I’m building a low power node with a Pro Mini 3.3V, to measure distance (HC-SR04) and sent it via lora (RFM95 module).
It consists of a mosfet that is switched on and off, regulator, level converter and the US sensor.
It worked perfectly fine on my breadboard but after soldering it to a prototype board, it doesn’t work anymore.
Does anyone see a problem in the schematic? (Sorry for the drawing, I’m a bit limited here, I hope it is clear).
Mosfet (I know, overkill): https://de.aliexpress.com/item/10PCS-IRLB8721-TO220-IRLB8721PBF-TO-220-free-shipping/32714364118.html?spm=a2g0s.9042311.0.0.FjZdIJ
Lvl Converter: https://de.aliexpress.com/item/Free-shipping-1pcs-4-channel-IIC-I2C-Logic-Level-Converter-Bi-Directional-Module-5V-to-3/32670479389.html?spm=a2g0s.9042311.0.0.OAwsE9
I have verified all the connections.
Right now it seems to reset all the time (2nd LED blinking on the arduino).
The regulator switches on and off with 1hz, the voltage between I+ and I- changes between 1.0V and 2.4V
If I connect GND to the regulator directly, bridging the Mosfet, it works fine.