Speed controller using pulse-width modulation (NE555) for up to 20W DC motors. Operates on 12V DC supply. PCB 45 x 33 mm.

• Control power can be increased by replacing transistor TR1 with, for example, switching FETs IRF540, IRFZ44 etc.
• Workshop tip: if it squeals annoyingly, replace the outermost 10nF ceramic capacitor with, say, a 1nF value