Top circuit tests voltage of power line transformers. Left transformer is 1:1 isolation transformer for power line voltage. Not shown is fuse before left SPST switch and second fuse between isolation transformer secondary output and current limiting 25 watt lamp. Unknown transformer is on the right with AC voltmeter connected to secondary of tested transformer. Note proper safety needed on high voltages. An old TV transformer may put out 800 volts!
Bottom circuit tests current rating of power line transformers. Left transformer is 1:1 isolation transformer for power line voltage. Not shown is fuse before left SPST switch and second fuse between isolation transformer secondary output and primary of test transformer (current limiting 25 watt lamp is disconnected out of circuit). Unknown transformer is on the right with AC voltmeter connected to secondary of tested transformer. Note proper safety needed on high voltages. Increase loading on each winding with power resistors until voltage drops 10% from no load voltage.
