Temporarily powering 5.5v board from 2.5v ethernet cable

[kzgrey]

I'm not an EE. I'm a Software Engineer.

I would like to build a small circuit that would leach power from an active 2.5v Ethernet line to charge a capacitor very slowly (over a timespan of 1-2 minutes). When the capacitor is fully charged, it would then discharge at 5.5v to power a circuit containing an Atmel chip and an I2C sensor.

Q1) Is this possible?
Q2) Would charging the capacitor block traffic over the Ethernet cable?
Q3) Can anyone give me a rough idea what this circuit should look like and what the specs of the capacitor should be?

Alternatively, can someone refer me to an EE who could design this for me?

 

[skeptic2]

http://en.wikipedia.org/wiki/Voltage_multiplier

 

[NascentOxygen]

I would like to build a small circuit that would leach power from an active 2.5v Ethernet line to charge a capacitor very slowly (over a timespan of 1-2 minutes). When the capacitor is fully charged, it would then discharge at 5.5v to power a circuit containing an Atmel chip and an I2C sensor.

Q1) Is this possible?

Probably, providing your circuit doesn't draw much current. (To supply 10mA at 5.5V may equate to taking, say, 30mA from the Ethernet.)

It's not clear for how long you wish to power your circuit, but I assume its for some minutes, at least?

Q2) Would charging the capacitor block traffic over the Ethernet cable?

It would, but this could probably be prevented by incorporating a filter to block that data signal. An RF choke built around a ferrite core should do the job, allowing the DC through but isolating your circuit from the digital data on the line.

Beyond this general discussion, I can't help much though.

 

[CWatters]

Have you looked at the PoE standard?

http://en.wikipedia.org/wiki/Power_over_Ethernet

There are commercial plug and play adaptors designed to inject and extract the power from standard Ethernet cable. You can also build the circuit into your device if you don't want a physically separate unit.

 

[alphy]

I cannot provide a definitive answer without more information about the specific components and design of the circuit. However, in general, it is possible to temporarily power a 5.5v board from a 2.5v Ethernet cable by using a capacitor to store and regulate the voltage.

Q1) Yes, it is possible to use a capacitor to slowly charge and then discharge at a higher voltage to power a circuit.

Q2) Charging the capacitor should not block traffic over the Ethernet cable as long as the circuit is designed properly and does not interfere with the data transmission.

Q3) The design of the circuit and the specifications of the capacitor will depend on the specific components and requirements of the project. It is recommended to consult with an experienced EE for assistance in designing and building the circuit.

Alternatively, you can also research and learn more about power regulation and capacitor selection to design the circuit yourself. There are many online resources and tutorials available that can guide you in the process.

I hope this information helps and good luck with your project!