High pressure alarm circuit


Posted on Mar 28, 2007

High pressure alarm High sensitivity, high-voltage electric energy in the body from lOkV 2m at or away from the low-voltage mains (AC 220v) 0.3m at the alarm device yuan less device, the circuit is simple, easy to manufacture, small in size, easy to use.


High pressure alarm circuit
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Schematic circuit alarm 13120 is shown in Fig. Field effect transistor is a field effect transistor VT1 device when its gate near the electric field due to the induced electric field generated gate bias. Drain-source on-resistance between the emergency will increase, corresponding inputs Dl showed a high potential by Dl, D2 vibration constituted oscillator start-up, resulting in approximately lkHz audio signal, the signal by VT2 amplified speaker sound an alarm input . Dl, D2 using two sets of four-input NAND gate 74HC20 (74LS20). The remaining components of the reference model icon or parameter selection. The machine can be installed in the portable radio cabinet, on the VT1 gate pad section lOcm long plastic soft wire, extending outside the case for the electric field sensor chip used. After the assembly, which was close to the 220V AC power supply line, a speaker alarm sound is working properly, it can make use. To ensure safety, the alarm fulfilled prior to use electricity, which is close to 2ZOV AC power supply line, such as the alarm can be used.




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