A mini-drill machine is always needed in drilling the PCB (Printed Circuit Board).
It is usually powered by batteries that limit the drill’s capacity.
Using a power supply adapter with a speed regulator like the one featured here can certainly improve the performance of the drill.
With the help of this revolution regulator circuit you can control the number of revolutions of your drilling machine.
The speed regulator can maintain the speed of the drill no matter what load is encountered by the drill.
This projects measure the electromotive force (EMF) of a spinning drill motor to conclude the speed of the motor’s rotation.
Typically a motor takes power in the form of voltage and current and converts the energy into mechanical energy in the form of rotation.
With a generator, this process is simply reversed. A generator takes mechanical energy and converts it into both electrical energy with a voltage and current. Most motors can be generators by just spinning the motor and looking for a voltage/current on the motor windings.
The operation amplifier of IL723M monitor the voltage of generated EMF in real time.
I used Wheatstone bridge for comparing two different voltage: one voltage generated by EMF of motor and second:the serial resistance of resistors networks Ra + Rb.
The current sense resistors is R2. It’s measure the current through the drill machine.
The Wheatstone bridge is powered by very stable reference voltage inside integer circuit IL723M.
The complete instruction, schematic diagram et all
you can find in EMITER 3/2012,
follow the link: http://www.emiter.com.mk/poveke.php?napis_id=3971
Author: Primarius D-r Petar Avramovski, MD