Nice Cheap Servo for Continuous Rotation Modification

erco

Senior Member
I'm building one or two small mobile robots each week for work (I love my job!) and I've been modifying several different cheap standard-size servos for continuous rotation. Some are easier to mod than others, some have better fine motor speed control. This week's favorite is Hobby King's Turnigy TGY-S4505B .

1) It's cheap, $5.10-$5.65 USD depending on Int'l vs US warehouse and if you wait to order (discount offered)
2) Dual ball bearings for long life
3) Doesn't need the internal pot for support. Just snip off the plastic pot shaft and it's mechanically disconnected.
4) Snip a single post off the output gear for 360 degree rotation
5) Unsolder 3 pot wires (note color, they vary) and route thru a hole in the case to an external 5-10K trimpot.
6) Excellent center stop stability
7) Excellent fine speed control, wide PicAxe SERVO command range: 90=max ccw--125=stop--195=max cw
8) 1.75" diameter circular servo horn included makes a fine free instant wheel, just cut a rubber band "tire" out of an old road bike innertube.

It uses nylon gears, so don't overload it, but I was pleasantly surprised how well these work. I hate re-nulling drifty CR servos every other day, and I don't have to with these. A five-star thumbs-up, I'm ordering more.

Edit: Servos driving 1.75" servo horn "wheels" at 6V (4xAA) gives maximum forward speed of ~7"/sec.
 
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techElder

Well-known member
erco, I noticed it has a "carbon brushed" motor. Is that a disadvantage in your view?

PRODUCT ID: TGY-S4505B
Spec.
Type: Anolog
Gear train: Plastic
Bearings: Dual
Motor Type: Carbon Brushed
Weight: 40g (1.41oz)
Lead: 30cm
Torque: 3.9kg.cm @ 4.8v / 4.8kg.cm @ 6v
Speed: 0.13sec 60°@ 4.8v / 0.10 60° @ 6v
 

erco

Senior Member
Carbon brushes are a step up from the metal brushes used in the cheapest brushed motors. So for a cheap servo in light use, I think it's fine.
 
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