A friend had a non preforming bobble head 15 in owl & wondered if the head could be randomized? With out much thought , sure why not, just a motor & some IC's. Two months later he has his owl back with random motion head & LED illuminated eyes.
I thought that maybe some of the circuits may be of use to some body
The random number gen. uses a 556 as a fast ( 1 m. ) & slow (16 m. ) clock driving a 4518 4 bit counter, which was later changed to 3 bit to limit head to 8 positions. The random count is helped to keep random by introducing some noise on 556-3 control pin by use of a blinking LED's PWM signal. The 3 bit number is gated to allow a stable input to a 74LS85 digital comparator. The other input number is derived from a GRAY code disc which is attached to the motor shaft & to head. When a number is selected & it is larger than Disc, the motor rotates until the numbers agree & stays for 16 min. The counter counts for 1 min. & comparator inputs are 0, head returns to home position for 1 min.
IC U5 converts Gray to binary.
The motor is controlled by an H bridge using LL SM FETs. on same solderable breadboard as ICs. Gate drive & inversion by 74AC00. To prevent any possibility of both drive signals being high, U5-A & U7-A & B are used.
The photoreflective sensors have a slot which allows stacks to be screwed together. The photo transistors are operated as common collector with 100k emitter loads. U6 is for impedance reduction
The motor connects to the head by using concentric square shafts. Slip rings for eye power were built but not used because of installation problem. If comparator cannot find a match in one rotation, then motor will rip out eye wiring. View attachment 115831
An error occurred in redrawing ckt. of H bridge.

 

Is this one those owls used to scare birds away? I see them on docks. Scared me the first time I saw it move!

 

That is the intent; just hope that Mr Motor head is more effective.