AC Scanner. Simple Design 11

With a single IC you can make a simple Non Contact AC tester. Just move in front of an AC wire, switch board etc that carrying AC, the LEDs in the circuit runs indicating the presence of AC in the wire.
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Blown Fuse Indicators. Simple Design 10

Generally a Fuse is added in the power supply positive of many DC operated devices to protect them from high voltage surges. But when the device fails, we have to check the fuse to see whether it is good or blown. We can add a simple circuit to show the status of Fuse. The circuit can be hooked to the output of the power supply. Here three simple Blown Fuse Indicator circuits are given.
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Over Voltage Protector. Simple Design 9


This is one simplest form of Over voltage Protector for the Bread board power supply. Usually we use 12 volt DC power supply to power the bread board. If the CMOS devices are used in circuit assembly, over voltage can damge them permanatly. This circuit limits the voltage to the bread board to 12 volts. If the voltage increases above 12 volts due to a high voltage surge in the AC lines ,the circuit cut off the power to the bread board. It can also be used in any device like Chargers that works on 12 volt DC .
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