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Miscellaneous Robot Electrical Parts and Materials

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  • Miscellaneous Robot Electrical Parts and Materials

    Answers to questions about Miscellaneous Robot Electrical Parts and Materials.

  • #2
    Originally posted by FTC8397

    Subject: Use of Camera Flash/Flashlight Allowed

    Question: Will use of the Camera Flashlight be allowed during the 2019-20 season? It can be helpful with computer vision tasks. It was allowed during the 2017-18 season. For 2018-19, it was initially disallowed, but that decision was changed, and it was ultimately allowed during 2018-19. Thanks!

    Answer: Yes
    Last edited by Pierluigi Collina; 09-18-2019, 01:59 PM. Reason: update formatting


    • #3
      Originally posted by FTC12090
      GoBilda Battery

      Q: Is the goBILDA 12v battery pack using the same cells as the Tetrix and Rev Robotics battery pack in an offset cell layout for spacing going to be allowed this year?
      A: No, the only legal batteries are those listed in Rule <RE03>


      • #4
        Originally posted by FTC16072
        Subject: COTS LED Module Legality

        Question: Sparkfun has an I2C controller for LED strips that also has some LEDs built-in:
        ( code here for other FTC teams: )

        According to GM1, <RE12C>

        Technically this has a programmable micro controller on it (ATTiny85), BUT it is not designed to be programmed in the circuit and we are not programming the chip. (ie, we are using what it comes with which is a simple program that accepts I2C commands and uses those to select which lights to light up with which color.

        It feels to me that this is within the spirit of the rules since it isn't designed to be user programmed (and we aren't programming it)


        Answer: Yes. Most of the LED interface boards and intelligent sensors have some sort of processor in them. As long as the processor is not user programmable, the part is allowed (if it does not violate other rules)
        Last edited by Pierluigi Collina; 09-26-2019, 02:13 PM.


        • #5
          Originally posted by FTC4634
          Subject: LED Clarification

          Question: <RE12-A> States "Focused or directed light sources (for example: lasers and mirrors) are not allowed except for the REV Robotics 2m Distance sensor (REV-31-1505)". Would using LEDs or an LED strip inside a Robot for illumination of Game Elements possessed by the Robot in order to aid with computer vision be considered "focused" or "directed"? Given that the phone camera flash is allowed, we're assuming this would be fine, but just wanted to double check.

          Answer: focused or directed in this context is refering to the use of lenses and/or mirrors to concentrate or direct the light in directions that it would not travel naturally.


          • #6
            Originally posted by FTC14188
            Subject: Solenoids

            Question: Are electromagnetic solenoids allowed?

            Answer: No - they fall under <RE17> and are not allowed


            • #7
              Originally posted by FTC16072
              Subject: Connector Converter Made from Custom PCB

              Question: In <RE17> it specifically says that custom circuits are not allowed. However, can we make a printed circuit board (PCB) that has no components besides connectors? (For example - to convert from one type of connector to another in a way that is less error prone than making our own cables.)

              Answer: Yes. Care should be taken to make sure all connections are appropriately insulated. Be prepared also to describe/discuss/provide details about the connector conversion board with the robot inspectors at your events. It might be helpful to have an extra or two without covering insulation to be able to show


              • #8
                Originally posted by FTC12991
                Subject: Power Disconnect
                Question: The team desires a master power disconnect between the battery and approved Rev power switch to open both sides of the battery power during test and construction with out having to disconnect the battery. They want to use a receptacle and looping plug made out of Anderson Powerpole parts (See HS-4 and PL-4). Is this master power disconnect acceptable as long as everything downstream of the disconnect meets the appropriate rules?

                Answer: There is nothing in the rules that would prohibit this. This is equivalent to making/extending leads for the battery connection. Make sure to use appropriately color-coded wires of the correct minimum gauges. Be prepared to explain/demonstrate the intended usage to the robot inspectors at your events.


