First post, please be gentle.

I have an electric kettle that turns off when the water boils, but gives no indication that it has done it's job. I would like to figure out how to wire up a bell that will chime once when the pot is no longer drawing current. I assume my best plan of attack would be an AC relay that would trigger the bell, perhaps using a 555 chip, but beyond that, I'm out of my depth.

Any help would be appreciated,

Justin

 

A current transformer threaded onto the mains supply lead?

...or perhaps just simply wrapping a few turns of wire around the mains supply lead and amplifying the signal?

Just some ideas.

 

If there was room, and a mechanical thermostat, a buzzer could be connected across it.

It would remind you to unplug it, as it would buzz until disconnected.

A diagram in another thread shows a dryer buzzer connected that way.

http://www.freeinfosociety.com/elect...ew.php?id=1564

 

Microswitch actuated by the pop-up lever on the kettle switch?

 

Whistle on the spout?

 

Alas, the design of the kettle precludes a whistle. I was hoping not to modify the kettle itself, rather make a box with a socket that the kettle would plug into.

Would a 555 be cooked if the switch was normally in the "on" position and turned off only when current was flowing?

 

Would a 555 be cooked if the switch was normally in the "on" position and turned off only when current was flowing?

You'll need to explain that. Which switch are you talking about? One at the mains socket, or in the kettle, or for the 555 supply?

 

My idea was to have an AC relay open the trigger switch for the 555 when the kettle was drawing power and close it when it shuts off. This would mean that the 555 trigger would be normally closed, except when the kettle was in operation. Is this clear?

 

Much clearer . What will you use to power the 555 and 'bell': batteries or wall-wart?

 

wall-wart, I've tons kicking around.

 

And how is it you plan for your 555 to know that the kettle is on as opposed to just plugged in?

I can't help but believe there is a way to use the water temperature or steam temperature more easily. Even if it was only a thermistor positioned over (or on) the kettle spout.

 

If you are always heating the same amount of water, a timer would do the trick.

Bob

 

Start with one of these..................................

 

The kettle probably uses a thermal snap switch to control temperature. Using it to also trigger a buzzer, through a relay, should do what you want. If it doesn't use a thermal snap switch, adding one to trigger the buzzer directly could also be done. The snap switches are available in many different temperature ratings - http://www.comstatinc.com/thermostats/snap-disk You can even get them on Ebay.

 

Start with one of these..................................

These look just what I'm looking for, a little pricey, though.

My hesitance to modify the kettle itself is that the kettle sits in a base where it gets its power. With this design, the wiring stays behind when the kettle is carried to the tea pot or coffee cone.

 

Personally I'd go with Tracecom's suggestion (post #11). A matchbox-sized gizmo could hold a bit of circuitry, beeper and couple of CR2032 batteries and hook over the spout, with a thermistor in the hook.

 

Smart power strip.

Plug kettle into main outlet.
Plug a 9vdc battery powered "not" buzzer into a slaved outlet.

ps.
Anyone hacked one?
Power rating?
Internal relay with a nc. contact?

 

These look just what I'm looking for, a little pricey, though.

My hesitance to modify the kettle itself is that the kettle sits in a base where it gets its power. With this design, the wiring stays behind when the kettle is carried to the tea pot or coffee cone.

If the kettle gets it's power from the base, I would think you'd include a current sensor in the base or added to the base. That way per your requirement you would not be modifying the kettle (pot). Or am I misreading that restriction?

 

If the kettle gets it's power from the base, I would think you'd include a current sensor in the base or added to the base. That way per your requirement you would not be modifying the kettle (pot). Or am I misreading that restriction?

I wonder if the thermostat is in the base.
A buzzer across the thermostat is still the simplest.

 

Added links..........................................

Use a smart outlet strip.
Aux. outlets power on when there is a load on the main one.


http://www.walmart.com/ip/CyberPower-7050SG-7-Outlet-Surge-Protector/14968093?action=product_interest&action_type=title&placement_id=irs_top&strategy=PWVAV&visitor_id=63282949131&category=0%3A3944%3A3951%3A132959%3A4483&client_guid=a4419f26-f848-400c-bf49-3424ccdb2c80&config_id=2&parent_item_id=11962569&guid=5e045b8c-478b-41ae-963b-b89b2da9cc21&bucket_id=irsbucketdefault&findingMethod=p13n#Product+Reviews



Then plug in a power failure alarm.
http://www.ebay.com/itm/Super-Loud-...209?pt=LH_DefaultDomain_0&hash=item4ab2750c49