Servos Big and Small (and Tiny) - For Eric (and anyone else interested)

[Smith H.]

Instead of sending this information just to Eric I figured I would share it with everyone.  The other night at the Inkscape rap session Eric joked about making his robot friend Bart (for short, we're buds) animated and I had mentioned that he could try these tiny servos that I had acquired in hopes to build an ultra light RC plane.  Not sure if any of you are familiar with servos so here are some pictures of a few that I had on hand and some information about them.

Size

For this I'll just let the pictures do the talking:

    Top to bottom:  38g Standard Servo, 9g Micro Servo, 1.7g ULTRA MICRO Servo, 4-ch receiver for the ULTRA MICRO servo.

Torque

The first (largest) one I have is a 38g standard servo capable of 3.8kg-cm @ 4.8v, 4.3kg-cm @ 6v of torque.  Pretty crazy right?

The next smaller one is a "micro" 9g servo which should be capable of about 1.5kg-cm of torque at 6v so a little less if the voltage is less.

The tiny one is a 1.7g ULTRA MICRO servo which is capable of 50g-cm @ 2.8v and 75g-cm @ 4.2v.

Speed

The Standard servo rotates 60-degrees in .21 or .17 seconds depending on the voltage above (faster with more voltage).

The 9g servo does the same rotation in .12 second at 6v, I would estimate .16 at 4.8v.

The ULTRA MICRO servo does the 1/6 turn in an astounding .07 seconds or .05 seconds, again depending on voltage (see the two voltages above).

Connections

The Standard and 9g servos have standard servo plugs (female) JR connectors.  

The ULTRA MICRO servo has a micro JST plug (female) with a 1.25mm pitch (spacing between pins - this is important because there are only a few RC receivers that can accept this pitch [or so I believe]).

For robotics though you would probably remove the connectors anyway and solder them into your project directly.

Cost

The Standard ones are about $4 a piece.

The 9g ones can be had on Amazon for about $2 ea. if you buy a 10-pack.

The ULTRA MICRO servos are only about $3.50

Experimentation Opportunities

So, as I was writing this post I started to wonder what would be done by wiring an RC Receiver to an arduino's inputs (analog I suppose) and being able to translate transmitter inputs into Arduino outputs to both motors and other things.  I'm still getting into the Arduino world but this sounds like fun to me.

I was going to try to make it tonight, but can't.  Is anyone else interested in the possibilities of using an RC Tx/Rx as an input device to an Arduino project.  I'm sure that you could theoretically code your own flight controller for an airplane, but I'm thinking DRONE PAINTBALL TANK with AUTO-TARGETING.  Clearly that would require a few of the larger servos and some DC motors to drive the treads.

Smith H.

[Smith H.]

Here are some links to see more about these: No affiliations; I ordered the 38g and 1.7g servos from Hobby King, the 9g and the receiver from Amazon (or a seller thereon)

38g: https://hobbyking.com/en_us/hobbykingtm-hk15138-standard-analog-servo-4-3kg-0-17sec-38g.html

9g: https://hobbyking.com/en_us/em-micro-servo-blue-9g-1-5kg-12sec.html

1.7g ULTRA MICRO: https://hobbyking.com/en_us/hk-5320-ultra-micro-digital-servo-1-7g-0-05sec-0-075kg.html

Receiver in the picture (For Spektrum Radios): http://www.altitudehobbies.com/orangerx-r415x-dsmx-dsm2-compatible-4ch-micro-2.4ghz-receiver

[David S Flores]

Great info! Thanks!!!