Servo SG90

Hi, I guess several people are using the SG90 servo. The docs I have state supply voltage 5V and signal levels of 5V too. Does it also work with 3.3V from a prop pin?
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Reinhardt

Comments

  • If the logic threshold is below 3.3v then I think it would.
    Windows 10 Home:
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  • If the logic threshold is below 3.3v then I think it would.

    That is what I wanted to know, because it does not work for me.
    --
    Reinhardt
  • ercoerco Posts: 19,484
    Well now I have to see if I have an SG90 servo. Of course, what's a "real" Tower Pro servo is up or debate. I buy a lot of dollar servos on ebay, and I'm pretty sure some of them have that sticker on them.

    I would think most servos should operate from a 3.3V control signal. What's the supply voltage to your servos, rbehm? Please don't say 3.3V...!
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • ercoerco Posts: 19,484
    edited 2019-07-23 - 21:05:23
    It sure should work. I took a cheapie servo tester running at 5V and split the control signal in half with a voltage divider (two 1K resistors), so it was only getting a 2.5V control signal. Again, mine is a cheap $1 Ebay servo marked "SG90", but it may be a clone (or yours may be a clone).

    Of course the servo was powered by 5V. As I already mentioned, don't expect a servo to run off of a 3.3V supply voltage. Also, servos need a LOT of current, so they need a hefty supply with lots of capacity. Often they are connected directly to the batteries, no regulator in between, provided the voltage is right (3-4 alkaline cells, for instance). A lot of people get burned by using old batteries. Always check your battery voltage, and don't use anything but new alkalines. Cheap "heavy duty" batteries at dollar stores are a joke. "Ideal for low-drain applications" = Stay Away!
    1440 x 2560 - 1M
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • You could use a 3.3V pin to drive a transistor to supply the 5V signal. I would use a 4.7 ohm resistor to protect my pin.
    Larry

    If the grass is greener on the other side...it's time to water your lawn.
  • rbehmrbehm Posts: 61
    edited 2019-07-24 - 14:01:58
    Ok, with a 2n2222 as a level shifter it works now.
    I am sure I had it working without that a while ago. Even two servos. But now it only works with 5V levels. Yes, I have taken care of adapting for the inverted signals.

    If I get hold of that guy who changed the laws of physics in my lab.
    --
    Reinhardt
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