November 28, 2012 AT 10:01 am

Arduino-powered Audio Doorbell

Check out this excellent audio doorbell project created by Adafruit community member Jarruda — with a little help from the Adafruit forums!

So when I bought my house, I noticed it had probably the most boring doorbell on the planet. Then I saw the Adafruit’s Wave Shield and saw inspiration. This is my first actually completed hobby electronics project, so I’m pretty proud of it, even if it’s really simple.

Main Parts:

Power for the doorbell comes from a 16V transformer off mains power (120V). It’s run through a 50V 4A bridge diode rectifier into an electrolytic cap and a ceramic cap to smooth the pulsed DC, then two diodes to drop the voltage by ~3V before powering the mono amplifier and being split off for the UNO’s Vin.

The doorbell is connected like any other button, sending 5V out to the doorbell and in to a digital pin configured as an interrupt. Using a pullup resistor and pulling the pin to ground wasn’t used to lower the demand on the linear regulator running on voltage that’s a bit higher than I’d like. To further reduce power usage, the atmega328 is put into PWR_DOWN sleep in between doorbell rings.

Also, thanks to adafruit_support for providing help!

My next project is a little more ambitious, a thermostat that can use a wireless sensor for temperature readings.

Read more.

Guts of Audio Doorbell

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