Square wave output:the frequency is 50Hz,the voltage is approx 3Vp-p.The output jack is "V ohm mA" and "COM" When testing the magnifying ratio of the transistor ,turn the switch tohFE position and connect the transistor to the eight hole jack. When testing the current more than 200mA, connect the red test lead to OADC jack and black test lead to COM jack. ome with buzzer, pocket and easy to carry, cost efficient.