Hi friends

When I plug the servo into one of the channels the servo starts to jitter 30 degrees each side.
Now Ive been trying to change the channels or servo but still it jitter.
When I take it off the EQ 10 and plug it directly to the RX the jitters are gone and it works good.

When I connect all servos as well, they ALL jitter too.

Batteries Fromeco A123 2300 fully charged all the extensions are checked as well.

What can it be ?

Thanks,

Adi

Hi Adi,
Are you running the servos directly from the Fromeco batteries (no regulators?). If so, this is a common problem where the servo is not recognizing the control pulse correctly since the servo voltage is so high. Please give me more details of your setup so we can help with this. I am positive this is not an Eq10 problem but a servo/voltage problem.

Hi Richard

The batteries are going in a direct line into the EQ 10.
The servos are Hitec 7955 TG.
The batteries are A123 6.6 V.

Thanks,

Adi

We have attached a Sahara Regulator and made it 6.1V and the jitter stopped.
This is strange since we have here a few guys, including me that has EQ 10 with A123 Batteries and NO regulators with no problem at all.

What do you think ?

Hi,
I think this all depends on your servos. The bigger the difference between the signal voltage going to the servo (typically 3.3V, some Futabas are 2.7V) and the servo power voltage the more likely you are to see jitter. The reason is rather technical but basically it depends on the type if signal input buffer the servo uses. The servo manufacturer should use a "TTL level" compatible buffer but a lot are using "CMOS level" compatible buffers. A TTL level buffer always recognizes a "high" signal level above 2.4V. A CMOS level buffer only recognizes a "High" signal level when the signal is at least 80% of the buffer Vdd. This means if your servo has a CMOS signal buffer and your servo power voltage is 7.2V then the signal voltage has to be at least 5.75V, no receiver or power system drives a signal this high. Basically, all the servo manufacturers are breaking the rules that have guide servo design for the last 30 years. Unless us modelers call them on it things will only get worse.

With all that being said, if I am using Hitec 7955 servos not high voltage, that is a common thing ?
With which servos it is not suppose to happen ?
I just love your products and for that i am willing even to change my servos !

And why the regulators fixed that thing ?

Hi,
Its really hard to tell which servos will work and which will not. I cannot keep up with all the servos that come out. Normally the Hitecs work OK, not sure why yours do not in this case.

The regulators fixed it because the difference between the voltage level of the control signal (3.3V) and the voltage the servos are running on was reduced. This allows the signal receiver in the servo to see a higher percentage of the total voltage and it is now recognizing a signal "high" accurately. (3.3V/7.2V = 45%, 3.3V/6.1V = 54%). Ideally all servos would recognize anything over 3.0V as a true "high". This was the standard, by default, for 30 years.

What rx?

Originally Posted by rrritchey

Hi,
I think this all depends on your servos. The bigger the difference between the signal voltage going to the servo (typically 3.3V, some Futabas are 2.7V) and the servo power voltage the more likely you are to see jitter. The reason is rather technical but basically it depends on the type if signal input buffer the servo uses. The servo manufacturer should use a "TTL level" compatible buffer but a lot are using "CMOS level" compatible buffers. A TTL level buffer always recognizes a "high" signal level above 2.4V. A CMOS level buffer only recognizes a "High" signal level when the signal is at least 80% of the buffer Vdd. This means if your servo has a CMOS signal buffer and your servo power voltage is 7.2V then the signal voltage has to be at least 5.75V, no receiver or power system drives a signal this high. Basically, all the servo manufacturers are breaking the rules that have guide servo design for the last 30 years. Unless us modelers call them on it things will only get worse.

SMART-FLY Is the best system out there, I have many of them, and one of my servos jitters , but after reading/learning what you said I will change it to 6.1 or 6v thats pleant.

Guys this is a very clear example of why you should run Smart-Fly systems, cuz the owner knows his stuff and supports his products 100%. I will never run a 50cc or larger with the support of Smart-Fly. Just try getting this support from powerbox/wetronics ya right. Ya right !!

Robert thanks allot for the clear answer.
From now on I'll put regulators on mine.
Is this jitter can happen when using Nicd 5 cell as well ?

ddlstang it was JR R921 2.4Ghz

Hi,
If you get jitter with A123 batteries (which charge to a maximum of 7.2V) then you will probability get jitter on 5-cell NiCd/NiMH also. The NiCd/NiMH will drop to a lower voltage faster than the A123s which will drop to 6.6V and hold there. It used to be very common to get a little servo jitter with 5-cell NiCd/NiMH packs at full charge but this would go away pretty quickly as the packs dropped.

Thank you for your help Adi! I appreciate you my friend!