martno1fan

hi after reading several threads about y harnesses im confused can someone tell me how using one bypasses the rx thus giving a full 6 volts to the servo .suerely you still get 6 volts from the rx if you go through there without the y harness?.if thats not the case how does the y harness bypass the rx surely the power will still go to the rx first then the servo how does it bypass it by using a y harness.

DaveMarles

The Y harness will carry more current to the rudder servo than going via the receiver circuit board. I thought it was BS when I first saw it written about, but after a few tests I found that it can make a significant improvement on boats that need high servo power.

martno1fan

well thats what some have said also but i just dont get it? how does it work can it really bypass the rx ?.

DaveMarles

The power to the servo goes through the red and black wire which will be connected direct from battery to servo with a Y lead and so its bypassing the pc board on the receiver.

martno1fan

ok thanks for that i havent noticed any diff when trying it on my boat and on a sailboat for the sail controll thats why i doubted it actually worked.

John Howell

When the power goes through the RX it will normally only allow 4.8 volts through to the servo. This means your 1/4 scale servo isn't delivering the full torque that it is rated to ie. your 12kgs is really only 8kgs. When you use the Y harness and bypass the RX you will allow the full 6volts to operate the servo at its peak.

martno1fan

i know thats what some say but i doubted it worked as i noticed no change when i tried it .who says rx doesnt allow 6 volts through? is that a fact or just a guess?.if thats the case why do they make 6 volt receiver packs?.

John Howell

It's a well know fact. - that is why Y Harnesses are used. Go and test it yourself. On my JR RS300 RX it only registers 4.05 volts on the streering with a fully charged 6v humpback battery.

martno1fan

you say its a well known fact but ive yet to see any evidence that it actually works,if you attach a battery up to a servo it does nothing as you need the signal from the rx? so how can it bypass the rx when the servo needs the signal from the rx to work?.and i have tried it on a sail servo and a ruder servo ive not noticed any diff,admitted i dont have a volt meter .

John Howell

LOL, how can you say you saw no difference and you didn't even measure it.

Don't take my word for it - go and get yourself a volt meter and test it yourself.

BTW there are three wires used to operate a servo and the RX only needs to send a signal down one of them. If the the servo has power and the RX sends the signal down the one wire it will work the servo.

There your now an expert.

martno1fan

i still say it wont work i have seen no evidence yet!! sureley if its true someone can show me some evidence?.like i said though connecting a battery up to a servo direct does nothing?

MrMikeG

To really see it you need to need MAX servo torque, no offence but at 35 mph you could use a standard servo to steer your boat so your 1/4 scale is so overkill already that you will not see the benefit unless you can see the difference between .16 sec and .13 sec? Some recievers do allow 6 volts, the benefit there is simply thicker wiring allowing more current.

martno1fan

my boat is big so no a normal servo would not work,least not for long!!i dont run 1/4 servos either just high torque metal geared servo for rudder.i still say a y harness will not do what has been said though but what do i know .i know some guys running very big boats on this site with no y harness not naming names but very well known maybe they will chime in and give a view on this.by the way 35 mph was after the 2nd run shes faster now which is not bad for a trimmer motor with no pipe!!.

glennb2006

Hi Martin,

you need to measure the voltage going into your servo between the red and black conductors. Feed from the RX to the servo will bein the range to 4.8volts (ish).

Even with the 6 volt pack.

The Y lead as explained powers the servo direct, then only the control signal comes from the RX.

Test this then you will have the evidence you seek.

G

wayneuk01

Some hitec servos eg 805bb require this set up depending on receiver type it does state if its a non b.e.c type then its ok to plug directly into the receiver would there be any advantage to using a y lead on a non b.e.c type receiver i beleave the specktrum i have (dx3) is a non b.e.c so pluging straight into the receiver is ok

glennb2006

The only issue there (may) be Wayne is the current carrying capacity of the internal PCB tracks that Dave alluded to earlier in the thread. The drawing you posted states that servo as pulling over 1 amp on full load.

Probably safest to go with the harness.

Glenn

rickburnout666

i`ve followed this thread for the short time that its been running, and have now tried 4.8 and 6 volts through traxxas , acoms and high tec recievers and no y piece was used and the 6 volt gives more power to the sevos, I connected scales to the servos, standard and high torque, more KG was pulled with 6 volts, which i thought would happen, 4.8V = 4 x 1.2V, 2000mah sub C cells, 6V=5 x 1.2V2000mah sub C cells , Batteries was all fully charged
I use a y piece on my Traxxas 1/5 scale buggy
to run 2, 1/4 servos off 1 channel (steering) and i use 1 standard servo for the throttle, all run with a 4.8 volt sub C cell battery pack

martno1fan

so this shows the y harness makes no diff to your rx then? if your getting 6 volts without one the y harness is pointless.

pete_486

they are right, when you feed direct voltage to a servo there is a genuine 6v and more amps, the signal wire only tells the votage what to do and does'nt need the extra power so the y lead does work................Pete

martno1fan

yea but if ricks tests show hes getting more power running through his rx and an old acoms at that when he uses a 6 volt pack instead of a 4.8 one surely the y harness is not needed?.if an old acoms rx doesnt reduce the voltage whats the likelyhood of the newer ones doing it?.

rickburnout666

I`m no expert in electronics but i did measure the difference , 2.5 KG with a high torque servo, and only 498 g with the standard servos,??
Wayne, I thought capacity and voltage of batteries are completely different things, Mah(capacity) is not voltage, but like i say i aint no expert,

rickburnout666

Mart none of the recievers are old, the oldest would be the high tec one but all give , the same readings on the scales , The Y piece might work, but it looks to me like you could save a couple of $`s or £`s and not bother with a Yuseless piece
I`going to try a brand new Cirrus 40 mhz 4 channel micro reciever and a month old Kyosho Perfex reciever to see how they come on the scales without a y piece and i will try with a y piece to see the difference, if there is one.
Catch you all later

wildchild45177

My Feedback: (11)

That's BS! The power is fed through the receiver on a bus. What ever is available at the receiver is available at the servo.

Bob

glennb2006

Except for voltage drop caused by the higher current through receiver PCB tracks that are not up to it.

And then you got BEC circuits on certain sets too.

Glenn

rickburnout666

Right done my tests with the scales, and with and without a Y piece, and there was no big differences using it and not using it, about .005 of a gram on 5 different recievers and using high torque,1/4 scale and standard servos, So to me i would have to say the Y piece power difference MYTH has been well and truely BUSTED. (in my house) The difference was probably caused by a difference in wire lengths
BEC`s i`ve used on elactric cars and boats to drop the power to the servos from 7.2 volts down to, i dont know what??
BEC Battery Eliminating Circuit, eliminates the use of, seperate 4.8 - 6 volt servo batteries