Control Units such as those supplied by ROMPA® have an outlet at the back into which you can plug an adapted toy, so that the toy will operate when a switch lead is plugged into the front of the Control Unit in the usual way.
(The great advantage of this is that you are able to use the same modes - 'momentary', 'latched', 'timed' etc. which you were using with the mains-powered equipment.)
For safety reasons, this is a female outlet, so you will need to have fitted a male jack plug to your toy if it is to work from the Control Unit.
If you want to operate your toy from a Control Unit, but you also want it to operate directly from a switch when the Control Unit is being used by other students, do this.
1) Fix a 'male' jack plug to the lead from your gadget.
2) Make yourself a short female adaptor lead, as in the picture. When operating the toy from a Control Unit, you will not need this adaptor lead, but if you want to run the toy directly from a switch, these two 'females' will enable you to join together the two male leads.
A word about jack plugs. A simple jack plug [3.5mm] has two terminals at its end, one being the side shaft, and one being the nose. Most switches are supplied with two-terminal jack plugs, and these are the switches you will have in mind if you want your student to operate the adapted torch, car or somersaulting dog directly from the switch.
You will find that a few switches are supplied with three-terminal jack plugs on their leads - that is, a nose, a collar, and the side-shaft. This usually means that the switch is designed with some clever and complex circuitry, and is intended for use with equipment which can interpret that circuitry, such as a Control Unit.
In brief -
Fit two-terminal male or female jack plugs to your battery-powered equipment.
Operate the equipment with switches which have two-terminal jack plugs on their leads.
or Operate the battery-powered equipment through a Control Unit, in which case you can use any switch and any jack-plug.
The switch socket of Control Units, such as that supplied by ROMPA®, will happily accept both two- and three- terminal jack plugs
Booklet reproduced with kind permission of Chris Addis and ROMPA.