Hotel key-card power switch

When I was a student, I spent one summer working for IBM. We had this stuff called 'MagaSee' which you sprayed onto magnetic tape to reveal the data tracks. I remember one of my colleagues sprayed this stuff onto my door entry card and it revealed a number of magnets embedded in the card, in different orientations I was told, so that the reader could distinguish which card had been inserted. I suppose nowadays, this would be done using RFID chips..

Gordo

My go to hotel in Bangkok used an even simpler version which was just a microswitch and lever that made contact when the card was pushed in so easy to use any card or bit of cardboard. As they only wanted to turn aircon & TV off when the room was not occupied it did not control the lights. Of course most people figured it out and left their aircon running. Last time I was there they had changed the units to one which seemed to use magnets, reed switches (or hall effect sensors) and a card with metal strips in it. I'm assuming that the metal strips in the card 'carried' magnetic flux over a cm or so to the sensor. This cunning change meant that the room was stifling each time you came back to it (they also welded the spring loop that connected the card to the room key so you could not detach if from the keys!)

Mr B Shepherd

This what I do, I always stick my tesco club card or anything else in the slot and leave the lights and heat on. Yeah bad for the environment but keeps it at the right temp all the time I am there!

Well, in the case where you only have one key card, use a business card or a folded piece of paper. These readers don't actually read anything on the card you insert. I have done this a few times to cool down the room with the A/C unit while having dinner somewhere.

Tobi

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Big Clive

I hate those bloody card readers. Myself and an ex used to travel a lot to go to concerts and most of the time we'd stay in the cheapest hotels we could find. These hotels would only supply one card to let you into the room and provide power. As a smoker (I know, smokers are jokers etc) I'd have to leave to room multiple times and would either have to knock on the room door to get back in or take the one card with me and leave her in darkness......that was not advisable! It got to the stage that I'd demand a second card on check-in. Some of the places we'd stay would charge a deposit for a second card.

John Carr

While staying in a German hotel a few years back, I had a faulty travel adapter that tripped the RCD. When I reported the issue, a staff member took the picture off the wall outside my room, revealing the room's consumer unit and flipped the RCD back on. Useful to know. 😉 In another hotel, the air conditioner remote didn't work and the AC was running full blast and had no onboard controls, so I found its breaker in the room's consumer unit (in this case easily accessible in the room) and flipped it off until the morning.

Seán Byrne

I was with a group of people traveling internationally and after check in half the group came out of their rooms to complain the power was out. I would have done the same thing but a long time ago when I was first checking into a hotel room internationally someone showed me this “feature”.

Lostngone

Great teardown, Clive. Quite enjoyed that. A nice, economical design. I saw the SMT zero ohm link LOL. I don't think 80 deg C is all that bad. It passes the Henry Ford test haha. Those high current terminals look like a weak mechanical link. Enthusiastic tightening is going to stress the solder weld unless they are well held in the moulding. UPDATE - I'm mistaken about the screw terminals. They should be fine as long as you're working dead.

Mike Page

It keeps the air-con on as well.

Malcolm J Bannister

No, it can be anything. Sometimes I use another card, e.g. if I need to charge my laptop, and the outlet is turned off by this device.

Rasmus

Your timing is perfect sir. Thank you!

Michael Thompson

It seems that anything opaque that fits in the opto-switch would trip the relay - doesn't have to be a hotel card, or is there another sensor?

Christopher Seal

Clive, I ran in to these switches on a trip to Kyoto Japan a few years ago. Quite interesting. I am guessing a good use for power management.

Chris Muncy