How to make a 12-volt LED blink
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A 12-volt LED blinking circuit is more useful than the simple toy or decoration that most LED blinkers are. Car batteries produce 12 volts of electricity. By building a simple 12-volt LED blinker circuit, you can install a blinking red LED on the dashboard of your car.
By installing this blinker, you can create the impression that your car is protected by an alarm system.
Put your operational amplifier, or op amp, into holes in the perforated circuit board. Touch the tip of the soldering iron to the leads of the op amp where they protrude from the bottom of the board at the same time that you touch the solder to it. Hold the solder in place until it melts and coats the lead. Remove the soldering iron and allow the solder to cool.
Put one lead of the resistor into a hole of the circuit board next to the positive input terminal of the op amp. Put the other lead into a hole next to the output terminal of the op amp. Solder these leads to those terminals.
Put one lead of the 60,000 ohm resistor into the circuit board next to the positive input terminal. Place the other lead in a hole close to the edge of the circuit board. Solder the first lead to the positive input terminal. Solder the second into place on the board.
Solder one lead of the capacitor to the free lead of the 60,000 ohm resistor. Solder the other lead of the capacitor to the negative input of the op amp.
Solder one lead of the 75,000 ohm resistor to the input terminal of the op amp and the other to its output terminal.
Place one end of the jumper wire into a hole next to the soldered-together leads of the capacitor and the 60,000 ohm resistor. Solder it to them. Place the other end in a hole next to the negative voltage terminal of the op amp and solder them together.
Remove 1 inch of insulation from each end of each wire with the wire strippers. Solder one end of one of the 6-foot wires to the negative voltage terminal of the op amp. Solder one end of the other 6-foot wire to the positive voltage terminal.
Put the LED into the circuit board. Solder a jumper wire between one of its leads and the output terminal of the op amp. Solder the remaining jumper wire between the other lead of the LED and the negative voltage terminal of the op amp.
Place the circuit board on the dashboard of your car. Run the 6-foot wires under your dashboard and into the engine compartment. The method of doing this will vary depending on the make and model of your vehicle. Consult your owner's manual. Disconnect the cables from the battery. Place one of the wires on each terminal and reconnect the cables. The LED will start blinking on and off a little more often than once every second.
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