3. Parts List & Overview

The T-RECS is composed of several components that students are provided in the form of a kit. Depending on your instructor, some of the components in the kit may be pre-assembled or already soldered for you. The kit will contain the following components:

Complete Parts List

  1. Propellers

  2. Ball Bearings

  3. USB cord

  4. Motor Clip and Stopper

  5. Hardware (see detail below)

  6. Printed Circuit Board (PCB)

  7. Raspberry Pi Pico and Adapter

  8. Power supply

  9. Brushed motor

  10. Laser cut wooden parts (see detail below)

Laser Cut Wooden Parts

  1. A, B, C, D - Tower walls

  2. E, F, G, H - Tower Sides

  3. J, K, L, M, N - Base Components

  4. O- Tower Connector

  5. P- Arm Stopper

  6. Q, R, S, T - Arm Components

Hardware List

  1. Motor Stopper

  2. Motor Clip

  3. Shaft with Arm

  4. Shaft only

  5. M4 Nut

  6. M4 x 20 Screw

  7. M3 Screw (4 pieces)

  8. M3 Standoff (4 pieces)

  9. M3 Nut (4 pieces)

3.1 Electrical Components

3.1.1 Brushed Motor

The T-RECS is propelled by a brushed DC motor. Brushed DC motors possess 2 simple input terminals (positive and negative).

3.1.2 Printed Circuit Board (PCB)

Most of the system’s electronics are housed on a printed circuit board (PCB) to keep the wiring and circuitry simple and unobtrusive. The circuit board features a microcontroller, a transistor for controlling power to the rest of the system, a rotary position sensor for measuring the system’s pitch, and several receptacles for connecting the necessary wires to the board. Wires to be connected are the barrel jack, the wires that connect the motor to the PCB and the USB to connect the microcontroller to the computer.

3.1.3 Microcontrollers

There are several types of microcontrollers that will work with the T-RECS. Worldwide availability may determine your controller, or you may have the option to pick your own. Some T-RECS systems may come with an adapter as availability of microcontrollers changes over time.

  • Raspberry Pi Pico (RPi) - The current version of the T-RECS uses a RPi Pico with an adapter. The Pico can unplug from the adapter, which can also unplug from the PCB. The Raspberry Pi Pico has plenty of storage to run programs. For the T-RECS, the RPi will NOT have a program (firmware) already loaded on it.

    • You will need to update the firmware which can be found at www.tangiblesthatteach.com/downloads. Hold the button on the RPi down while plugging it into a computer. Once plugged into the computer, release the button. The Raspberry Pi will show up as a drive on your computer, and you can drag and drop firmware onto it. Once loaded, the drive will "disappear" from your computer. That's all there is to it!

  • ESP32 - this microcontroller will be an available option in the future, with plenty of storage to run programs and WiFi capabilities. WiFi capabilities may be limited on LAWN systems. More to come on this microcontroller.

  • Arduino Nanos have been used in the past with the T-RECS system, but are not currently supported.

3.2 Mechanical Components

The mechanical structure of the T-RECS is composed of four unique components that are manufactured via 3D printing and laser cutting. These parts are a single base, two towers, two shafts, and one arm.

3.2.1 Base

The base serves as the anchor point for the system.The base should always be clamped down or securely fastened to a solid flat surface such as a table or workbench whenever the system is running. The base should be oriented such that the arm hangs off the edge of the table, free of any obstructions that could interfere with the propeller.

3.2.2 Towers

The two towers are not designed to be identical so that they can only attach to the base in the correct configuration. In addition, each tower has different hole configurations for different attachments. One tower is designed to house the T-RECS PCB and one tower has hole configurations to allow for an encoder (a future add-on). The towers feature a protective overtravel stop at both the high and low end to prevent the arm from going past about 80° above horizontal and -30° in the event of a malfunction or improperly tuned controller. Both towers contain bearings for supporting the necessary low-friction rotation of the arm. The left tower is intended for mounting the PCB based on the PCB’s design and wiring of the system.

3.2.3 Shafts

The shafts connect the arm to the bearings in the towers and one shaft mates with the rotary position sensor the T-RECS uses for measuring its pitch. A secure fit is required between the shaft’s square peg and the arm and between the shaft’s semicircular dowel and the sensor to ensure reliable measurements. Some sanding may be necessary in order to insert the shafts into the arm and the position sensor.

Troubleshooting tip: sometimes "play" between the shaft and the position sensor can cause noisy readings. To fix this, use pencil lead or a small piece of paper as a shim.

3.2.4 Arm

The arm is the dynamic component of the T-RECS. It houses the motor on its free end, which is mounted securely on a clip and motor stopper screwed to end of the arm.

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