                • #9
                  Originally posted by FTC7854
                  Subject: LEDs with I2C/SPI Bridge

                  Question: I'm looking to add a controllable RGB light strip to the outside of our robot for aesthetics and for signaling purposes in TeleOp and Autonomous to the drive team. I've found Adafruit's DotStar LED strips which accept a 5V input and SPI control ( and a non-programmable I2C to SPI bridge module ( I would connect the light strip to the SPI bridge module (SCK, SS0, 5V and GND), then from the module the I2C communication channels to an I2C port on the REV Expansion Hub and the 5V and GND to an auxiliary 5V port on the REV Hub since the I2C ports only supply 3.3V. I have two questions: Are these acceptable electronic products? They seem to abide by the COTS non-programmable electronics rule and LED light strips have been generally accepted in the past, but I wanted to double-check. Also, do I need to connect the ground of the SPI bridge module to both the REV auxiliary 5V port and the I2C port, or would wiring the ground of the bridge to just the auxiliary port be enough? (SDA, SCL to I2C and 5V, GND to 5V auxiliary)

                  Answer: Yes. The combination you describe would be allowed under the current rules. If you are unsure about the wiring of the devices, we would recommend contacting the manufacturers/sellers for advice.


                  • #10
                    Originally posted by FTC1999
                    Subject: Multi-Conduction Wiring

                    Question: Would my team be allowed to use multiple parallel wires of a smaller gauge that when combined, equal or exceed the same cross sectional area as required by <RE14>j, since this would achieve the same outcome?

                    Answer: No. All wires used in an electrical connection must meet the minimum wire gauge requirements for the connection.


                    • #11
                      Originally posted by FTC16461
                      Subject: Alternative Battery Packs

                      Question: The Modern Robotics battery listed in <RE03> is currently out of stock:
                      b. Modern Robotics/MATRIX (14-0014) 12V DC battery pack (

                      The TETRIX battery is a similar form factor, so it could work as a replacement, but it is considerably more expensive:
                      a. TETRIX (W39057, formally 739023) 12V DC battery pack

                      Is it possible that the Gobilda NiMH Battery (12V, 3000mAh, XT30 Connector [MH-FC], 20A Fuse, 12-20) could be added to the allowable list this year? It matches cell count, mAh and fuse with the other batteries in the list.

                      Answer: The only batteries currently allowed for FIRST Tech Challenge are those listed in Part 1 of the Game Manual.


                      • #12
                        Originally posted by FTC8397
                        Subject: Connectors for DIY Power Splitters

                        Question: We are using two Rev Expansion hubs, a Rev Servo Power Module, and a Rev Resistive Grounding Strap. We plan to use a splitter to connect from a Rev Expansion Hub to both the Servo Power Module and the Resistive Grounding Strap.

                        From Game Manual Part I, <RE14>e states: "Power distribution splitters are recommended where appropriate to reduce wiring congestion. All connectors and distribution splitters should be appropriately insulated."

                        We would like to make our own "Y"-shaped splitter with XT30 connectors on all limbs, and limbs connected with either:

                        a) Appropriately-sized wire nuts (wrapped with electrical tape or shrink wrap), or
                        b) Appropriately-sized crimp connectors (also insulated with electrical tape or shrink wrap)

                        Would these approaches be allowed?

                        Answer: Both mentioned connectors are allowed when used appropriately (i.e. appropriately sized for the wire gauge and well insulated)


                        • #13
                          Originally posted by FTC16031
                          Subject: Voltage Converters

                          Question: Can we use a voltage converted something like this one ? We noticed that the Gobilda servo has different RPM on different voltage, for example, on 7.0 voltage , the servo can run 60 rpm instead of 50 rpm.



                          Answer: No. Voltage converters fall under RE17 and are not allowed.


                          • #14
                            Originally posted by FTC14423
                            Subject: Wire Color Conventions
                            Question: RE14(g) says: Power and motor control wires must use consistent color-coding with different colors used for the positive (red, white, brown, or black with a stripe) and negative/common (black or blue) wires.

                            At our tournament today, our inspector suggested that we ask about this rule for clarification. We use 6 wire coils for our lift. Our motor extension wires as part of the bundle are black and red to match our motors. Our other cables, however, do not match the servo wire colors. We just want to make sure that this is not a problem. We have presumed not, because the leading servo extension cables are a different color than the wires that come on most servos.


                            Answer: Use of a color convention does not require matching colors between connected wires, just a consistent use of the colors that exist.