Derative board using Synapse wireless modules

I'm planning a whole house automation system using Synapse wireless modules.  I figured I could whip up a board to do power/enerty monitoring also. I've studied the schematics & part list, but I have a few questions:

  1. Why can't the 9V AC be sent through a rectifier and regulator to provide 3.3V for the circuit? 
  2. What is the value of R3, R6, & R16? The schematic shows "15r". Is that supposed to be 15ohm? 

I think there might be a discrepancy between the current part list and the schematic. I count

  • 17 resistors in the board image
  • 16 resistors in the schematic
  • 12 resistors in the parts list

It would be nice for the part list to have a reference designator column also.

Great work, BTW. Thanks for sharing the info via opensource. I hope to use your energy monitor dashboard for my user interface of my data.





JMe87's picture

Re: Derative board using Synapse wireless modules

Hi, yzf600

1) the 2 sides of the 9VAC supply must be isolated from any part of the EmonTX. (except R13 and E14 of course). The simpliest and cheapiest way to make your 3V3 DC is to buy a small 9V 1A power adapter on eBay. 2,59 USD free shipping !

2) you are right : 15r equal 15 ohm

3) complete shematic and part list are available here :


Jacques (and you , did you have a name yzf600 ?)

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