| 摘要 |
PURPOSE:To check the voltage varying state of an IC pin visually and to reduce the production cost of a display device by forming a pin connecting means, a switching means and a display means. CONSTITUTION:Each of amplifiers S1-Sn is constituted of an NPN FETT2 of which emitter is earthed and bias resistors R1-R3. When the measured side final FETT1 which is an IC is in the connected state and the voltage of a resistor R connected to its collector is dropped, the FETT2 is low, and LED elements L1-Ln are turned off. When the FETT2 is in the disconnected state, the base voltage of the FETT2 is turned to high voltage, so that the FETT2 is turned to the connected state and its collector current turns on the LED elements L1-Ln. Thus, the voltage variation of the observed side can be simply checked by ON or OFF of the LED elements L1-Ln visually.
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