IOT123 - 3.3V POWER BRICK

About: The tension between novelty and familiarity...

Intro: IOT123 - 3.3V POWER BRICK

The IOT123 BRICKS are DIY modular units that can be mashed up with other IOT123 BRICKS, to add functionality to a node or wearable. They are based on the inch square, double-sided protoboards with interconnected through holes.

Although the instructions relate to a semi-permanent bond between the BRICKS, the male pin joiner described here can be swapped for a pair (male on consumer/female on provider) of header pins for easy assembly. Also the pin contract (position and meaning of interconnecting pins) relates to the ATTINY85 NRF24L01 BRICKS, but can be modified to suit any other IOT123 BRICK contract.

The power input is expecting 5V DC through the MicroUSB socket, which is smoothed/cleaned with capacitors and is output as 3.3V with an AMS1117 regulator. A switch is sandwiched between the 2 PCBs and the +ve/GND pin are exposed for consumption by other BRICKS.

Step 1: Tools and Materials

    There is a full Bill of Material and Sourcing list.

    1. Micro USB Breakout (1)
    2. AMS1117 SOT-223 (1)
    3. SPDT Side PCB Switch (1)
    4. 1" Double sided protoboard (1)
    5. 10uF Tantalum Capacitor (2)
    6. 100nF Ceramic Capacitor (2)
    7. Male Header (5P)
    8. Female Header (2P, 2P, 2P)
    9. Hookup wire (~6)
    10. Solder and Iron (1)
    11. Strong Cyanoachrylate Adhesive (1)

    Step 2: Circuit Assembly

    1. Add the 5P male header to the Micro USB Breakout with the plastic collar on the same side as the socket.
    2. Insert the power pins (1, 2) and a support pin (3) (male pins with long end pointing into the PCB) into the bottom of the BRICK to be powered.
    3. Place POWER BRICK PCB over the male pins, with bottom facing up. Solder off on bottom.
    4. Detach BRICK to be powered from POWER BRICK and put aside for the time being.
    5. Depending on what you have, the SPDT may need to be trimmed of tabs/pins leaving 3 pins on one side only.
    6. On the top, insert SPDT switch (4) and solder off on bottom.
    7. On the top put a small dob of solder on SILVER1, SILVER2, SILVER3 and SILVER4.
    8. On the top, place AMS1117 regulator on solder dobs. Heat each leg briefly, to bond to solder. Add more solder as required.
    9. On the top, trace a black wire from BLACK1 to BLACK2, and solder.
    10. On the top, trace a black wire from BLACK3 to BLACK4, and solder.
    11. On the top, trace a red wire from RED1 to RED2, and solder.
    12. On the top, trace a red wire from RED3 to RED4, and solder.
    13. On the top, thread a -ve lead on a 10uF tantalum capacitor into YELLOW1 then onto BLACK3 on the bottom.
    14. On the top, thread the other +ve lead on the 10uF tantalum capacitor into YELLOW2 then into YELLOW3 on the bottom. This capacitor will have to lay flat so ensure enough play in the leads.
    15. On the bottom solder YELLOW1, BLACK3, YELLOW2, and YELLOW3. Bend the capacitor over behind the SPDT switch; make sure leads not touching other pads.
    16. On the top, thread a -ve lead on a 10uF tantalum capacitor into YELLOW6 then into YELLOW7 on the bottom.
    17. On the top, thread the other +ve lead on the 10uF tantalum capacitor into YELLOW8 then into YELLOW9 on the bottom. This capacitor will have to lay flat so ensure enough play in the leads. On the bottom solder YELLOW6, YELLOW7, YELLOW8, and YELLOW9. Bend the capacitor over towards the SPDT switch; make sure leads not touching other pads.
    18. On the top, insert a 100nF ceramic capacitor into YELLOW4 and YELLOW4, and solder.
    19. On the top, insert a 100nF ceramic capacitor into YELLOW10 and YELLOW11, and solder.
    20. To solder the Micro USB Breakout, the capacitors may need to temporarily be bent out of the way. On the bottom, insert the Micro USB Breakout into RED-V and BLACK-G, and solder 5 pins on top.
    21. On the bottom, glue 2P female header to ORANGE1 and ORANGE2. When dry, solder on top.
    22. On the bottom, glue 2P female header to ORANGE3 and ORANGE4. When dry, solder on top.
    23. On the bottom, glue 2P female header to ORANGE5 and ORANGE6. When dry, solder on top.
    24. Trim the solder/excess wire from the BRICK to be powered where the SPDT makes contact when joining the BRICKS.
    25. Add some insulation tape to the top of the SPDT.
    26. Bend the capacitors back.
    27. Join and solder the 2 BRICKS, ensuring the PCBs planes are parallel.

    Step 3: Testing

    As this is a generic power supply for the IOT123 BRICKS, you basically rerun the tests provided for the consuming BRICK. As we have used the 5PIN ATTINY85 NRF24L01 BRICK as an example consumer for this build, just rerun the test provided.

    Step 4: Next Steps

    As you can see the footprint of the IOT123 BRICKS is favourable against the D1M BLOCKS.

    These two can be used together: Several BRICKS collecting and sending data to a BLOCK, which then publishes to a MQTT server.

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