How to Rewire a Car Lighter Adapter Plug

How to Rewire a Car Lighter Adapter Plug

Portable electronic appliances typically come with 12-volt adapters and patch cords that enable such appliances to be used inside vehicles. In the United States, production of 12-volt automobile plugs is standardized under "UL standard 2089," which covers plugs and patch cords that insert into cigarette lighter receptacles. A 12-volt car lighter adapter plug is easy and convenient to use, but can sometimes become defective due to abuse or misuse. If you know how to rewire a defective car lighter adapter plug you can save yourself some cash.

Things You'll Need
Diagonal pliers
Wire stripper
Soldering gun
Solder wire


Instructions
Cut the cord attached to the lighter plug about 2 inches below the plug, using diagonal pliers. Remove about 2 inches of outer covering from the tip of the patch cord, using diagonal pliers. Strip off 1/2 inch of insulation from the tip of the two inner wires (positive and negative), using a wire stripper.

Look at the plug. Observe the two retractable metal fins protruding on each side of its cylinder, and the retractable metal nipple at its tip. Note that the side fins are negative conductors, and that the tip is the positive conductor of the 12-volt circuit.

Hold the plug cap in your right hand, hold the cylindrical body in your left hand, and twist the cap counterclockwise to unscrew the cap from the plug's cylindrical body. Find the holding screw along the adapter plug's cylindrical body, and unscrew it with a screwdriver. A lighter plug is typically split lengthwise along its center into two identical halves. Open the cylindrical body to reveal the metal fins and nipple inside, including a small spring that pushes the retractable metal nipple.

Note the order in which the metal conductors and spring are arranged inside the plug's cylindrical body. Remove the existing wires attached to the metal nipple, and to the metal fins, by cutting the wires using diagonal pliers.

Loop the stripped end of the positive wire (red, or black with white stripe) around the base of the metal nipple (positive terminal), and solder the copper wire to the metal nipple, using a soldering gun and solder wire.

Wrap the stripped end of the negative wire (black, without stripe) around the base of the metal fins. Fasten the wire onto the fins, using soldering gun and solder wire. Replace the metal nipple and metal fins inside the plug, and reassemble the plug in the same arrangement as you had found them earlier. Make sure that the positive and negative wires do not come in contact with each other.

Turn on your vehicle's ignition switch. Insert the car lighter adapter plug into a 12-volt receptacle on your vehicle's dashboard, and turn on your appliance to test the connection.

How to Check if a Diode Is Bad

How to Check if a Diode Is Bad

Diodes are semiconductor devices that conduct current in one direction only, and are commonly made from silicon or germanium. Diodes have two terminals -- an anode and a cathode -- with the cathode being marked by a line painted on the body of the diode. Current is allowed to flow from the anode to the cathode, but is blocked in the other direction. This property is used most commonly in rectifier circuits, which change alternating current to direct current. Diodes are also used to protect components in a circuit if the power is connected the wrong way around, blocking the flow of current to stop damage being caused. Although diodes rarely fail, it can happen if they are exposed to voltage or current above their rated limits.

Things You'll Need
Digital multimeter
Soldering iron
Desoldering braid
Pliers


Instructions
Unsolder one leg of the diode if it is part of a circuit, otherwise the other components in the circuit may affect the results of the test. Heat the solder pad around the diode leg until the solder is molten, and then gently pull the leg through from the other side using pliers. Soak up any excess solder with desoldering braid, leaving the hole clear.

Set the multimeter to its diode test mode, denoted by the circuit symbol for a diode which looks similar to an arrow. If the multimeter does not have a diode mode, set it to the lower end of the resistance range.

Place one probe from the multimeter on to one of the diodes legs, and the other probe on to the other leg. Note the reading obtained, and then swap the positions of the probes and note the new reading.

Interpret the results. If you get an open circuit in one direction indicating the current is blocked, and a low resistance reading in the other direction, the diode is good. If there is an open circuit in both directions, the diode has failed with an open circuit. If there is a low resistance in both directions, the diode has failed with a short. In both cases the diode should be replaced.

How to Identify Diode Markings

How to Identify Diode Markings

Diodes are electronic components that permit the flow of electric current in one direction only, shutting current off when it reverses. These handy devices have dozens of important uses in circuits, including as power supplies and radio signal detectors. Because diodes have polarity, their packaging carries distinct markings that help you connect them correctly in a circuit.

