I am working on a project with "SIM800L" GSM module, the problem is that there is a noise from the module in the calls and it dissappears when i touch the module's body with my hand.
kindly i need to know
If you need more details just ask, i will be more than happy to answer
your answer is much appreciated Thanks in advance.
That sounds like a grounding problem. A schematic showing how this is wired and links to the other hardware. A clear photo would also help.
You are using a buck converter for your 4V DC and giving it a 5V input. I am fairly sure that is the source of your problem, it needs a few more volts to work properly. The solution would be to power it from the 12V DC. Be sure grounds are passed through on both converters. If so simply connect the 4V converter's input to the 12V. The grounds must be connected for everything. If the grounds do not pass through you will need a different converters(s). The converters I have that look like that have the grounds passing through. Under voltaging the 4V converter will place a lot of EMI (ElectroMagnetic interference) on the 4V bus.
But i don't think it is because of the buck converters, because i was using a bench PSU while testing the circuit and it was pretty same problem.
I am just curious of how to simulate the hand touching the module.
I have a new wierd update. I wrapped the SIM800L in aluminum foil, and the result was that there was a loud noise “on the first call only after connecting the device to electricity for the first time,” and then after that this noise disappeared completely in all other calls.
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