Hello, I'm in the US and I've purchased a prebuilt EmonTX along with other items I'll need to monitor a Solar PV system (I hope ;-). I purchased a 9V AC-AC power supply here and it failed to power the EmonTX. After testing I found that the power supply wasn't working at all. I exchanged the unit today for a working one and then I tested it prior to connecting it and it worked fine. When I connect the adapter (that came with the EmonTX as my 2.1mm plug will not plug directly into it) I'm not getting any readings from it. I quickly disconnected it in case that was what caused the failure of my first power supply. Am I missing something here or is it possible that the adapter that shipped with the EmonTX is no good?
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Re: 9V AC-AC Adapter Problem
What is your mains voltage there, and what is the input voltage of your adapter? If you have the Ideal Power DB-06-09, that is for 230 V input, it works down to 210 V at 50 Hz so it should be OK for 230 V, 60 Hz but it will not work on 115 - 120 V. The current drawn by the emonTx is quite small (in comparison with the output of the adapter) so it is unlikely that it was the emonTx that killed the adapter.
What are the "other items" that you have? Do you have a programmer, or a 5 V USB power supply, that you can power the emonTx with?
Re: 9V AC-AC Adapter Problem
The mains voltage is 240 coming into the home (2 legs of 120) and the adapter input is 120V at 60Hz (output is 9V 1A). I didn’t purchase an adapter from the site as I’ve got somebody (who’s much more savvy with electric than I) who’s going to help me with the calibration here and I didn’t want to deal with a plug outlet adapter (figure that would throw off all the measurements listed on the site anyway). I bought an SR Components 9V AC-AC adapter here (http://www.srcomponents.com/power-supply/ac-to-ac/ac-to-ac-9v-1a-2-1mm-f...)
I do have a programmer and a 5V usb power supply. I’m currently powering the device with batteries and it’s working fine with the base (pi) but I haven’t yet connected it down at the mains. It just seems odd to me that I’m getting the correct readout from the end of the 9V adapter but then, when I connect the plug (which shipped with the EmonTX) and test it before plugging it into the EmonTX, I’m getting nothing.
Re: 9V AC-AC Adapter Problem
I think it's a simple case of a faulty 2.1 mm to 2.5 mm adapter - have you checked it for continuity with an ohmmeter? Incredible as it might seem, I have seen similar units with no connection from one end to the other. I think you need to get your "somebody" to check it for you.
Don't be surprised if you get more than 9 V from your ac-ac adapter - we expect around 11 V and the circuit is designed for that. Because it isn't the one we specify, you might need to adjust the calibration values in the sketch to give the correct voltage reading.
Re: 9V AC-AC Adapter Problem
Thank you. That's what I was hoping and I'll pick up another adapter Thursday and test.