CONVERTING AN OLD CONTROLLER.
Basic pulse controllers for low voltage are fairly cheap and readily available. All that is required to make a controller is a reversing switch and an auto resetting cut out. The latter can be a sperate unit, although the facility is provided on some control units. Some units even include an on/off reversing switch as well. A useful addon is a voltsge/amperage display.
MAKING A CONTROLLER FROM SCRATCH
Any suitable box will do and the controller can be either buit from scratch or purchased as a ready made unit.
12 volt DC SUPPLY
There are many units available. In practise a 15 volt unit may be of more use as this allows for any losses within the controller unit.