Current Sources Information



Current sources provide reliable current levels for electrical component testing and for powering specialized components such as lasers. Current (or power) levels will remain constant during variation of load impedance.


Current sources are used in a wide variety of test applications such as relays, circuit breakers, satellite components, and power meters.How to Select Current Sources




Current source styles include PCB mount, printed circuit board or card mount, laboratory bench or portable configuration, rack mount, DIN rail mount, and freestanding or cabinet mount.



The most important specifications to consider when searching for current sources are the output specifications.  These include:


  • AC current - A source with AC current has at least one output providing alternating current.
  • DC current - A source with DC output has at least one output providing direct current.
  • Current phase - A single phase current has one alternating signal.  A three-phase current has three signals of current, typically 120° out of phase with each other.
  • Output current - The output current is the required full range of current output.
  • Output voltage - The output voltage is the maximum required voltage output.
  • Output power - The output power is the required rated power of the current source.


Output ControlHow to Select Current Sources


The output control of current sources is the output value that is monitored to provide a feedback loop to the current source so it can adjust the selected output in response to varying conditions such as load, line supply, temperature, etc. With a constant current output control current is held steady during load fluctuations. With a constant power output control power (VA) is held steady during load fluctuations. Constant optical power output control is for laser control; photodiode feedback controls output to maintain constant light. Current sources can have a single or multiple channels. 


User Interface

Options on current sources for user interfaces include:


  • Local interfaces - These can be analog or digital front panels.
  • Remote interfaces - Choices include analog signal monitors, analog signal controls, and computer interfaces.
  • Computer interface - Computer or network interface options include serial and parallel. 



Display types can be analog meters or indicators, digital readouts, or video display terminals. 




Common features include:


  • Output current monitors
  • Phase angle control
  • Pulse generators
  • Remote triggering
  • Voltage source

Some current sources come equipped with application software for control or for monitoring power supply performance.



Image Credits:


Block USA, Inc. | Dytran Instruments, Inc.