Readers are provided with a simple probe-generator for "continuity test" cables and electrical circuits, which used damaged wrist electronic watch.
It is known that liquid crystal display (LCD) such a clock is powered by a signal source with a frequency of 512 Hz. He serves as a signal in the poll. For the manufacture of the probe must be removed from the watch the LCD when the power is turned on with using headphones to find a contact on which the signal frequency of 512 Hz. Most hours is one of the conclusions of chip capacitor. To fixed solder contact probe (see picture) and the probe is ready. The volume of its sound is quite sufficient for continuity.
The feature of this probe is very small size and high efficiency. In mode continuity test from the battery voltage of 1.5 V it consumes a current of 0.7 mA.
Author: R. Zhukov