Constant Current Drivers
The Biophysica Constant Current Driver modules are adjustable, high quality precision power supplies for driving a category of devices which function more by current than by voltage.  We can supply a range of modules from 1 milliampere to 5 amps driven by voltages from 1.5 v to 60 v.  We use state-of-the-art digital high frequency switching control circuits which run cool and are very compact.  We soon expect to be able to control DC  or pulsed currents up to 20 amps at 100 volts. These modules are instantly adjustable and programmable by the user or can be fixed at some current level of your choice. As with any high quality CC supply, they can withstand a permanent short-circuit of the output terminals without blowing a fuse.

Definition:  A Constant Current Source will maintain the chosen current notwithstanding changes in load resistance or in voltage supply.  A Constant Current Source must still follow Ohm's Law which defines the relationship between Voltage, Current and Resistance V=IR or I=VC (where C= Conductivity).  Constant Current is maintained by a negative feedback control loop which measures actual current flowing in the load and uses that signal, after suitable inversion and amplification, to instantly adjust for any changes in conductivity or voltage.

Limitations:   Ohm's law dictates that a power supply cannot deliver more current than the product of Voltage and Conductivity in the circuit. In other words, if the voltage source is not high enough or if the circuit is not conductive enough, current will not be able to reach the chosen final value. This situation often occurs in water ionization where the water is too pure and insufficiently conductive.  The remedy is to add salts to make the water more conductive or to raise the supply voltage to 50 or 100 volts.

Application are in:

  • Water ionization, electrolysis and iontophoresis where ion flux depends on current flow.
  • Etching and plating industries where current must remain constant regardless of conductivity of the electrolyte solution.
  • Groups of series-connected light emitting diodes or incandescent lamps for the lighting industry, where addition or removal of lamps will not change the current through the series.
  • Groups of series-connected heating elements. Heat is proportional to current, not voltage.
  • Driving inductive loads such as solenoids, coils, transformers.
  • Battery driven devices where battery voltage may fluctuate wildly or may slowly diminish over time.
  • Capacitor charging with a highly linear charging rate.
  • Battery charging.
  • Driving DC motors at constant speed.

We also supply miniature precision switching voltage supply modules from 1 volt to 100 volts DC.

This page last updated April 18, 2006

E-mail: info@biophysica.com

or phone (905) 827-9448

Back to Home Page