Tower hobby servos
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
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
breadboard jumper wrong. Fortunately, I had a 1K protective resistor on the
Stamp pin.
Thanks anyhow,
Ray McArthur
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
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?