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Robot Electronics and Power - Answer Thread

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  • #91
    Servo Reverser?

    Originally posted by FTC6448
    My team needs to hook up two servos to the same channel, but have them turn in opposite directions. Is this an allowable part to use to invert one of the signals?

    Thanks for your help!

    A: No. The above part is not allowed.


    • #92
      Spiral Telephone Cord Legal?

      Originally posted by FTC5694
      Are we allowed to use spiral telephone cable/cord?

      A: Yes, as long as no other rules are violated. Pay attention to wire gauges.


      • #93
        Originally posted by FTC3550
        Please clarify rule <R03> k. 2. and what "provided no other rules are violeted" really means.

        If a part on the sensor is integral to the sensor's function, is the part allowed? i.e. the encoder disk of a rotary encoder assembly, the lens of an imaging sensor, the plastic shroud on a color sensor, et al.
        (, respectively)

        Or, are these parts dissallowed per rule <R02> a?

        Thank you for the clarification!

        A: parts that are integral to a sensor's function are allowed as used in conjunction with the sensor via the sensor prototype board


        • #94
          Coiled CAT5 Cabling

          Originally posted by FTC3415
          Would coiled CAT5 cable be allowed as per rule R03.O.3-4?

          A: Yes, as long as no other rules are violated (pay attention to wire gauges)


          • #95
            Coiled Cables

            Originally posted by FTC3539
            Since phone cords were allowed in a previous post, i want to double-check whether we can use the following part for motor leads:

            Neoprene Rubber Jacket Retractile Cord Black, 300 VAC, 18/7 AWG, 2' Retracted
            McMaster-Carr Part number: 7088K83

            This complies with Rule <R03>o.3. about motor control leads being 18 gauge or higher, but is the coil an allowed COTS (under wire management <R03>q.)?

            A: Yes, the above cable is allowed. Make sure to pay attention to wire gauges.


            • #96
              Extending NXT wires?

              Originally posted by FTC6209
              We have force sensors on the end of our ring manipulator so that we may differentiate between weighted and non-weighted rings. Unfortunately the longest official NXT wire does not reach the length that we require. Is it acceptable within the rules to connect the force sensors to the NXT brick using a spiral telephone wire. Additionally how would the 90mm length regulation apply to this clarification. We would also like to clarify the specific wire gauges allowed for that specific function.

              A: NXT cables may not be modified legally.


              • #97
                Decorative LED's

                Originally posted by FTC5096
                We would like to use decorative LEDs on our robot powered by a single 9v battery. The LEDs serve no functional purpose. They will be manually turned on when the robot is placed on the field and turned off at the end of the round. Would the following controller be allowed to adjust the color of the LED strip? It is our intention to select a color when the LEDs are turned on. The LED color will not be changed during a round.


                A: Yes. The listed LED part would be legal, as long as no other rules are violated


                • #98
                  Metric Equivalents for AWG wire specifications

                  Originally posted by FTC5110
                  <R03>o specifies wire gauges in AWG. In the metric world there are no exact equivalents to AWG sizes. Is it permissible to use closest metric wire gauge to AWG? Specifically <R03>o.4 has only 20AWG or 22AWG listed.
                  Thanks! FTC5110

                  A: Yes, it permissible to used the closest metric wire gauge, as long as the area of the metric wire is not smaller than the AWG wire equivalent (i.e. round up to the larger metric size when an exact equivalent isn't available)


                  • #99
                    PWM Cabling &amp; Shielding

                    Originally posted by FTC5110
                    <R03>o.4 permits use of 20AWG or 22AWG wires for PWM cables.
                    1.) Is it permissible to use multiple individually insulated wires in parallel to essentially increase the overall wire cross section? The initial "split" is covered by <R05> and <R03>o and using a stock TETRIX servo Y cable for re-combining at the far end thus it seems logical custom cables manufactured with parallel wires are acceptable.
                    2.) Can a cable with shield be used provided the conductor cross section does not exceed 20AWG? Electrically this would be connected to the Black wire at one end of the cable.
                    3.) If shielded cable is not permitted as per 2.) is custom shielded cable manufactured using adhesive aluminium tape, as permitted in <R05>, or plain aluminium foil, as permitted in <R02>d.1, allowed.
                    Thanks! FTC5110

                    A1: There is nothing in the rules that would prohibit this
                    A2: Shielded cable is allowed. Connecting the shield to ground would not be allowed
                    A3: Custom shielding would be allowed, with the same constraint as A2, i.e. no connection to ground.


                    • Laser diode legal?

                      Originally posted by FTC3539
                      Can we use an ER55L 675nm 20mW Red Line ER 55L Laser Diode with Adjustable Focus powered by a 9V battery and controlled by the protoboard through opto-Isolators? You can see the specs at ?

                      A: No. Laser diodes are not allowed.