user2967: I'm building a project that uses a couple of Adafruit DTH22 temp/humidity sensors. (https://www.adafruit.com/product/385)
I have them wired into my project box through 3.5mm mini plugs (The kind that are commonly used by stereo earbud headphones for MP3 players.)
More than half the time, when I plug/unplug one of my sensors, my Arduino restarts.
My guess is that as I plug in the plug, it sometimes momentarily shorts +5V and ground, causing the +5 source to my Arduino to lose voltage.
These sensors apparently draw single-digit mA of current at peak (like 1.5mA, according to the spec.) 
Could I wire a 120Ω or 150Ω resistor in line with the ground connection to the DHT22? This would limit the max current it could carry to around 40mA, which would not be a problem for my power supply (which is fed through the USB port on the Arduino, and thus is limited to 500mA.) Putting a resistor on the ground would limit the current to ground from either the VCC connection to the sensor or the data connection. It would also cause a small loss of voltage to both the data line and the VCC connection.
Would the serial connection between the DHT22 and my Arduino tolerate a 120Ω resistor, even if I connect it via ≈15M of 28-gauge wire?
I could also put the resistor into the VCC wire, but that would only current-limit a VCC-to-ground short, not data-to-ground.

user60518: Your case :
   Check wire (shors ?) and pin configuration (out ??)
General :
 No resistor in a ground path.
Decoupling supply :
  one can insert a 100 Ohms resistor between the arduino +5V and the +5V sensor : but ALWAYS use a decoupling capacitor : connect a 100µF betwen +5V sensor and groud. One can add a 100nF ceramic in paraller for digital devices.
Safety in case of bad I/O config :
  Using a 1kOhms restisor between Arduino and Device is good, if next to the Arduino (not at the other end of sensor cable, or use 330 Ohms at eatch end of cable).

2967: <p>I'm building a project that uses a couple of Adafruit DTH22 temp/humidity sensors. (<a href="https://www.adafruit.com/product/385" rel="nofollow noreferrer">https://www.adafruit.com/product/385</a>)</p>

<p>I have them wired into my project box through 3.5mm mini plugs (The kind that are commonly used by stereo earbud headphones for MP3 players.)</p>

<p>More than half the time, when I plug/unplug one of my sensors, my Arduino restarts.</p>

<p>My guess is that as I plug in the plug, it sometimes momentarily shorts +5V and ground, causing the +5 source to my Arduino to lose voltage.</p>

<p>These sensors apparently draw single-digit mA of current at peak (like 1.5mA, according to the spec.) </p>

<p>Could I wire a 120Ω or 150Ω resistor in line with the ground connection to the DHT22? This would limit the max current it could carry to around 40mA, which would not be a problem for my power supply (which is fed through the USB port on the Arduino, and thus is limited to 500mA.) Putting a resistor on the ground would limit the current to ground from either the VCC connection to the sensor or the data connection. It would also cause a small loss of voltage to both the data line and the VCC connection.</p>

<p>Would the serial connection between the DHT22 and my Arduino tolerate a 120Ω resistor, even if I connect it via ≈15M of 28-gauge wire?</p>

<p>I could also put the resistor into the VCC wire, but that would only current-limit a VCC-to-ground short, not data-to-ground.</p>
 60518: <p>Your case :
   Check wire (shors ?) and pin configuration (out ??)</p>

<p>General :
 No resistor in a ground path.</p>

<p>Decoupling supply :
  one can insert a 100 Ohms resistor between the arduino +5V and the +5V sensor : but ALWAYS use a decoupling capacitor : connect a 100µF betwen +5V sensor and groud. One can add a 100nF ceramic in paraller for digital devices.</p>

<p>Safety in case of bad I/O config :
  Using a 1kOhms restisor between Arduino and Device is good, if next to the Arduino (not at the other end of sensor cable, or use 330 Ohms at eatch end of cable).</p>
