25-02-2017, 08:28
I gave a look to your the real time graphs, and it seems those abnormal "night readings" during last night, suddenly stopped at 3:32, and up to near the sunrise they haven't appeared again.
The circuit design used in the AMS1117 series requires the use of an output capacitor as part of the device frequency compensation. The addition of a 10 to 22 uF solid tantalum capacitor on the output will ensure stability for all operating conditions.
...
To further improve stability and transient response of these devices larger values of output capacitor can be used.
C7 is supposed to do this job on the 5V voltage regulator. Following the datasheet it should be tantalum, however I also already have used electrolytic caps in the output of AMS1117 regulators.
Quote:I can confirm I have a 10uF/16V Tantalum capacitor in C7 in the Transmitter board 3.12. This made me question what I had in my original Transmitter board, 3.11 and guess what I spotted that I had used: Electrolytic capacitors in C7 and C8. Maybe by using the correct type or capacitor, it has simply made the system more sensitive if these capacitors have an effect on this part of the circuit?
The circuit design used in the AMS1117 series requires the use of an output capacitor as part of the device frequency compensation. The addition of a 10 to 22 uF solid tantalum capacitor on the output will ensure stability for all operating conditions.
...
To further improve stability and transient response of these devices larger values of output capacitor can be used.
C7 is supposed to do this job on the 5V voltage regulator. Following the datasheet it should be tantalum, however I also already have used electrolytic caps in the output of AMS1117 regulators.