Signal Diodes
The smallest discrete diodes are designed to handle about 100 milliamps of current. These devices are typically packaged in tiny glass cylinders with a connecting lead at each end. A stripe on the cylinder marks the diode’s cathode, making the opposite side the anode. With some diodes, you may need a magnifying glass to see the stripe clearly.

Mid-Power Diodes
Diodes used as rectifiers in small power supplies are usually rated between 1 and 5 amps of current, maximum. These components usually have a cylindrical body made of dark epoxy or ceramic with a white or silver stripe marking the cathode side.

High Power Diodes
Diodes designed to carry more than a few amps of current may get very hot during operation, so they come in standard metal packages that bolt to a heat sink for cooling. Although the manufacturer may stamp a diode symbol on the package, indicating the anode and cathode connectors, you can also determine the device’s polarity by the package itself. Component catalogs and specification sheets indicate the case type and how to connect the diode.

Surface Mount Diodes
In recent years, electronics equipment manufacturers have increasingly moved from traditional leaded components to surface-mount devices, or SMDs. They are less expensive than traditional components, lower in cost and are compatible with the high-speed, pick-and-place robots now common in electronic circuit assembly. Like their cylindrical counterparts, SMD diodes have a white stripe that marks the cathode end of the device.

Light-Emitting Diodes
Light-emitting diodes have similar electronic characteristics as plain diodes; they have a cathode and an anode, and they block current in the reverse direction. They are compact, rugged and efficient at emitting light, making them very useful in such applications as simple on-off indicators, numeric displays, video screens and room illumination. Traditional LEDs have a clear or colored epoxy dome with a flat spot indicating the cathode side. Additionally, the cathode’s lead is shorter than the anode’s. LED arrays and other complex packages follow industry standards. However, if the package is not clearly marked, you may have to look up the part’s specifications in a manufacturer’s catalog.

How to Connect Diodes

How to Connect Diodes

Diodes are semiconductor materials that behave like switches. They are open to electricity in one direction and short-circuited in the other, meaning that current is allowed to flow in only one direction. Silicon and germanium are two materials they are often made from.

The symbol for a diode is an arrow to show the direction current flow is allowed. A diode placed in a circuit this way is known as forward-biased. A diode with current flow in the wrong direction is called reverse-biased. Ordinary reverse-biased diodes will finally allow current when there is too much current flowing the wrong way. When this happens, they are destroyed.

Things You'll Need

Silicon diode, such as a 1N4001

Resistor

Multimeter

Breadboard

Jumper wires

Battery

Instructions

Measure the forward-biased voltage on the diode by placing the multimeter on the diode setting. Put the positive or red lead on the anode side of the diode, which is unmarked. Place the negative or black lead on the cathode side of the diode, which is marked by a stripe. An undamaged silicon diode will read 0.5 to 0.7 when it is forward-biased.

 Forward-bias measurement.

Measure the reverse-biased voltage on the diode by switching the multimeter probes. Place the positive or red lead on the marked or cathode side of the diode. Place the negative or black lead on the unmarked or anode side of the diode. You should get a reading indicating an overload or no current flow.

 Reverse-bias measurement.

Attach a 3- to 9-volt battery to the circuit board. Add a 330 ohm to 1k ohm or more resistor to the positive lead. Connect the anode side of the diode to the free end of the resistor and the other end to the negative terminal of the battery. Note that the diode is in series with the battery and resistor.

 A forward-biased circuit.

Measure the voltage across the resistor by placing the multimeter on a low DC voltage setting, and by placing a lead across each side of the resistor.

Calculate the current in the circuit using Ohm's Law I = V/R, where V is the voltage from the battery, I is the current, and R is the value of the resistor. This mathematical model assumes the diode is ideal and behaves like a switch, so that the load is only across the resistor.

Measure the voltage across the diode. Note that the diode behaves like a 0.7 V battery.

Why Do I Need a Blocking Diode on My Solar Panel?

Why Do I Need a Blocking Diode on My Solar Panel?

Blocking diodes in photovoltaic systems serve two functions. They can prevent batteries from draining at night, and can isolate damaged or under-performing solar cells. The latter can be solved with either a blocking or a bypassing diode.

