Driving 4 100mA motors using GPIO pins and BS170s
If you have a little bit of leeway in what voltage the motors can take then one option is to use a ULN2803A to drive the motors directly. The device comes in a SOIC-18 package, and even includes flyback diodes in order to save as much board space as possible. Tying the drivers together in pairs will distribute the load across each, keeping the voltage drop low.







simulate this circuit &ndash; Schematic created using CircuitLab