I have a problem understand wire inductance. I know that the longer a wire gets the more inductance it has. Also, the longer a wire gets the more capacitance it will have.
Now, I have a 20 meter long sensor and it is power by a drive signal (+/- 1.5V and sometimes +/- 3V). Now I found out that when I use a much longer sensor that the current draw increases a little. I was trying to figure why this is the case. Does anyone have any idea? EDIT: I must add that this drive signal is made by an opamp circuit that is power by the power supplies of +/- 4.2V. That is where I calculate my power. The +/- 1.5V and 3V stays virtually on changed.
The main part of the sensor is a wrapped coil and it is connected inside the sensor to the 20 meter long cable of which is connect to the actual electronics (the electronics power the sensor). The coil is a core wrapped with wire and has its two ends attached to the 20 meter cable in series (wires 2 ends). I used an LCR meter to see the series inductance of the sensor. Then I added 30 more meters to the sensor and the LCR meter showed the series inductance become less. Is that suppose to happen? Should it not go up by added more wire? But if it is actually going down that should explain why more current is drawn (smaller inductance lets in more current right?) or am I just stupid?
I have really no idea how to justify why this longer cable draws more current than the shorter cable. It is probably something real simple that is going over my head. If you could help me I appreciate it.
Dru
Now, I have a 20 meter long sensor and it is power by a drive signal (+/- 1.5V and sometimes +/- 3V). Now I found out that when I use a much longer sensor that the current draw increases a little. I was trying to figure why this is the case. Does anyone have any idea? EDIT: I must add that this drive signal is made by an opamp circuit that is power by the power supplies of +/- 4.2V. That is where I calculate my power. The +/- 1.5V and 3V stays virtually on changed.
The main part of the sensor is a wrapped coil and it is connected inside the sensor to the 20 meter long cable of which is connect to the actual electronics (the electronics power the sensor). The coil is a core wrapped with wire and has its two ends attached to the 20 meter cable in series (wires 2 ends). I used an LCR meter to see the series inductance of the sensor. Then I added 30 more meters to the sensor and the LCR meter showed the series inductance become less. Is that suppose to happen? Should it not go up by added more wire? But if it is actually going down that should explain why more current is drawn (smaller inductance lets in more current right?) or am I just stupid?
I have really no idea how to justify why this longer cable draws more current than the shorter cable. It is probably something real simple that is going over my head. If you could help me I appreciate it.
Dru