5 cell nicad off a charge) then you are going to have a very high rail, like a 7 volts and then the 3.3 V signal no longer appears as a valid "high".

You might get away with it with losses in long leads, etc. I don't run them that way. Before I went to regulators I had servos that would not move until the peak came off the batteries. Kind of scary
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Old 05-21-2003, 01:56 AM
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Default Use of JR servoes on Futaba, possible ?

I've never run into the problem you had with servos that wouldn't move. I mostly used JR 8411, 4721, and 2721 without any issues at all on 6v with Futaba receivers. I asked Futaba and JR both about running either manufacturers servos with their receivers at 6v, and they both stated that it was fine. I was told that on occasion with a 6v system right off fast charge, that I would get the jitters on the JR servos. He stated this was due to the high voltage when the fast charge was terminated, but the voltage would dissipate normally after sitting for a few minutes after you take it direct off the fast charge. Thats always worked for me, and I haven't seen any problems when doing so.

I also only saw the jittering when turning on immediately after a fast charge. I never saw the symptoms when turning on direct off an C/10 overnight charge, which is what I normally use. This seems to correlate with what you are saying. When taken off a fast charge, artifical battery voltage is high enough to cause the 'high' to be invalid. However, when the battery sits a few minutes for the artifical high voltage to dissipate, the 'high' signal then comes back into a valid range, and the servo operates properly.

I also wonder if using PCM vs PPM would have any impact on this situation.
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Old 11-20-2003, 05:14 PM
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mike greene
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Default RE: Use of JR <span class=

I used futaba recever with 4721 servoes and all the servoes hum like they are tring to find center the guy i bought the plane form says they have always humed . is this OK[X[:-](]
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Old 11-21-2003, 10:04 AM
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Default RE: Use of JR <span class=

This has bugged me for a while.
JR in the UK (macgregor ind) do not reccomend 6volts for any of their gear. And tell you not to use it.

Surely its the same stuff as you use over the water (minus the obvious Mhz difference)
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Old 11-21-2003, 12:07 PM
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Default RE: Use of JR <span class=

ORIGINAL: rob g
This has bugged me for a while.
JR in the UK (macgregor ind) do not reccomend 6volts for any of their gear. And tell you not to use it.
I never realized that they had different messages on this based on what side of the pond you live on. In the US, not only do they say its fine, but they also quote the specs using both 4.8v and 6v.

Maybe the US is their testing grounds so they can decide if they should tell the rest of the world that using 6v is ok Wouldn't that be scary!
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