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HomeRC & PowerAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › Regulator question
02-06-2008 03:24 PM  10 years agoPost 1
kcass518

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Port Washington, NY - USA

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Evo 50, all digital servos, AR7000, GY401, TJPro.

I'm thinking of going to 6v NiCds, putting a regulator between the receiver and the gyro. My question is, the gyro has two plugs into the receiver. Do I only put the regulator between the rudder channel and the gyro? Or do I need to do something for channel 5, too? Any suggestions on which regulator to use for this purpose?

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02-06-2008 03:32 PM  10 years agoPost 2
BarracudaHockey

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Jacksonville FL

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Depends on what you want to do.

You don't need a regulator with a 5 cell pack but if you go that route you need a tail servo step down between the gyro and tail servo, about 4 bucks for the Align one.

If you want a full regulated system then the voltage you choose will determine if you need a tail step down. Radio South has regulators in 5.1 and 5.3v configurations that don't require a tail step down, anything more than 5.6 or so you will want a tail step down or a regulator with a separate tail output but honestly that really doesn't sound like you need something that complicated, just run a 5 cell pack and a step down to the tail servo and you'll be fine.

Andy
AMA 77227
http://www.jaxrc.com

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02-06-2008 03:56 PM  10 years agoPost 3
kcass518

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Thank you, BH. I guess that makes me ask, what's the difference between a 'step down' and a 'regulator'. Also, according to Futaba's website, the GY401 needs this:

Voltage- use only with a 4.8V battery. (if you use it with a
higher voltage battery it needs to be regulated to 6V)

Is that true?

I'm not into hard 3D, yet, but I do want to beef up my power supply because of the AR7000 and the digital servos. I am doing loops, rolls, FFF, and quick turns already. Also, I need more weight in the nose, so I figured a five cell sub C would do the trick. I just don't want to burn anything out!

Your help, as always, is appreciated!

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02-06-2008 04:01 PM  10 years agoPost 4
BarracudaHockey

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Jacksonville FL

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A regulator is capable of more current delivery and delivering a set voltage. A step down just reduces the voltage in by .7v

As for the 4.8v warning what it should say is "a fully charged 4 cell pack" which, as you probably know is 5.3 or 5.4 volts anyways, just like servos that are rated for 6v are acutally saying "works with a fully charged 5 cell pack" which is around 7v

Don't make things more complicated than you need to. A 5 cell pack with a tail step down is all you really need.

Andy
AMA 77227
http://www.jaxrc.com

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02-06-2008 04:06 PM  10 years agoPost 5
kcass518

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Sounds good to me. Thank you!

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02-06-2008 04:26 PM  10 years agoPost 6
helimatt

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Lafayette, IN

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Ooops, be careful here!

BarracudaHockey, you are correct right up to the point where you say a step down is all he needs with the 5-cell NiCd or NiMh.

The step down reduces the voltage by .7V or so, correct. A fully charged 5-cell pack will be over 7V, so the tail servo would be seeing well over 6V much of the time. Sounds like it could be too much for many tail servos.

I know because I tried that setup and burned up the motor on my Logictech 6100G tail servo. It is rated to 5.5V.

A regulator would not only step down a fixed amount, but would deliver exactly the rated output voltage, within its tolerance of course.

It might be fine with the Futaba gyro, but probably not with the servo, and probably not a good risk to take.

I think there is a small regulator available for this purpose- Spektrum just started marketing one with two outputs.

By the way, you only need to step down the postitive lead if you go that route, no need to step down the Channel 5 gain input lead.

Never, ever, ever, ever give up.

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02-06-2008 05:07 PM  10 years agoPost 7
BarracudaHockey

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Jacksonville FL

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You have a good point...

I'm not sure about the Spectrum regulators but http://www.radiosouthrc.com sells something they call a switch safe regulator, at 5.3v everything should be happy.

Andy
AMA 77227
http://www.jaxrc.com

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02-06-2008 05:21 PM  10 years agoPost 8
kcass518

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Port Washington, NY - USA

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Ah, but if I do that, I don't get the benefit of 6 volts in the cyclic and collective servos.

I just ordered the unit from Horizon - it says it is a 5.8v to 5.1 v step down voltage regulator. I would think that putting it between the receiver and the gyro would work, no?

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02-06-2008 05:35 PM  10 years agoPost 9
racingstripe

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Sacramento, CA

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five cell sub C
That behemoth will weigh 11oz.

Are you that tail heavy?

A 5 cell 1950NiMH is about 7.5oz.
http://hangtimes.com/giantrxpacks.html

Not sure how much this one weighs...
http://www.horizonhobby.com/Product...ProdID=JRPB4350

You can remove the horizontal fin unless you need it to see the tail.

andy-

Proofread carefully to see if you any words out.

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02-06-2008 05:49 PM  10 years agoPost 10
kcass518

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Hmmm. More good points. Re the JR pack, is 1400 mah enough? I guess I should see how much weight I need to add to the nose to get in balance before ordering a new battery pack!

Also, Helimatt, according to the info on the Spektrum dual input/output regulator, they suggest using the two outputs for the rudder and the gain channels. I don't know if they're just suggesting it, or if it is necessary. It would make a difference to me because my throttle servo is also 4.8v only, so I thought I would use the extra output for that if I went in that direction.

