The “Dimmer Not Dumber” fader saga has not closed. In the spirit of invention being the mother of invention, introducing “Dimmer Not Dumber IV“, for a customer who wants to control slide dimmers.
Here the “Dimmer Not Dumber IV” is going through its “homing” sequence. The stutter near the top allows the dimmer to travel beyond the proximity detection to reach maximum brightness. Once homed, the dimmers drop to the OFF “rest” state. The dimmers are programmed to move through a specific light sequence when triggered by the external control signals.
Dimmer Not Dumber IV: with pair of electrical light slide dimmers and control unit
Where the original “Dimmer Not Dumber II” design used servo-motor to control a residential rotary dimmer, the new design (and its failed predecessor, “Dimmer Not Dumber III“) uses a stepper motor to control a slide dimmer.
Talk about a hammer to crack a nut. This design uses a NEMA17 stepper coupled to a 1/4” 20 screw upon which a slide assembly that captures a corresponding nut rides. The end-stop, necessary to establish a “home” position for the steppers, uses an inductive proximity detector that is activated by the presence of a machine screw embedded in the slide assembly.
Dimmer No Dumber IV: showing fader base, motor mount, proximity mount, and slide assembly.
The pieces are cut from 12mmm and 6mm HDPE and connected using M3 machine screws. The whole assembly screws to the slide dimmer using the normal fascia mount.
Dimmer No Dumber IV: closeup of the 2-part slider assembly that captures the nut that rides on the screw. The countersink-head machine screw on the left triggers the inductive proximity detector at a distance of ~ 5mm.
The control software consists of an Arduino Nano and a pair of DRV8825 stepper motor drivers. The electronics, steppers and proximity detectors are powered through a 12v connection, and 24v control signals are conditioned to lower voltages for the Nano. Screw terminals are used to make the electrical connections for power, control signals (reset and trigger) and each detector. The entire electronics assembly is housed in a small enclosure created with from a 12mm HDPE base and 6mm HDPE top plate.