Wemos d1 mini relay

Hi, I read somewhere that the relay board for the wemos d1 mini powers the wemos board so that you don’t need a 5v power supply plugged in? Can this be done with your app?

I don’t undersand very well your question: but I’ve now on my hands a WeMos D1 mini with a relay board, so… I can command the relay (on D1 input) directly from a Blynk project.
The WeMos is powered just with an USB 2.0.

Me neither.

@shenery I’m not really a user of relays but my understanding is that the WeMos can only give power to the relay board / shield and not the other way around. So you need 5V from somewhere. As @naamah75 points out Blynk can for sure control the relay.

I mean I though you didn’t have to power the wemos with USB I though the wemos took a power to the relay and converted it to 5v to power it. The relay has a 5v and g pin on it.

You don’t have to use the USB to power the WeMos and you can provide power to the 3V3 or 5V pins. Where is the power going to come from? A battery pack or perhaps a mains outlet stepped down to 3.3 or 5V.

You seem to be indicating the devices produce their own power from thin air. Shield and WeMos without power can’t generate power. Perhaps I am missing your point.

Power goes in the relay shield and with the shield soldered to the wemos board I thought would power it though the 5v pin?

I have set up a simple button with the plug side of the wire going to common and the lamp side going to the normally open.
Problem is, is that I have to power the board via USB to enable it to work instead of the relay doing all the work from the plug.
Does that make sense?

@shenery the schematic is here https://www.wemos.cc/sites/default/files/2016-09/relay_new.pdf and the relays themselves are at https://www.wemos.cc/product/relay-shield.html

Power doesn’t have to come from the USB but it has to come from somewhere and that is not the relay circuit. You might be better off asking on the WeMos forum and then when you have found some power return here if you need any assistance controlling the relay over the internet.