Skip to main content
Electrical Engineering

Return to Question

added 50 characters in body
Source Link
A__
A__
  • 111
  • 4

I am new to electrical engineering.

I cut the barrel jack off the end of a 24V DC power adapter, exposing a red and white wire. I'm trying to determine the polarity of the red and white wires with a multimeter. Here's what I've tried, with my multimeter ends connected like so: black to COM, red to V/mA/uA/omega/Hz/Temp.

  1. Set multimeter to VDC mode (as opposed to VAC)
  2. Touch Black tip to white wire, red tip to red wire.
  3. No reading at any range (including mV)
  1. Set multimeter to VDC mode
  2. Touch black tip to white or red wire
  3. Touch red tip to wall jack side of the adapter
  4. No reading
  1. Set multimeter to VAC mode
  2. Touch black tip to white or red wire
  3. Touch red tip to the other wire
  4. Steady reading of some random low voltage

Why aren't I getting a voltage reading from my power adapter? It worksThe multimeter gives accurate voltage readings when tested with a battery. Note that I haven't plugged the adapter into a power source as I read this is dangerous, so I don't quite understand how I'm supposed to get a reading?

I am new to electrical engineering.

I cut the barrel jack off the end of a 24V DC power adapter, exposing a red and white wire. I'm trying to determine the polarity of the red and white wires with a multimeter. Here's what I've tried, with my multimeter ends connected like so: black to COM, red to V/mA/uA/omega/Hz/Temp.

  1. Set multimeter to VDC mode (as opposed to VAC)
  2. Touch Black tip to white wire, red tip to red wire.
  3. No reading at any range (including mV)
  1. Set multimeter to VDC mode
  2. Touch black tip to white or red wire
  3. Touch red tip to wall jack side of the adapter
  4. No reading
  1. Set multimeter to VAC mode
  2. Touch black tip to white or red wire
  3. Touch red tip to the other wire
  4. Steady reading of some random low voltage

Why aren't I getting a voltage reading from my power adapter? It works with a battery. Note that I haven't plugged the adapter into a power source as I read this is dangerous, so I don't quite understand how I'm supposed to get a reading?

I am new to electrical engineering.

I cut the barrel jack off the end of a 24V DC power adapter, exposing a red and white wire. I'm trying to determine the polarity of the red and white wires with a multimeter. Here's what I've tried, with my multimeter ends connected like so: black to COM, red to V/mA/uA/omega/Hz/Temp.

  1. Set multimeter to VDC mode (as opposed to VAC)
  2. Touch Black tip to white wire, red tip to red wire.
  3. No reading at any range (including mV)
  1. Set multimeter to VDC mode
  2. Touch black tip to white or red wire
  3. Touch red tip to wall jack side of the adapter
  4. No reading
  1. Set multimeter to VAC mode
  2. Touch black tip to white or red wire
  3. Touch red tip to the other wire
  4. Steady reading of some random low voltage

Why aren't I getting a voltage reading from my power adapter? The multimeter gives accurate voltage readings when tested with a battery. Note that I haven't plugged the adapter into a power source as I read this is dangerous, so I don't quite understand how I'm supposed to get a reading?

Source Link
A__
A__
  • 111
  • 4

Why aren't I getting a voltage reading from my AC/DC power adapter

I am new to electrical engineering.

I cut the barrel jack off the end of a 24V DC power adapter, exposing a red and white wire. I'm trying to determine the polarity of the red and white wires with a multimeter. Here's what I've tried, with my multimeter ends connected like so: black to COM, red to V/mA/uA/omega/Hz/Temp.

  1. Set multimeter to VDC mode (as opposed to VAC)
  2. Touch Black tip to white wire, red tip to red wire.
  3. No reading at any range (including mV)
  1. Set multimeter to VDC mode
  2. Touch black tip to white or red wire
  3. Touch red tip to wall jack side of the adapter
  4. No reading
  1. Set multimeter to VAC mode
  2. Touch black tip to white or red wire
  3. Touch red tip to the other wire
  4. Steady reading of some random low voltage

Why aren't I getting a voltage reading from my power adapter? It works with a battery. Note that I haven't plugged the adapter into a power source as I read this is dangerous, so I don't quite understand how I'm supposed to get a reading?