I've been doing a lot of breadboarding lately. I have a breadboard power supply that is supposed to provide 3.3 and/or 5v. But normally, I let the USB provide the nodeMCU with power. Over the course of the last 2 weeks I have found 2 nodeMCUs to be inoperable. Most recent one was today. I was preparing to test in a location not near to my PC so I was going to provide the node with 3.3v from the power supply. Can't flash or anything. Never could figure out why. Just figured it out. When it happened today, the node was hot. That led me to think power. I metered both legs and found out the jumpers have no effect. Regardless of the jumper setting on the power supply, it always outputs 5v on both legs. I rejiggered the breadboard by adding a 3.3v regulator (LD33V) and providing the nodeMCU board with 3.3v. Metered it and all looked good. Running fine now with a new nodeMCU.
Lesson learned. First avoid breadboard power supplies. Second, if you do use one, meter that sucker first to make sure you are getting what you want. Third, build yourself your own 3.3v/5v power supply using a LD33V and a M7805C.
Now, two nodeMCUs to the trash. Power supply will be next. What a pisser.
Another unrelated learning. When you buy nodeMCUs, they are not all the same. The most recent ones I bought have a different footprint than the previous ones. The pins are farther apart by two rows. As a result,they don't work on a breadboard cause there is no place to put a jumper to access specific pins. This has also motivated me to put three headers on my prototype boards with one side spaced 2 rows wider. This will allow me to interchange node chips if I need to. More soldering but other than that I think it should work.
Lesson learned. First avoid breadboard power supplies. Second, if you do use one, meter that sucker first to make sure you are getting what you want. Third, build yourself your own 3.3v/5v power supply using a LD33V and a M7805C.
Now, two nodeMCUs to the trash. Power supply will be next. What a pisser.
Another unrelated learning. When you buy nodeMCUs, they are not all the same. The most recent ones I bought have a different footprint than the previous ones. The pins are farther apart by two rows. As a result,they don't work on a breadboard cause there is no place to put a jumper to access specific pins. This has also motivated me to put three headers on my prototype boards with one side spaced 2 rows wider. This will allow me to interchange node chips if I need to. More soldering but other than that I think it should work.