Digital counter bell

Development.

The goal was simple; create a stealthy counter bell that can play any sound its owner desires. After having created a prototype using a toy (remote) car key I searched for a customizable solution - I wanted to be able to play any sound. As luck would have it, DFRobot had created a tiny MP3 player that didn’t require a separate microcontroller to run, and could easily be powered by a battery. 

Bill of materials:

• DFRobot DFPlayer mini

• 150mAh Lithium Ion battery

• USB Battery charging module

• Momentary limit switch

• 3W speaker (from an old PC)

• Some wire

The challenge was to find components that fit in the very limited space, were compatible with one another and didn’t take away from the experience. For example, the speaker needed to be loud enough but was not only limited by the space, but also by the maximum output of the DFPlayer.

In order to keep it looking like a regular counter bell, I wanted to make sure to keep the bell intact and designed a base plate that would hold everything in place, and also to keep things nice and tidy. I also fashioned a mount for the switch so that it would be at the right height to accommodate for the bell’s original “button”, to once again, give the illusion that it was an ordinary counter bell. The laser cut base plate and the switch mount (and some spacers) were secured with a couple of longer M3 bolts, using the pre-existing holes in the bell’s metal base.

Extremely satisfying having it all come together perfectly. My plan has always been to take it one step further and make a customizable and super affordable door bell.