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Yes you should have a voltage divider because the signal is at battery level, which can be as high as 8V.The divider should drop it down to less than 3V if you are using a 3.3V arduino. I used a 5V arduino and the divider drops it down to around 4.8V.You will need a 1/2 or 1/3 divider. You could use a 10k resistor from gnd to the arduino pin and 20k or a bit lower from the arduino pin to the ppm signal. Then you have Uppm * 10/(10+20) = 1/3 Uppm on your pin.
If you have the tools to measure the actual voltage on your lines you could confirm if they are right.How is your wiring at the moment? You might have to use lower value resistors or maybe your signal level is too low.You can try it without the divider if the ppm voltage is not too high and you are using a 5v arduino. But i strongly recommend to reduce the voltage.If you are powering the arduino from the regulator i assume you use a 3.3v arduino so you will definetly need a ~1/3 divider. The resulting voltage is U_ppm * R2/(R1+R2)
The voltage divider is there because the arduino works at 5v logic level and the taranis at battery voltage, which can be up to 8V peak and that can damage the arduino.If you are using a 3.3V arduino it will damage it without a divider.You need to calculate the values depending on what resistors you have.A 1/2 or 1/3 divider should be okay. So you will have for example a 50k resistor from ppm to D2 and a 50k from D2 to gnd resulting in a 1/2 voltage divider.
The range is very limited. For me not more than the original remote. Maybe 30-50mDepends on your antenna and module.With some antenna modifications on the receiver side and with a real antenna on your transmitter it should be possible to get a way longer distance.
NRF24 jr module for toy quadcoptersView Instructable »