Single rotate mechanism

This is where it gets a bit tricky!
There are a number of mechanisms employed by Mousetrap that I tend to regard as 'Standard' but which may be very new to some Spanners. The first is one I call a 'Single Rotate Mechanism' whose output shaft is designed to rotate just once. This output shaft may, or may not, allow one or more 'Pulses' to be output which drive mechanisms similar to itself.
This picture (and the next one) show a demonstration mechanism that employs standard micro switches that may be obtained from Maplins. They are particularly useful since they have ready made attachment holes which are almost exactly one inch apart and are easily bored out to 4mm. The two pics should be viewed together if possible. Ignore the switch furthest away from the flanged plates together with its yellow wiring for the moment, and concentrate on the other switch and terminals A, B and C. Also ignore the white wires to Terminals B and C.
The wiring is as follows:
Motor -ve to Terminal A (Black)
Motor +ve to Terminal C (White)
Switch Common to Terminal B (Red)
Switch (1) to Terminal C (Red)
6 volt -ve to Terminal A (Blue)
6 volt +ve to Terminal B (Red)
Now, if the lever of the switch is in the raised position then the motor receives current and the output shaft (with the 19 tooth gear) rotates clockwise.
However, if the lever is depressed then no current flows and the output shaft stops.
Now consider the 1/2" bolt in the collar just above the switch. This is adjusted so that as the shaft rotates this bolt will depress the lever and so cut off the current and so stop the motor.
It should now also be noted that if Terminals B and C are shorted together, then current also flows and the motor will start.
OK. Now bring in the two white wires. If these are shorted together for just a short time (say <= 1 second) then the output shaft will rotate long enough for the 1/2" bolt to stop depressing the lever, normal current will flow and the output shaft will make one complete revolution before the bolt once again depresses the lever.
Good. So far we have a mechanism that will allow an output shaft to rotate exactly once.
Now consider the second switch. This is wired as follows:
Switch Common to Terminal D (Yellow)
Switch (2) to Terminal E (Yellow)
It is now fairly obvious that the second 1/2" bolt above the second switch can be used as a source of a 'Short' or Pulse, when its lever is depressed, to provide input for a following mechanism similar to this one. In fact the output shaft can be used to provide any number of pulses. For example, Mousetrap uses a mechanism that provides for up to five pulses.
When I first designed this mechanism (it seems ages ago) I built two and coupled them together to provide pulses for each other and watched them for ages!
This, however, will now be left as an exercise for the student (as I used to say in my lecturing days!). Anyway, build it if you like - it's very useful.
The next picture shows how they are used.