I am working on a design that involves powering a 3.3V microcontroller off a doorbell transformer but I am running into an issue with the bridge rectifier failing when the AC inputs to the rectifier are shorted.
There are two basic parts of the design. First, a full-wave bridge rectifier is used to convert the 21V AC supply from the doorbell transformer to roughly 26V DC. A switching regulator is used to deliver 3.3V for powering the microcontroller. A smoothing capacitor reduces the ripple created by the bridge rectifier. That part of the circuit is working as expected and the microntroller can be powered from the doorbell transformer.
The second part of the circuit is simple. To allow the doorbell to be used normally while powering the microcontroller, a switch shorts the AC inputs. This closes the circuit and powers the solenoid in the doorbell that sounds the chime. The issue I am running into is the bridge rectifier failing when the switch is pressed.
I would really appriciate any insight into why the bridge rectifier fails and how the circuit might be modified to prevent the failure.
Bridge rectifier datasheet: DF206ST-G