range switch

Probably these switches were here in such abundance because they used a longer range switch normally-maybe a thousand miles.

The two outer pads take leads from the two pole contacts (tags) of the range switch.

Switched-mode power supply units (PSUs) in domestic products such as personal computers often have universal inputs, meaning that they can accept power from mains supplies throughout the world, although a manual voltage range switch may be required.

Potential difference of amplitude appearing across the entire secondary of the source transformer T 1 is connected through the unknown impedance Z 1 to the whole, one-tenth and so on tappings of the upper primary of the detector transformer T 2 through a range switch.

Note that when an inductance is responsible for the reactive part of the unknown impedance Z 1, it is given by, where C is the effective value of all the standard capacitances taking into account the tappings of the source and detector transformers at balance and the position of the range switch.