Brownout Voltage Tester

Most well designed line powered products can tolerate a wide variation of AC voltages.  But, some circuits are less tolerant.  The hobby circuit below can be used to test a circuit’s ability to operate under low (brownout) AC line conditions.  The electronic circuit shown below uses a filament transformer to “buck” the normal 120vac line voltage down to about 95 volts.  A similar circuit could be used in other countries with a 48vac transformer.  Such a transformer would lower the test voltage from 240vac to 192vac. With the components shown, the schematic has a load rating of 250 watts. 

Click on Drawing to view PDF