I have an Arduino Nano that I'm powering through 3 X 1.5V batteries. Measuring "vin" - "gnd" pins gives me 4.3V but measuring "3.3V" - "gnd" pins only gives me 2.8V I'd have expected to see 3.3V there. Any ideas as to what's going on?
The Nano is a Chinese clone and I have a nrf240l radio attached to it.
Thanks Grumpy_Mike for your response but not sure if I understand; isn't the 5V pin an output? My nrf240l does need to be connected to 3.3V, so are you suggesting that if I connect my 4.5V battery to the 5V pin, I can draw 3.3V on the 3.3V pin?
The 5V pin is an output, but many of us use it as a way to power our projects (in fact, I’m working on a new project that powers an Arduino through the 5V pin). If you do so, you will still be able to draw power from the 5V. I’m not sure about the 3.3V pin, but I’d think it’d work
I know this isn’t my thread, but I had a question that retains to this. Let’s say I’m using an Uno (or any board that has a 5V pin and a 3.3V pin) and I power it with a stable 5V. Will the 3.3V pin give me 3.3V or will it just no work or give me 5V?
Not really. It is more correctly a "reference" pin for 5 V devices, but principally it is the proper way of powering the Arduino since it is a direct connection to the 5 V line for the ATmega chip and the USB interface.
Of course, when you use the USB interface you feed - again , 5 V - into the USB connector and you can get something approaching 5 V from the "5V" pin except that there is a diode in between, dropping some fraction of a Volt and with (generally) a 500 mA current limitation. And if you are not connecting via USB, the USB chip is wasting your battery power; it would be better to use a Pro Mini.
"Vin" should be strictly avoided.
Finally, a Chinese clone may or may not actually have a 3.3 V regulator capable of powering a NRF device.
If you are powering it via 5 V, you have a 3.3 V regulator regulating down from the 5 V line. Except for clones deriving 3.3 V from the USB chip which have a very limited current capability.