URB unit

Free URB unit

I2C pullup resistors

The I2C bus needs resistors pulling the data line to a high potential. You can install resistors of any type on the board. I recommend 10K resistors. I also recommend the use of a smoothing capasitor 1000mf x 25V, when a URB connected to relay or servos, to avoid voltage drop when they turn on.

Asembling of the circuit by connection wires over the breadboard is a very inconvenient task. As the circuit becomes more complicated and the components added, problems are added with the correctness and reliability of connecting the wires and blocks. Therefore, I suggest you make a free URB unit that solves not only these problems but also adds new tremendous functions. You can collect a similar scheme on the breadboard, but URB is much more convenient!

This board uses Arduino NANO. Therefore, the dimensions of URBs are only 60x70 mm, which makes it possible to hide it even inside model building. This solution provides excellent flexibility, maintainability, simple mass production and low cost. The board is designed to avoid incorrect connection of Bluetooth modules and Arduino NANO.

To the functions of Arduino, the board (URB unit) adds the following capability:

  • Connectors for two Bluetooth HC-05 (HC-06) modules
  • Direct plug 3 servos or 3 sensors
  • Direct plug relay block
  • Direct plug motor-driver aka L298 or similar
  • Screw plug stepper motor
  • Convenient screw connections
  • 6 (7) High-Current outputs (Up to 0.4A per channel)
  • High-Voltage Outputs up to 50 V
  • Built-in I2C bus
  • Optional: install I2C pull-up resistors and smoothing capacitor for power supply


URB unit details

URB 2.X details
  1. PBS-15 (HO27): 2.54mm pitch PCB female single row 15 pin – 4 pieces (or 15 pin – 2, 6 pin – 2, 4 pin – 2).
  2. PLS-40: 2.54mm 40 pin male single row pin header connector – 1 piece.
  3. DIP IC Sockets 16P – 1 piece.
  4. 2 Pin screw PCB terminal block connector 5mm pitch – 12 pieces.
  5. ULN2003A (DIP16 package): High-Voltage, High-Current Darlington transistor arrays – 1 piece.

How get URB unit