Can emonTx v3 work without ac-ac adapter only with voltage taken from usb -> uart cable? Because I configured Arduino IDE and when I'm changing the power source attached to my CT sensors the date on the serial monitor is not changing at all. For channels 1-3 this value on the serial monitor is always about 30 and for channel 4 the it's about 8. Maybe I need to change a firmware of my emonTx?
What values can I measure using dc adapter? (I don't have ac-ac adapter)
Submitted by alexlember on Wed, 21/01/2015 - 19:15»
Re: What values can I measure using dc adapter? (I don't have ac-ac adapter)
"Can emonTx v3 work without ac-ac adapter only with voltage taken from usb -> uart cable" Yes. You can measure current and you can estimate apparent power. The numbers you are seeing, assuming you are using the default sketch, is the apparent power in VA, given that the system voltage is 230 V, and if no current is flowing, that "30" is noise from the digital circuits inside the processor. Also, your CT must be on a single-core cable. If it is on a two-core or three-core cable, it will not work.
Re: What values can I measure using dc adapter? (I don't have ac-ac adapter)
Thanks for your answer, Robert!
As I understood, it doesn't matter whether to use ac or dc adapter if I want to measure apparent power, but I have 220 voltage at my house, do I need to change emonTx firmware a little thought?
Re: What values can I measure using dc adapter? (I don't have ac-ac adapter)
Ideally, you do (you have a programmer?) because you will be reading about 4½% high. If you are using only emoncms to see the data, you could scale it in there instead.