The simpler galvanostat consists of a high-voltage source producing a constant voltage with a resistor connected in series: in order to force an almost constant current through a load, this resistor shall be much higher than the load resistor . As a matter of fact, the current through the load is given by
and if >>, the current is approximately determined by as follows
This simple realization requires rather high voltages (~100 V) to keep the load current constant with sufficient approximation for all practical purposes. Therefore, more complex versions of galvanostats, using electronic amplifiers with feedback and lower voltages, have been developed and produced. These instruments are capable to feed constant currents in the ranges from few picoamperes (pA) to several amperes (A); typical construction for use in the lower range of feed currents uses operational amplifiers.
Galvanostatic deposition techniques can be used for some thin film deposition applications where there is no need to control morphology of the thin film.[citation needed]