General Information
Created for a certain type of XRT owner, and while we don't know you, this one's for the hooligans.
Direct Power:
The DP in the model number means this servo requires Direct Power. Anyway, this means it uses a 2S-4S pack. While we have them in capacities ranging from 650mAh to 6000mAh, the most popular pack is the B4S2500 and if you want one, then remember to add it to your order. Or select it from the pull-down menu under Power Options. Anyway, whether you buy a pack from us, or not, just so you know, the 2500 is the most popular size, and it uses an XT30 - keep this in mind. Meanwhile, the DuPont (the connector used for signal from the receiver) gets it's power from the receiver to operate the logic circuits and this voltage may range between 5-8.4VDC.
Also, if you have other ideas for powering the power section, like maybe using a stand-alone BEC, perhaps a Castle Creations CC BEC 2.0 or similar (we have these, also), it's unlikely to have the stones to run the servo at full power.
Or if in the alternative, you're thinking of just tying into the propulsion pack, instead (maybe by tapping into two cells via the balance connector), then please be aware ripple (electronic noise) due to the motor/ESC (as it varies throttle position) will backfeed into the circuit (on the servo) and damage a component on the PCB. We're expressly warning against doing this so you know in advance that repair cost won't be covered by warranty. Not trying to be an asshat, but also don't want this to become a problem, so heads up, eh?
Servos are not designed for people to zing-zing them back and forth using a servo arm. Doing this may damage the gear train. Reason being, the transmission is comprised of gears designed to take the force of a weak motor, multiply it many times until we get to the final drive ratio. Way it works is individual gears are designed so that a small pinion drives a larger bull. This happens in a ratio ranging from 1:3 to 1:6 through a series of combo gears to reach the final ratio, which can vary from 1:150 to over 1:500.
Thus, grabbing the servo arm and moving it back and forth isn't just driving it backwards at 3:1 or 6:1, but far worse because you're really driving the servo motor through the entire transmission's gear ratio, which for the DS1885BLDP-M is 155:1. Means the risk is you're going to break something if you persist!
Note1; that you do it all the time with other servos is your business, but you shouldn't. Anyway, with our servos it becomes our business 'if' you ask for warranty. Reason being, once we see the teeth have been damaged (and we will), then because the servo cannot drive the gears enough to drive damage them, this means the damage came from an external force input, e.g. you grabbing the servo arm and moving it back and forth. Since we're not stupid, it's not a warranty issue.
Note2: gently moving them, e.g. returning a control surface back to center, or when folding a helicopter's main rotor blades into the holder won't damage anything.
Bottom line? If you like to zing-zing the servo back and forth using the servo arm, don't. Stop driving servos backwards, they're not meant to be driven externally! Not ours not anybody's.
The DS188BLDP is made for an X-maxx and the -M version fits the XRT but to save you time, review this info for if you're curious because some of it may help guide you in your quest.
Q. I'm looking at buying the DS1885BLDP for my XRT. What is the power options all about? I am not sure what to select.
A. The DS1885BLDP servo is equipped with two connections instead of one. Reason for the second is due to being unable to make power out of thin air. Basically, when we get to this class of servo (the stock servo makes about 350oz-in vs 1885oz-in), then to keep from;
a) overwhelming the ability of a lands of the receiver's PCB to handle the current draw, and
b) the capability of an ESC's BEC circuit to create sufficient quantities of current, we resort to a trick.
We simply power the servo's control electronics (via the usual little black DuPont connector used for servos) by whatever powers the stock servo, and then we feed the servo motor with a dedicated source via an XT30 connector. So the servo has a 20AWG lead with a DuPont connector like usual, plus one more lead, a heavier one we quipped with an Amass XT30.
As for the source (a 4S battery pack), we offer two. One's small offering 850mA of capacity and the other (larger) outputs 2500mA, instead. The smaller one principally because there are some who heat race their rigs. These folks benefit from the lighter weight of the small pack. Most bashers get the larger pack.
And by way of heads up, please don't make the mistake of thinking, 'I can just tap into one of two propulsion packs to get the 4S power!' Please don't. We thought of that and what happens is because of ripple and noise created by the motor/ESC, the circuit within the servo gets damaged so it's not a good approach. Anyway, because we can readily identify this as the source of the damage, we won't cover it as a warranty repair.
Finally, if you haven't come across it, this video by a customer may help.