Power for Simultaneous RFID Tag Reader (SRTR)

Sensors NFC & RFID
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  1. If I am using Target Power from a RedBoard on the 5v pin, would I need to open JP1?

  2. In the SRTR docs, it states to use 5V (rather than 9V) input on the barrel connector of the RedBoard so that the voltage regulator does not get red-hot. That makes sense. However, the RedBoard clearly states the barrel connector should receive between 7 and 15 volts. The board does power up on clean 5V. I am just not sure if there are any repercussions with doing that. I suppose getting a 7v would be a compromise, but that is not a common part i have laying around :slight_smile:

  3. I might have missed it. What is the max draw in amps this SRTS might pull at full power? I am using a 5V5A regulator to power the RedBoard. I am hoping I have enough power left over to power some other devices :slight_smile:

  4. Would a heat sink sit on topside of the board? I am thinking no since there is a sticker on that chip and it that would not be good for conduction of heat. I suppose the design is for a sink to be attached to the large metal plate on the bottom of the shield. Just checking. That doesn’t really make sense if used as a hat. The docs are not clear to me how to attach. I found an example of someone else using this board and they attached a sink on the top.

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I saw reference to 4. in the forum and it looks like the heat-sink is meant to be on the bottom.

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  1. If I am using Target Power from a RedBoard on the 5v pin, would I need to open JP1?
No, JP1 isolates the serial header from the power bus on the SRTR. It's only there you're externally powering the board and want to prevent your external power from backfeeding down through the serial connector.
  1. In the SRTR docs, it states to use 5V (rather than 9V) input on the barrel connector of the RedBoard so that the voltage regulator does not get red-hot. That makes sense. However, the RedBoard clearly states the barrel connector should receive between 7 and 15 volts.

5 volts will slightly under power the RedBoard, but the RedBoard will be fine with that. The 5 volt regulator on the RedBoard is maxed out by the SRTR and under powering the RedBoard is done to prevent overheating the regulator.

  1. I might have missed it. What is the max draw in amps this SRTS might pull at full power? I am using a 5V5A regulator to power the RedBoard. I am hoping I have enough power left over to power some other devices :slight_smile:

We’ve actually have never measured this as far as I know. The data sheet says to expect up to 1A of current draw from the module and the Arduino won’t draw too much, probably less than 200mA.

  1. Would a heat sink sit on topside of the board?

The Thing Magic module has a metal RFI shield on top and the heat producing components are not thermally bonded to it. It would provide some cooling but wouldn’t be very effective. The bottom of the board is where the heat’s at. That’s where you would want a heatsink.