Hager Key Card Switch Proftech

Hager Key Card Switch are often furnished with an interior key-holder near the main door which enables the ac power supply to everything in the room only when the key/keycard is hanged/inserted. The circuit given here to flip electric lights (and other appliances) is along the same lines, but the solution is amazingly simple and inexpensive!

key card switch bump switch (S1) is attached to the circuit, and its long lever arm is extended to the outside such that when the key card is hanged on it the bump switch is closed. Now, the electromagnetic relay (RL1) will pull in and complete the circuit for all the ac-powered appliances in the room. As soon as the card is removed,the bump switch will open, and this in turn releases the relay contacts. Various connected appliances will automatically (and inevitably) be switched off after a short delay when the room key is picked up from the key-hanger.

key card swich circuit should be fitted in an insulated enclosure, since it is connected directly to the ac powerlines. Note that the coil of relay RL1 must be have a low operating current (no more than a few dozen milliamperes). The author used a type HRSS 4H-S-12V DC (from 3NIX) in the prototype. The 3NIX sugar cube relay draws near 26mA at 12V DC.

At first glance, many readers (and evaluators) might think this circuit is superfluous because only one heavy-duty bump switch can play the game well. Yes, but it is highly-flexible and leaves enough room for expansion. An interested hobbyist can make numerous modifications like key-card based activation, remote switching control, etc (ofcouse using galvanic-isolators) without too much difficulty.

Specifications

• 50 x 50mm Euro Module
• Load Rating – 1800W for resistive, 800W for inductive
• 30 second power-off delay
• Locator LED
• Mounting box depth 47mm
• Colour coded terminals with backed-out and captive screws
• Designed and manufactured to BS EN60669-4
• Supplied as kit of Euro Module components