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HelicopterMain Discussion › opto isolators
11-28-2005 05:43 PM  12 years agoPost 1
rkeith2

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Norco, CA

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Guys -

Anyone know where to get schematics on how to construct these for the servos to help prevent rfi back into the receiver?


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11-28-2005 09:49 PM  12 years agoPost 2
Wisdom-Seeker

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Danville, CA

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The only way that an optical isolator would help you is if you ran the servos off of a separate battery from the receiver. The RFI generated by a servo is from the rapidly changing current demand on the battery which can be coupled back into the receiver through the power line. If the receiver is designed correctly, it should already have power filtering in place to prevent this kind of problem.

The other way to prevent this is to keep the antenna far from any power wires in the heli.

--

Wisdom-Seeker
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11-28-2005 10:36 PM  12 years agoPost 3
Ace Dude

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USA

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Here are the ready made ones:

http://forgues-research.com/

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11-28-2005 10:50 PM  12 years agoPost 4
PaulJC

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Hertfordshire UK

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As wisdom seeker said, you would need 2 seperate batterys to make it effective, have you tried ferrite rings aon the servo lines, the futaba website has a good section on combating RFI

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11-30-2005 05:06 PM  12 years agoPost 5
rkeith2

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Norco, CA

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opto

Yes I plan to do dual batteries and isolate servos from rx


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11-30-2005 05:25 PM  12 years agoPost 6
Ron Cosby

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Shreveport, Louisiana

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You might want to consider an I4C isolator, it is compact and allows for the 2nd battery. I have one on my Gasser and have had no problems at all with it. It's not an optic isolator however, but it works. I went with it after I saw so many of the large scale plank fliers use them. There is a dual battery Gem switch available now that made the setup real easy.

http://www.i4cproducts.com/

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11-30-2005 05:51 PM  12 years agoPost 7
PaulJC

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Hertfordshire UK

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The I4C looks good but it contradicts itself:
The signal goes out of the receiver but no electronic noise returns because the servo power is isolated.
(both batteries share a common ground).
If you put a scope on the signal line of a servo it will show nothing until you ground it to the receiver ground.

Granted this will stop any noise on the positive side of the power supply from affecting the servo's but it's unlikely to find much noise there anyway. The main place you will find noise is on the signal and negative lines, the signal line is still connected to the receiver as is the negative.

I'm not knocking the product as anything which allows the use of two batterys and allows the servos more current drawing capabilitys is good but i would be suprised if it isolated much.

Optoisolation is the only true isolation method as none of the servo lines are connected to the receiver at all.

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11-30-2005 06:10 PM  12 years agoPost 8
rkeith2

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Norco, CA

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The i4c stuff looks nice but opto is truly segregated with dual batts as well. I am trying the EDR 111


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11-30-2005 07:06 PM  12 years agoPost 9
wolfdad

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Southern Maryland

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You might also want to take a look at the JoMar isolator available through Al Wirt out at Starwood Scale.

wolfdad sends....

"There are those who have...and, those who will" IRCHA #2117, AMA #70068, Turbine Waiver #105

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HelicopterMain Discussion › opto isolators
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