- 2 5mm LEDs You'll note several of these lines? (would these 4 lines **ever** connect to the PSU? -Consider: 1 simple on/off switch/button/knob/etc. - 2 5mm LEDs - one per step // 1 for once/cont (sw15 // 2 NO Moment switches: // 1 for once/cont (sw15 // 2 NO Moment switches: // 10 steps (sw1-sw10 // 1 for once/cont (sw15 // 2 NO Moment switches: // 1 rotary switch - 9.5mm, +5mm extra space available - mini toggle switch - 9.5mm.