Testo 755 series current voltage testers testo 0590 7551 the testo 755 1 currentvoltage tester is fast and easy to use especially when you are testing multiple circuits the convenient open jaw current tester automatically turns on when the voltage exceeds 6v it then auto selects the correct parameters and range for your testthe rugged tester is suitable for virtually all your daily electrical measuring tasks as it includes all the basic functions eg current voltage resistance and c