what is the purpose of a diode in a cordless drill or power screwdriver?
Interesting question. According to several answers posted here:
http://www.practicalmachinist.com/vb/general/how-size-diode-why-cordless-drill-142630/ ,
a "flyback" diode, or pair of back-to-back diodes, is used to suppress a high voltage spike when the motor is turned on or off.
This is very helpful
The purpose of a diode in a cordless drill or power screwdriver is to protect the tool's internal circuitry from damage caused by a reverse current flow. When a drill or screwdriver is operating, the motor generates an electromagnetic field that can create voltage spikes when it stops. These voltage spikes can potentially cause damage to other electronic components within the tool.
The diode is connected in parallel to the motor, and it allows current flow in only one direction. In other words, it acts as an electrical one-way valve, allowing current to flow from the motor to the battery or power source, but preventing current from flowing back from the battery to the motor. This ensures that any voltage spikes or reverse currents generated by the motor are safely dissipated through the diode instead of damaging the sensitive electronics of the tool.
To get a more detailed understanding of how this protection works, you can refer to the circuit diagram or the user manual of your specific cordless drill or power screwdriver. It will typically show the location of the diode and its connections within the internal circuitry.