Breyta servó þannig að það ferðist 180° í staðinn fyrir 60°

[Sverrir]

Athugið að hér er verið að ræða um Futaba S148 servó en þetta má samt nýta sér á fleiri servó að teknu tilliti til sérkenna þeirra.

The way the servo senses the output arm position is by using a potentiometer tied to the output shaft. It uses this pot as a voltage divider. Say there is 5 volts across the resistance element, then when the arm is centered it has the "Wiper" at the 2.5 volt point on the resistor. 45 degrees CW could then be 3.75 volts and 45 CCW would be 1.25 volts.

These numbers are not necessarily what it gets, just examples to give you the idea.

To increase the angular travel we have to fool the control, and give it these numbers at a greater angle, and it's easy to do.

Have you ever replaced the pot in a servo? Or taken one out to clean it? If yes then you know how to get into it. We don't have to take the pot out for this, just add resistors in place of the wires to the ends of the resistor in the pot. The more resistance added, the greater the travel. up to the mechanical limit of the servo. Most have a mechanical limit around 200 degrees.

Looking at the pot you will see three connections, with one pretty much in the middle. Leave the middle one alone, disconnect the other two. Using your DVM measure the resistance of the pot, most are 4 to 5K ohms. This is the approximate amount of resistance needed to double the travel.

The Futaba S148, as near as I remember, took a 1.8K on the left leg looking from the wire exit end, and a 2.3K on the right. You can start with these values, you may have to increase or decrease, you might end up with the same amount on both sides. By shifting more to one side and less to the other, you center the travel.

It is not necessary to assemble the servo for a travel check. If you have left the gear train assembled hook it up to a radio or servo driver, see what you have. If the gear train is off set the transmitter or driver control to full travel one way, turn the pot until the servo motor stops running, then put the tx to the other end, and again play with the pot until the motor stops. If you turn the pot too quickly doing this the motor can reverse its direction very quickly. Turn the pot slowly, as you approach the neutral position the motor will slow down.

Go to Radio Shack, you can get a 100 pc assortment of 1/8 watt resistors, should give you enough variety to find what you need, and do several servos. For future ones you will know which ones to buy, no need for the assortment.


Mæli líka með því að þið lítið á þessa slóð hérna > http://mypage.yhti.net/~dmcdnld/s148retract.htm < en þarna má sjá myndir ásamt nánari leiðbeiningum.