The automatic finger shown in the video is the result of a self-imposed challenge to make a device to drive my Wooden Finger Engine with no modifications to the original Finger Engine itself. The idea was to make a powered finger that would drive the Finger Engine just as a living finger does. That is, it would have to push down on the Finger Engine's lever at the right times and just idle on the lever during its upstroke.
This suggested a microcontroller as a 'brain' for the artificial finger. A microswitch linked to the finger sends a signal to a PicAxe mc near the upper extreme of the lever's travel. The mc makes a note of this, so to speak, but waits until the switch opens, which signals the beginning of the downstroke. The mc at that point energizes a solenoid giving a downward impulse to the finger to keep the Finger Engine going. The length of this impulse is adjustable via a resistor that the mc reads every now and then. The solenoid is an off the shelf unit but was rewound to give a satisfactory pull from a 5 Volt supply. It can thus be operated from a power bank as in the video or from a computer USB outlet as well.
Of course, this is another of my useless projects, but the challenge was there, so I did it. And the Finger Engine itself can still be used with my own aged finger just as before whenever the fidgets call for it.
Directions for making the original Wooden Finger Engine can be found at:
www.instructab...