How would you make a 120VAC powered beep/chime ?

[Externet]

Hi.
For an elderly person that forgets to turn off the electric stove; I would like to add inside the control panel, a periodic beep once a minute as a reminder when a 'burner' is on.

Without adding a low voltage power supply, tapping from the neon 'ON' indicators, when energized, something that makes a brief noise every minute would be great. How would you do it ?

Obviously, a piezo buzzer or speaker would not handle high voltage, plus a 'timing' something would be needed...

 

[Harald Kapp]

Without adding a low voltage power supply,

This is imho the most simple and least dangerous method: Connect e.g. a USB wall wart's input in parallel to the indicator. Use the 5 V output to power a simple timer, e.g. based on a 555 and a piezo buzzer for output. The only safety relevant connection you'll have to make is from the indicator to the wall wart. Everything else is low voltage and safe.

 

[73's de Edd]

Sir Externet . . . . .

Use this line powered circuit or hand fabricate a NE-2 to photocell optocoupler interface to trigger a separate LV powered beep circuit. . . . . . (I still like NE-2's and NE-51's for certain applications . )


A higher C! capacitance gives more " PUNCH " to the beep.
Increasing R1 resistance or increasing Cx capacitance spreads out the time between beeps. . . . . with a higher value of Cx giving a louder beep.

73's de Edd

 

[Externet]

Thanks, gentlemen.
Harald : That was my second choice to do it, by powering a USB cube adapter directly from the neon indicator in the stove panel.
Edd: That is what I envisioned, but I was wondering if a diac would be implementable. Your Ne-2 would work as a relaxation oscillator until 100n depletes; right ?

I will digest a combination of both to avoid a burst generator (Ne556) circuitry... Will see what contraption comes out.