| 摘要 |
Testing device for indicating electric voltage, polarity, and for continuity testing, including: two handles connected by a cable and having test prods; high-resistance series resistors connected to the prods; indicating stages having optical indicating elements with staggered voltage ranges in one handle; an oscillator connected to the indicating stages and to an acoustical signal generator; an isolation amplifier connected between the indicating stages and resistors; a battery connected to the amplifier and activatible by the amplifier; a switching power supply connected to the oscillator; an energy storage device connected to the amplifier; a first switch connected to the battery; a second switch connected between the power supply and the storage device for feeding voltage in a rest position, when the storage device is charged and being switchable into contact for feeding a charge to the amplifier and for checking operability in sequence; transistors having bases connected to the oscillator for intermittently switching on indicating current for optical elements for a brief time for higher voltages and for optical elements for lower voltages; a Zener diode connected between one resistor and the first switch; the first switch being switchable to rest position for shorting the diode and into contact for switching on the battery, for continuity testing through a conductor between the prods and internal testing for direct contact between the prods for the battery, the signal generator, an optical element for polarity, another optical element for battery voltage and charging of the storage device.
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