Hi Alex, because the FloJack/ACR35 uses a non-standardized data interface across the audio port it is subject to some limitations. Not all Android devices are capable of demodulating the data. A list of supported Android devices are listed here. In the event that the host Android device you are using is listed, then the instability issue could be because the headphone volume on the host device is low, the battery on the FloJack/ACR35 is low, or their has been some damage to the audio path on either device. It may be best to first test out the FloJack with an iOS device before trying to get it working with your Android device. This will help narrow in on the problem.
With that said, I will point out that the Android platform is not our focus for the FloJack/ACR35 device. We recommend the FloBLE for Android integration as the data interface is over Bluetooth and much more standardized than the Audio jack. Therefore the data being captured by the reader scanning NFC cards is more predictably sent to the host Android device independent of the make of the device. We have FloBLE units in stock and are recommending customers that are having issue with the FloJack shift over to it.
thanks,
Richard
