When you turn the speed knob from the 'off' position a small amount of current flows, this may make them less than ideal for N /009 or any lightweight motor which may start to creep forward without being commanded.
Model Railway Speed Controller 12v 2 amp PWM Module & NICE 27mm Knob. Fast Del.
HM Analogue Model Railway Speed Controller, Direction & Speed Control, Black
Lima Multi-Gauge Train Model Railway Speed/Direction Controller/Transformer #1
Vintage Kirdon Minor Model Railway Speed Controller Parts
Tri-Ang Model Railway Speed Power No 1Transformer Rectifier. 1 Working Order
Lima Multi-Gauge Train Model Railway Speed Controller Spares/Repairs
