How To Build An Ac To Dc Adapter-ca1871

.puters-and-Technology Solder the AC wires to the primary winding of the transformer. Your transformer only needs to be big enough to supply the current that you need. Your DC voltage is determined by the ratio between the number of turns of the primary winding and the number of turns of the secondary winding. The amount of current that can be drawn is determined by the total number of windings on the transformer, and the size of the wire that is used for the winding. It’s a good idea to cover your connections with heat shrink tubing or hot glue. Solder your bridge rectifier to the leads on the secondary winding of the transformer. The rectifier needs to be rated for the current and amperage that you intend to be running through it. The rectifier has four terminals, usually marked. Solder both wires to the AC terminals of the rectifier. You’ll probably want to use a small circuit board for the connections. Cover your connections in heat shrink tubing or hot glue. Affix your wire ends to the project box, close it up and you’re ready to go. This is about as simple an adapter as you can make. Just to give you an idea, more .plex adapters can be made with inductors to smooth out power spikes, fuses, and power indicating LEDs. Cut your extension cord in half. On the male half separate the the two wire ends by 1 1/2 inches. Strip each wire 1/2 inch back. Take your DC power plug and do the same. Separate the wires and strip them. The stripped ends of both wire pairs go inside the electronics project box along with enough of each wire to .plete your project. Your box needs to be big enough to hold your transformer, rectifier, and a little wire. Connect two diodes to the output of a transformer that has a "center tap" such that both the positive and negative part of the AC cycle are converted. Often, a step-down transformer is used to change the 120 volts from the wall outlet down to a voltage needed by the device. Transformers and diode .binations are used in "wall warts" or power adaptors, many of which are probably around your home for cell phone chargers and phone answer machines. In a two-diode configuration, connect the anode end of a diode on one leg of the transformer and also connect the anode end of a second diode to the other transformer leg. The transformer must have a "center tap" connection. This will be the "ground" or negative connection. Connect the cathode end of both diodes together. This will be the positive DC output connection. Place an electrolytic capacitor across the DC output of the rectifier circuit –using either the two-diode or four-diode configuration–to further smooth out the DC voltage created by the full wave rectifier. Observe the polarity of the capacitor, connecting the positive end to the positive output of the rectifier circuit, and the negative end to the ground, or minus, connection–which is the transformer’s center tap in the case of a bridge rectifier. The voltage rating on the capacitor must be higher than the DC output voltage–with no "load" connected. Formulas have been devised to calculate the best capacitance value, but generally, a large capacitor value will reduce ripple significantly. Start by experimenting with a value of 100 microfarads for a circuit with a 12 volt output. An oscilloscope can be used to see the effect of a capacitor on ripple smoothing. About the Author: 相关的主题文章:

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