Test device for simultaneously displaying the level of logic signals in a plurality of circuits

摘要

A test clip suitable for connection to a plurality of terminals at which appear respective logic signals representing those occurring in logic circuits provides an indication of the logic level of such signals. The circuit for effecting such indication is entirely self- contained requiring no external power source or grounding connection and includes a plurality of respective input lines connectable to such terminals with a respective indicator shunted by a reverse poled diode connected to each input line and one common connection for all the diodes and indicators. Thus, for example, a logic 1 signal occurring on one of the input lines will effect a current flow through a respective indicator to change the state thereof with a return current flow path being provided from the common connection through at least one of the shunting diodes connected to another input line then at logic 0 relatively ground potential. The circuit may be easily extended to test simultaneously as many circuits as desired, and such test circuit is effective to operate on positive logic as shown as well as on negative logic, the latter being achieved simply by reversal of the shunting diodes.