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Tower hobby servos — Parallax Forums

Tower hobby servos

ArchiverArchiver Posts: 46,084
edited 2000-10-20 23:08 in General Discussion
I just purchased 2 cheap Tower Hobbies servos:
TS-53 STD-AIR TOWM4522

Apparently the -AIR means Airtronics connector.

We rigged a BS1 to operate through 90 degrees, 1 to 2 ms pulses.

It works fine with an old Futaba servo, but the Tower servos do nothing. I
assumed that the red wire is +5V, the black wire is gnd, and the white to be
pulse input, (the same color code as Futaba). A scope shows that the pulse
line cannot be pulled to gnd by the stamp, only down to +4V. The pulse line
is full swing with the Futaba servo. Do the Tower units have low input
impedance, or do I have it connected wrong?

Thanks in advance,
Ray McArthur

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2000-10-05 04:41
    Forget my last post. The Tower units work fine....these old eyes had a
    breadboard jumper wrong. Fortunately, I had a 1K protective resistor on the
    Stamp pin.

    Thanks anyhow,
    Ray McArthur
  • ArchiverArchiver Posts: 46,084
    edited 2000-10-20 13:33
    Your message is a bit old in the posting, but you caught my
    attention. Sounds like you have a 1K resistor as part of your servo
    circuit. I noticed in some of the Parallax Robots! curriculum, they
    indicate a 10k resistor as part of wiring the servo to the stamp, but
    in other places, they don't indicate a resistor (the servo is wired
    directly to the stamp and the power supply). Should I use a resistor
    with a servo?

    Thanks,

    Steve
    --- In basicstamps@egroups.com, "Ray McArthur" <rjmca@u...> wrote:
    > Forget my last post. The Tower units work fine....these old eyes
    had a
    > breadboard jumper wrong. Fortunately, I had a 1K protective
    resistor on the
    > Stamp pin.
    >
    > Thanks anyhow,
    > Ray McArthur
  • ArchiverArchiver Posts: 46,084
    edited 2000-10-20 23:08
    Steve:
    Ideally, you don't need any resistor. Since the servo control line, (white
    wire), is high input impedance, a 1K series resistor will not effect servo
    operation, but it will keep current to safe levels for the Stamp if you
    mis-wire or the servo circuitry fails.

    Regards,
    Ray McArthur
    Original Message
    From: <sjoblin@a...>
    To: <basicstamps@egroups.com>
    Sent: Friday, October 20, 2000 8:33 AM
    Subject: [noparse][[/noparse]basicstamps] Re: Tower Hobby Servos


    > Your message is a bit old in the posting, but you caught my
    > attention. Sounds like you have a 1K resistor as part of your servo
    > circuit. I noticed in some of the Parallax Robots! curriculum, they
    > indicate a 10k resistor as part of wiring the servo to the stamp, but
    > in other places, they don't indicate a resistor (the servo is wired
    > directly to the stamp and the power supply). Should I use a resistor
    > with a servo?
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