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Inexpensive Servo Point Motors

Entries in this blog

Preventing Servo Buzz

A 90 degree servo shaft rotation is highly appropriate for driving the ailerons on a model aircraft. The motion produced at the aileron through a crank linkage will be proportional to the rotation of the servo shaft, but if the servo were to even approach 180 degrees of rotation, the motion would no longer be proportional and the mechanism would tend to lock.   In the case of points, we don’t really care about proportional motion. In fact, if we can make the servo rotate through 180 degrees an

AndyID

AndyID

Interference and Buzzing

Interference and Buzzing   Based on what I have seen, I believe the “going bananas” problem and the “buzzing” problem result from two different effects. The first is caused by electromagnetic interference/radiation (EMI/EMR) and the second is more commonly to do with the mechanism that transmits force and motion to the point tie-bar. Unfortunately, if we are not careful, in trying to solve the one, we might make the other worse.   From the description of how the servo controller chip works,

AndyID

AndyID

Servo Operation

The SG90 is a PWM (Pulse Width Modulation) controlled servo, so the width of the pulses applied to its control input determine the position that the internal controller drives the servo to. Pulse widths are between 1 and 2 milliseconds, and are applied every 20 milliseconds (50 pulses per second). The servo assumes a nominal center position when the pulse widths are 1.5 milliseconds. The nominal extremes of position are plus and minus 45 degrees at the maximum and minimum pulse widths (1 and 2 m

AndyID

AndyID

Low cost servo point motors

I was not sure whether to post this as a topic or a blog. As it's probably going to be a bit "long winded", I thought a blog might be best - so here goes!   Like many others I have been messing around with servos to control the points on my OO layout. In the process I've discovered a few things that might be helpful to others who plan to do something similar. There are some advantages associated with using servos, but there are also some challenges that must be addressed to obtain the most rel

AndyID

AndyID

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