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  • Brief description of the context (not really necessary to answer):

I built a quadcopter. The motors (small DC motors) and the electronics are powered by a single 3.7-4.2v battery. To prevent the microcontroller and the sensor to reset when there is a current spike in the motor's circuit, I put a 1000uF capacitor near the electronic part's supply and a schottky diode between the battery "+" and the capacitor, so that only the electronic circuit can use the capacitor's charge when needed. I also built a simple remote control which communicates with the quadcopter trough a couple of cheap 433mHz rf modules (on the receiver stands "xy-mk-5v"). At this very moment I can send all the needed settings to the quadcopter, calibrate it to remain as steady as possible and eventually tell him to fly: it takes off and flies for 3 seconds, then it automatically shuts down (as I wrote in the code for safety reasons). But during the flight there's a lot of noise in the circuit and the quadcopter can't receive any rf message (so I can't control it).


  • The question:

What I need now is a rf sistem which works with a noisy supply. I think I could:

a) filter the power supply;

b) change the rf modules (I payed something like 2 USD for the actual ones, but I could spend 20-30 $);

c) change the antennas (now I use a 172mm wires)

Would these things help? What else could I do? And how could I do these things (how could I build a good filter? What shape should the antennas have?)

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  • \$\begingroup\$ You should describe the noise so we can tell more \$\endgroup\$
    – PlasmaHH
    Jan 7, 2017 at 14:13
  • \$\begingroup\$ Just to understand your problem. Some questions: 1. Is your circuit on PCB. If so is there ground polygons, small ceramic filtering/coupling capacitors? 2. Do you use any coding scheme for rf communication? 3. Could you post any photo? \$\endgroup\$ Jan 7, 2017 at 14:28
  • \$\begingroup\$ Are you sure you can actually use 433 MHz? Depending on local regulations this may not be an appropriate choice. And should you go for another frequency (e.g. 2.4 GHz) your noise problems could disappear and/or require a different fix. \$\endgroup\$
    – user72833
    Jan 7, 2017 at 14:43
  • \$\begingroup\$ While sometimes difficult, attacking the noise source often provides a better result than attacking the noise's nasty effect on other modules. Start there first - perhaps you can use the RF comms to indicate success of your noise-suppressing efforts. \$\endgroup\$
    – glen_geek
    Jan 7, 2017 at 15:45
  • \$\begingroup\$ @tibo yes, I can. But since I'm probably buying new modules I could also change (2.4ghz ks allowed too). If I change what would the main differences be (regarding the noise problem)? \$\endgroup\$ Jan 7, 2017 at 16:15

1 Answer 1

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I'm not sure what range you are looking for, but for 433Mhz I have been successful using the antenna as described in the datasheet for the WL101 and WL102 modules.

26 turns of 3mm diameter with a 12mm tail for connecting to the module. For this I use an insulated 22 gauge wire and wrap it around the copper ground wire taken from household wiring. The result has been compact and worked for me.

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