If the wifi doorbell camera is not properly powered by your current transformer and you are using an older chime doorbell, we recommend the following doorbell chime that includes a transformer. Please see the links to Home Depot and Canadian Tire. We have had a few customers replace their transformer and chime with this product successfully.
To locate the power transformer for your current doorbell, it may be in the basement near the fuse box or in a closet or storage room.
Canada
Heath Zenith Wired Door Chime Kit With Two Push Buttons
US
Heath Zenith Wired Door Chime Kit With Two Push Buttons
You can also check out your local hardware store.
Installation Guide
https://www.youtube.com/watch?v=vPfQM24N5YQ
Replacing a Transformer
https://www.youtube.com/watch?v=867nCCONKs4
Ensure that you install the Chime kit (included with doorbell camera) Unlike a regular doorbell push button is wired in the normal open circuit position, a wired doorbell camera is in the close circuit position as it needs constant power hence the chime kit serves as a load resistor to the doorbell chime.
IMPORTANT: Using a transformer that's voltage is to high or improperly connecting the chime kit to the mechanical chime can cause the Doorbell camera Chime kit to bloat and overheat. Ensure to use a transformer, as recommended above that is between 12-24V
OSI Doorbell Camera installation video