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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 disappears when I touch the module's body with my hand.

Kindly, I need to know:

  • What is the problem ?
  • What does my hand do?
  • How can I simulate my hand touching the module so that I can keep my hand away?

If you need more details just ask, I will be more than happy to answer.

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Because the noise is attenuated when you touch the module, it is likely that the problem is noise from your power supply getting into the module. When you touch the module, you effectively grounding it, which attenuates the power supply noise.

It is likely that your power supply is not grounded. If possible, get a grounded power supply. Such a supply, if it comes from the AC mains, will have three prongs, instead of two.

If you are powering your device from the USB port of a laptop, you might try, as an experiment, running the laptop off of battery, instead of the external power brick. See if that causes the noise to attenuate.

Does your module have a pin labeled "GND" or something similar?

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  • \$\begingroup\$ This is the power source i am using adapter . yes it is just two prongs but here we don't have three prongs at all. and yes of course the module has GND pin this is the module i am using sim800l. can i simulate the finger touch by connecting gnd with the module's body for example? \$\endgroup\$
    – Mohamed Essam
    Commented Feb 4 at 1:58
  • \$\begingroup\$ That looks like a US plug. Do you live in the US or in a country that has grounded recepticles? \$\endgroup\$
    – Math Keeps Me Busy
    Commented Feb 4 at 2:04
  • \$\begingroup\$ No i live in egypt, and actually not everyone here has grounded receptacles \$\endgroup\$
    – Mohamed Essam
    Commented Feb 4 at 2:18
  • \$\begingroup\$ Someone else may have a better idea. When I was young I had a phonograph amplifier with the same problem you are experiencing, and I attached a wire from a water pipe to the amplifier to ground it. It was a hack, and really don't know what else to say. You might try buying a more expensive "linear" power supply with a transformer, but that may not be in your budget, and it may not fix the problem either, if you don't have a ground. If you do have a plug with a ground, you could try ground with amazon.com/StaticTek-Adapter-Universal-Connection-Unbreakable/… \$\endgroup\$
    – Math Keeps Me Busy
    Commented Feb 4 at 3:01
  • \$\begingroup\$ I'll try another PSU with a transformer as you mentioned. Anyway thank you, i really appreciate your effort. \$\endgroup\$
    – Mohamed Essam
    Commented Feb 4 at 3:10

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