Received the IotaWatt device today and it is up and running. As I’m in the UK and had a number of PSUs lying around I ordered without one. I notice the one that is sold for Euro plugs is rated at 0.2 Amps. How little can I get away with? I’ve got a Nest thermostat PSU rated at 0.1 Amps. Would that be enough?
The Euro PSU sold in the stuff shop is a CUI SWI3 series supply. The nameplate says .2A input at 90 ~ 264 VAC.
The 3 in SW3 indicates 3W. The output is 5 VDC so the current is rated at 600mA.
Have not tried to determine the minimum requirement. What happens when current is restricted is subtle. The bias voltages to the CTs starts to sag, which does not produce any obvious indication. Safe to stay with a 600mA or better supply.