Using this electronic circuit, can be designed a DC motor control using LM317 voltage regulator and some classic electronic components. The c.c. motor control circuit of can be used in control circuits for minidrills.
The electronic circuit makes an internal resistance compensation: when the current through the motor increases, the supply voltage is automatically increased to offset the fall speed.
When this reaction occurs is set by potentiometer P1 and, therefore, circuit can be very well be adapted to any used motor. If you are using only small motors, power supply (transformer and rectifier bridge) can be changed(by transformer secondary current must be 1.5 times the maximum DC output).