And, BH, does the step-down regulator only reduce the applied power by 0.8v, or does it bring it down to 5.1v regardless of the power supplied?

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02-06-2008 06:02 PM  10 years agoPost 11
Andy from Sandy

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Bedfordshire, UK

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The Align step down tells you it is a 5.1volt step down because their regulator has an output voltage of 5.8volts. It is simply a diode. What ever voltage you feed it the output will 0.7 volts lower.

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02-06-2008 06:25 PM  10 years agoPost 12
racingstripe

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Sacramento, CA

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the JR pack, is 1400 mah enough?
Probably not. That was the highest capacity pack I saw that wasn't NiMH or a sub-C.

I would not use any NiMH battery smaller than a sub-C with digital servos. The only exception is a pack that uses Sanyo HR 4/5FAUP 1950 cells, designed for "high-rate discharge".

andy-

Proofread carefully to see if you any words out.

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02-06-2008 06:33 PM  10 years agoPost 13
Funky Trex

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Westerville, OH - USA

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I use MPIs to regulate my tail servos. The output voltage is always 5.4 no matter what voltage you are running to the RX. I verified mine with a volt meter. My results when checking the actual voltage at the tail servo using the Align step down with NiMh 5 cell packs was very discouraging

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02-06-2008 06:44 PM  10 years agoPost 14
Zaneman007

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Texas - USA

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I'm thinking of going to 6v NiCds
I would not attempt to regulate a 6v Nicad to 6v or 5.8v for that matter. If you use a regulator go with a 7v Lipo or Lion battery.
The regulator will give you a constant output say 6v then the step down will take it to 5.3 for the servo.

If you are simply going to use the 6v Nicads, unregulated, then your voltage to the tail servo via the step down will change as the voltage in the Nicad decreases. The voltage to the tail servo will always be .7 volts less than the voltage of the Nicads.

P.S. the second plug on the gyro is for the gain adjustment via the radio. If it only has one wire to it, as seen on the GY401 placing the stepdown between the Rx and the gyro will work. But, if it has all three wires on both conectors as seen on the GY611, you will have to remove the red wire from the gain lead, or you will end up bypassing the stepdown.

Old Guys Rule!

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02-06-2008 06:49 PM  10 years agoPost 15
Andy from Sandy

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Bedfordshire, UK

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What does the acronym MPI stand for?

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02-06-2008 06:59 PM  10 years agoPost 16
Funky Trex

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Westerville, OH - USA

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The voltage to the tail servo will always be .7 volts less than the voltage of the Nicads
Zaneman, have you checked to see if it always steps it down .7 despite the input voltage? We used a volt meter to check 2 different setups at our field that were using the align step downs and we found that the higher the voltage input, the less they were reducing the voltage to the tail servo.

AndyfromSandy, MPI makes the regulator I was referring to. The one I use for my tail servos is the second regulator listed on this page. http://www.troybuiltmodels.com/Regulators3.htm

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02-06-2008 07:08 PM  10 years agoPost 17
kcass518

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Port Washington, NY - USA

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Zaneman - thank you for reminding me! Yup, it's one wire and has nothing to do with the power supply. I think the VR 5203 should do it for me.

But, I'll let you all fight it out. I'm having fun reading the posts.

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02-06-2008 07:13 PM  10 years agoPost 18
Zaneman007

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Texas - USA

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I have a home made step-down "diode" on my Tx. I am running the Tx on an 11.1v lipo. I have checked the voltage several times, at different voltage levels, and the variance in the voltage before and after the diode is constant.

Unless there is some min voltage that would cause this to change? But I have never tested this below 10 volts. All of the literature that I have read, indicates that voltage drop is consistent. If I'm missing something here, please key me in.

I'm doing more "homemade" stuff as I get more experience. I just can not see paying $16 bucks for a $1 buck diode?

Old Guys Rule!

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02-06-2008 07:24 PM  10 years agoPost 19
Funky Trex

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Westerville, OH - USA

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Not missing anything, I am just curious if anyone else had the same results. Everything I have read says the same thing you stated. Both of us at the field were using the same model of Align step downs so I haven't checked any of the step downs or diodes from other sources. Maybe we both had bum step downs

When we checked mine at the field, I was running a 5 cell 3600 Nimh pack. My voltage was 6.8 volts at the RX and the tail step down was only dropping it to 6.6 volts. We plugged in my battery on his heli (with a different align step down) and had the same results. When we checked them on his regulated 6 volt system (we verified this with the meter before checking the voltage after the step down), his regultator dropped votlage to 5.4 and mine only dropped it to 5.5.

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02-06-2008 08:47 PM  10 years agoPost 20
BarracudaHockey

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Jacksonville FL

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My question would be...How are you checking them? I've verified mine with an inline meter, not simply reading whats on the pins w/o a servo plugged in, and the work just fine. Since I have a 611 on my Raptor it's easy to compare the voltage the gyro is getting with the voltage on the tail servo that way.

Andy
AMA 77227
http://www.jaxrc.com

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HomeRC & PowerAircraftHelicopterRadio - Servo - Gyro - Gov - Batt › Regulator question
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