Place the part that is to be demagnetised on the demagnetiser, connect it and drag it over its surface until it is 30 cm from the demagnetiser. Then without bringing the part close to the demagnetiser, disconnect it. If the part is not totally demagnetised, repeat the same steps.
These demagnetisers are for intermittent use. They should not be connected for more than 10 minutes. They have an incorporated thermostat which disconnects them when they reach the maximum admissible temperature.