Smart Touch Switch Door Bell Project | For 10th Class Science |  

This was fun to see. I just made my own doorbell myself. I was jealous of the RGB doorbells I have seen but none make me happy. Designed my own. I use an ESP32 for the doorbell, then another ESP32 downstairs where the transformer and wires are. A diac/traic pair switches the AC on and off to the ringer upstairs. I added an adressable ws2812 ring light from Amazon. Then put it all in a 3D printed package I made to look reminiscent of an old fashioned camera. It looks like you are using a 555 timer to make the square wave for the buzzer to do it's thing? I love the 555!! An upgrade idea to get rid of bulk and get rid of the click... You could eliminate the relay and use a NPN BJT, like a 2N2222 or a 2N3904 (and one resistor, say about 10K ohm) in it's place. You would be switching ground to the buzzer with the transistor and square wave would be unswitched on the other buzzer pin. Without ground, no sound. Stick the transistors emitter to ground, the collector to the buzzer, and the base (through a 10k input resistor) to your touch switch. Have not tried it but I think it would work just fine. To turn on apply a few volts to the base, connecting ground to the buzzer. The emitter would be floating when off, since there is no pull-up resistor. Therefore, no current would be able to get through the buzzer from the 555. I think if you used a pull-up resistor to Vcc on the collector, considering that piezo buzzers are not polarized, when the 555 went low it would allow current to pass in the opposite direction making the buzzer buzz. So long as the pull-up resistor is not too high a value and block too much current. Quick back-of-the-napkin math says anything larger than, roughly, a 360 ohm resistor @ 5V (if you are not at 5v then just use ohms law to find your number) would probably prevent the buzzer from buzzing if you needed to have the BJT's collector NOT floating. I would use a 10K just to be safe. Love seeing other people enthusiastic about electronics. It is so satisfying to think of something you want to do, plan and design it, build it, and watch it work. Such a thrill. Stay curious and make lots of mistakes! (it's how you learn!)