How do I measure the voltage of my doorbell transformer?
How to test a transformer with digital multimeter and oscilloscope. - YouTube
Kungber DC Power Supply Variable, 30V 10A Adjustable Switching Regulated DC Bench Linear Power Supply with 4-Digits LED Power Display 5V/2A USB Output, Coarse and Fine Adjustments with Alligator Leads
Amazon.com: Kungber DC Power Supply Variable, 30V 10A Adjustable Switching Regulated DC Bench Linear Power Supply with 4-Digits LED Power Display 5V/2A USB Output, Coarse and Fine Adjustments with Alligator Leads :