A simple circuit comprising of a 555 timer and a power mosfet to control the speed of a mini PCB drill.
One of the tools my workshop needed was a pcb drill speed controller, since I have lost my original controller that came with the drill. The circuit wouldn’t need to be over complicated since a simple 555 timer and a power mosfet to drive it at 18v would be enough to send a PWM signal to the drill to control its speed.
This controller circuit generates a PWM signal to control the drill speed, it uses a 555 timer in astable configuration. The duty cycle, or on/off time, can be modified by adjusting the 100k ohm potentiometer connected through screw terminals (X2), thus changing the drills speed. The mini drill requires an 18v supply and this is driven though Q2 IRF540 mosfet to separate the load voltage from the 5v supply voltage that is used for the rest of the circuit.
|Qty||Part Id||Part Description||Value|
|1||R1||1/4w Metal Film Resistor||1K|
|1||R2||1/4w Metal Film Resistor||470R|
|1||R3||1/4w Metal Film Resistor||500R|
|1||C1||Metalized polyester capacitor||100n|
|1||C2||Metalized polyester capacitor||10n|
|1||IC2||555 Timer IC||NE555|
|1||Q2||N Channel Power Mosfet||IRF540|
|1||X1||4 Way Screw Terminal|
|1||X2||3 Way Screw Terminal|