Function
A diode is a semiconductor device, a one-way valve for electricity. Diodes are rated in the maximum current they can pass through while on and the maximum voltage they can block when off. When the correct conditions are met, the diode will stop current from flowing.

Shaded Panels
Solar panels contain several solar cells wired together in series. If part of the panel is shaded, all of the cells become less efficient.

Bypass Diodes
A blocking diode in the panel "averages out" any shaded cells. The diode allows the loss of voltage from a shaded cell to be shared among the others, so that the panel functions more normally.

Battery Drain
At night, dusk and dawn, the battery outputs a higher voltage than the solar cells do. Without a blocking diode, the battery will send power to the panels instead of the other way round. Over time, this can drain the batteries.

Blocking Diodes
When the battery voltage is higher than that of the solar panel, a blocking diode shuts off flow. During the day, the blocking diode can also prevent drain from the battery caused by damaged cells. In a function similar to bypass diodes, the bad cells are isolated from the others.

How to Choose the Right Diode

How to Choose the Right Diode

Diodes are electronic one-way valves, letting current flow in one direction but not the reverse. If you're designing a circuit that uses them, you'll need to know they have limits. They can handle a rated maximum current, and if you exceed this limit you'll destroy the part. They also have a reverse voltage limit, past which they will start conducting, possibly with damaging results. And diodes come in several different physical case styles, with leads or in a surface-mount (SMD) case.

Things You'll Need

Pencil and paper

Calculator

Circuit schematic

Semiconductor catalog

Instructions

Evaluate the schematic at the point where the diode will be located. Determine the maximum current that will be flowing through that point and write the figure down. Determine the maximum voltage that the diode will have to sustain. Voltages are differences in potential between two points, so if one side of the diode is at 25 volts and the other at 5 volts, 25-5 = 20 volts. Write the voltage value down.

Multiply the voltage value by 1.25 and write it down. Do the same for the current value. These will be your minimum ratings. Multiply the voltage value by 2.5 and write it down, and do the same for current. These will be your maximum ratings. The diode you use can exceed the maximum ratings if you cannot find one that's smaller than it. For example, if your maximum circuit voltage is 15 and the smallest diode value you can find in the catalog is 100 volts, it's perfectly safe to go with 100. Do not use a part rated for less than your minimum value.

Determine how you'll be building the circuit. If the diode is rated for much more than 5 amps of current, it may need to be mounted in a metal heat sink. If you're using surface-mount components, you'll be looking for that style of diode package.

Open the catalog and search through the diode section, beginning with the lowest voltage ratings that match yours, then look for current ratings that match. The catalog will list diode voltage ratings as either Peak Inverse Voltage (PIV) or Peak Reverse Voltage (PRV). It lists current ratings as Average Forward Current, Recurrent Forward Current and DC Forward Current. If the diode is rectifying 60-cycle AC, use Average Forward Current. If the diode will be handling recurring current pulses, use Recurrent Forward Current. Otherwise, use DC Forward Current to find the right diode. Make sure you select a physical package that fits your overall design in terms of leads or surface mount.

How to Use a Diode to Stop Battery Drainage

How to Use a Diode to Stop Battery Drainage

Diodes are used in electronic circuits to prevent electrical current from flowing in more than one direction. They are also used to push electrical current from one point in the circuit to another, such as is the case in a solar cell charging circuit. When a diode is used as a means to control the direction of current flow, it is referred to as a "blocking" diode. When solar panels are exposed to light, these panels generate electricity and can charge a battery. If a blocking diode is not present, the solar panels can also drain the battery when the solar panels are not exposed to light.

Things You'll Need

Protective eyewear
Electrical pliers
Soldering iron
Secondary cell (rechargeable) battery
Photovoltaic (solar) cell (equal voltage to the battery)
1N4001 diode
Electrical wire
Electronic (rosin core) solder


Instructions
Put on the protective eyewear. Cut three pieces of wire, and strip each wire of 1/2 inch of insulation at each end. Using the electrical pliers, attach one end of the first wire to the negative terminal on the battery. Attach the other end of the first wire to the negative terminal on the solar cell assembly.

Connect one end of the second wire to the positive battery terminal. Connect the other end of this wire to the cathode lead (which is marked with a line) on the diode, and solder this connection.

Connect one end of the third wire to the anode lead on the diode. Solder this connection. Connect the other end of the third wire to the positive terminal on the solar cell assembly.