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How to build a 5V DC power supply |
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Steps
Consider one wire from the AC adapter the positive terminal. Consider the other wire ground. At this point it does not matter which one you choose to be positive or ground, but remember which is which from now on.
Connect the positive wire from the AC adapter to the side of the diode without the stripe marking on it.
Locate the lead on the side of the capacitor that has a stripe. Usually this stripe is white. This is the negative side, which you should connect to the ground terminal of the AC adapter. Connect the remaining terminal of the capacitor to the terminal of the diode with the stripe.
Connect Pin 1 of the voltage regulator IC to the node where the positive side of the capacitor and striped side of the diode connect. Pin 2 is the ground reference, also called the "common", and should be connected to the ground wire of the AC adapter. Pin 3 is the output. There will be 5 volts held between Pin 3 and ground.
Tips
Build the circuit on a prototyping board for easier construction
Try to use a 12V or lower AC adapter. Higher voltages will cause the 5V regulator to have to dissipate more power, causing it to get very hot and possibly too hot.
Your new voltage regulator will give up to 1.5 amperes of current at 5V. The 5V regulator IC will get hot as you draw more current out of it, so you might want to add a heat sink to it for higher power applications.
This is a very simplified design, and there are some improvements that you might find in the data sheet for the TL780-05.
To improve this design, add a full wave bridge rectifier instead of the half wave rectifier in the current design.
Add a capacitor from the 5V output to ground to give better transient response.
The TL780-05 5V regulator is capable of delivering 1.5A of current, but if the AC adapter you choose is not then the current output of your power supply will be limited to the current capability of the AC adapter.
You can find all the parts you need from electronics distributors such as Digikey and Mouser |
